Chemistry with Lab c832
What is the chemical formula of ammonium phosphate?
(NH 4) 3PO 4
Balance this equation: (NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + H2O(g)
(NH4)2Cr2O7(s) → Cr2O3(s) + N2(g) + 4H2O(g)
Neon Core
(Ne) is 1s2 2s2 2p6
bond distance
(also, bond length) distance between the nuclei of two bonded atoms
polar molecule
(also, dipole) molecule with an overall dipole moment
What are the legitimate values for the spin quantum number (ms)?
+1/2 and -1/2
What are the values for (ml) for a p orbital?
-1, 0, 1
What are the values for (ml) for a d orbital?
-2, -1, 0, 1, 2
Which of the following is a suffix used when naming cations?
-ium
What is the maximum number of electrons in a 3d set of orbitals?
10. A d energy sublevel (regardless of whether it is 3d or any other d energy sublevel) contains five orbitals. Each orbital contains two electrons, so the maximum number of electrons contained in a 3d energy sublevel is ten.
What is the molecular or formula mass of P4?
123.896 amu. P4 contains 4 phosphorus atoms. Phosphorus has an atomic mass of 30.974 amu. 4(30.974 amu) is 123.896 amu.
What is the molar mass of ammonia (NH3)?
17.031 g/mol
Identify the subshell in which electrons with the following quantum numbers are found: n=4, l=2?
4d. The quantum number n=4 means that the electron is in the fourth energy level. The quantum number l=2 means that the electron is in the D orbital
Bond order is a term that describes the number of electron pair bonds that are located between atoms in a molecule. Which of the following statements about bond order is not true?
A molecule made of two different atoms will always have a bond order of one.
Synthesis/Combination
A+B-->AB * Example: hydrogen and oxygen combine and make water- 2H₂+O₂-->2H₂O * 2 molecules of hydrogen are needed to react with 1 molecule of oxygen to form 2 molecules of water.
Single Replacement
AB+C-->A+BC A+BC-->B+AC * Only one element is trading partners
Which option best describes HNO3(aq), HClO4(aq), and H3PO4(aq)?
Acids. Acids are substances that will easily separate into one or more hydrogen ions (H+) and an anion when in a water solution. The formulas given are for nitric acid, perchloric acid, and phosphoric acid.
What does it mean to say an equation is balanced?
An equation is balanced when the same number of each element is represented on the reactant and product sides. Having the same number of each element represented on the reactant and product sides of the equation satisfies the law of conservation of matter.
monoatomic ion
An ion that consists of only one atom
Which group of elements is listed in decreasing order of atomic radius?
B, C, N, O
Write the formula for barium nitrate.
Ba(NO3)2. Barium nitrate is formed from the barium ion, Ba2+, and the nitrate ion, NO3-. The charges do not cancel, so two nitrate ions are needed to cancel out the charge on barium. The chemical formula for barium nitrate is Ba(NO3)2.
Write the formula for carbon tetrachloride.
CCl4
Balance the following chemical equation: CH4 + O2 → CO2 + H2O
CH4 + 2O2 → CO2 + 2H2O
Which of the following molecules has polar bonds but is considered a nonpolar molecule?
CO2. The C-O bond would be considered polar, but since there are no net changes in the dipole moment due to the molecular symmetry, this molecule is nonpolar.
What type of reaction is 2H₂O₂-->2H₂0+O₂?
Decomposition
Which element has the ground state electron configuration 1s2 2s2 2p6 3s2 3p6 4s2?
Calcium
Which statement is true for either of the carbon atoms in the molecule?
Carbon has three electron domains. The predicted geometry around is trigonal planar. The bond angles are exactly 120° because there is no contribution from lone electron pairs.
Which of the following is the best definition of bond order?
Bond order is the number of electron pair bonds between two atoms. Bond order is a numerical description of the number of bonds between two bonded atoms. It varies between numerical values of one and three.
Balance this equation: H2(g) + I2(s) → HI(s)
H2(g) + I2(s) → 2HI(s)
Write the formula for dihydrogen monoxide.
H2O
Which equation describes a physical change?
H2O(s) → H2O(l). Water is changing state of matter from a solid to a liquid.
Which of the following statements best states the Pauli Exclusion principle?
Each electron in an atom must have a unique set of quantum numbers describing it.
What is electron affinity?
Electron affinity is defined as the energy change when an electron is added to a neutral atom in a gaseous sample; X + e− → X − + EA; when EA < 0, energy is released.
How is electron-pair geometry different from molecular structure?
Electron-pair geometry considers the placement of all electrons.
Why is it important for an equation to be balanced?
Equations must be balanced to accurately reflect the law of conservation of matter.
Write the formula for hydrochloric acid.
HCl
What is the chemical formula for hypochlorous acid?
HClO
Write the formula for hydrofluoric acid.
HF
What is the net ionic equation for the reaction that occurs when potassium hydroxide and iron(III) nitrate solutions are mixed?
Fe 3+(aq) + 3OH -(aq) → Fe(OH) 3(s)
Write the formula for iron(III) oxide.
Fe2O3
Which is the more polar bond?
HF. There is a greater electronegativity difference between hydrogen and fluorine than between hydrogen and chlorine because fluorine is more electronegative than chlorine.
Which compound has the highest viscosity?
HOCH 2CH 2OH
The concept of electronegativity was developed by which one of the following scientists?
Linus Pauling developed the concept of electronegativity to describe the desire of an atom to take on (or to give up) additional electron density.
Based on their positions in the periodic table, predict which of the following atoms has the largest first ionization energy: Mg, Ba, B, O, Te. response - correct
O, because it is the smallest atom. The smallest atom has the largest first ionization energy because the electrons are held more tightly by the nucleus, which makes the electrons harder to remove
Which is the more polar bond?
OH. There is a greater electronegativity difference between hydrogen and oxygen than between hydrogen and sulfur because oxygen is more electronegative than sulfur.
Write the formula for sulfur trioxide
SO3
Aqueous hydrogen fluoride (hydrofluoric acid) is used to etch glass and to analyze minerals for their silicon content. Hydrogen fluoride will also react with sand (silicon dioxide). Write an equation for the reaction of solid silicon dioxide with hydrofluoric acid to yield gaseous silicon tetrafluoride and liquid water.
SiO2(s) + 4HF(aq)→SiF4(g)+2H2O(l)
Write the formula for tin(IV) oxide.
SnO2
What does the quantum mechanical model show us?
The probability of finding the electron in a region of space.
For a given element, how does the size of the anion compare to the size of the atom?
The anion is larger. An atom becomes an anion by gaining one or more electrons. When an atom gains an electron, it becomes larger because the attractive forces from the nucleus are distributed among more electrons. The result is that the ion expands.
Which of the following choices correctly summarizes the relationship between the bond distance and the bond order for any pair of bonded atoms?
The bond distance decreases as you increase the bond order.
How does the size of the cation compare to its corresponding atom?
The cation is smaller. Cations are formed when an atom loses one or more electrons and takes on a positive charge. Losing an electron causes the nucleus to pull harder on the remaining electrons. This causes a decrease in size. Therefore, the cation is smaller than its corresponding atom.
Which group has the highest electron affinity?
The halogens have the highest electron affinity. The halogens need to accept one electron to completely fill their outer orbital.
Balance this equation: TiCl4(s) + H2O(g) → TiO2(s) + HCl(g)
TiCl4(s) + 2H2O(g) → TiO2(s) + 4HCl(g)
Which set of quantum numbers is possible for the 2 electrons of helium?
(1, 0, 0, +1/2) and (1, 0, 0, -1/2) Both electrons are in the 1s orbital (as indicated by the first 3 numbers), but one has spin up (+1/2) and the other has spin down (-1/2)
Which electron configuration correctly represents an ion of strontium with a +2 charge?
1s 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Which electron configuration correctly represents an atom of nitrogen?
1s2 2s2 2p3
Balance this equation: Al(s) + H2SO4(aq) → Al2(SO4)3(s) + H2(g)
2Al(s) + 3H2SO4(aq) → Al2(SO4)3(s) + 3H2(g)
Balance this equation: Pb(s) + H2O(l) + O2(g) → Pb(OH)2(s)
2Pb(s) + 2H2O(l) + O2(g) → 2Pb(OH)2(s)
d orbital shape
4 leaf clover. l=2
What is the maximum number of electrons that may be found in a 3p energy sublevel?
6. The 3p energy sublevel has three orbitals with at most 2 electrons in each orbital, so it can contain a maximum of 6 electrons.
Identify the subshell in which electrons with the following quantum numbers are found: n=6, l=0?
6s. The quantum number n=6 means that the electron is in the sixth energy level. The quantum number l=0 means that the electron is in the S orbital.
Double Replacement
AB+CD-->AC+BD *Two elements trade partners. * No mass is lost.
Write the formula for aluminum carbide.
Al4C3
Which of the following statements is false?
An atom with a low electronegativity and a formal charge of 0 will have a tendency to acquire another electron.This statement is false because an atom with a low electronegativity will have a tendency to avoid acquisition of another electron, no matter what its formal charge is.
Which statement is not a possible explanation for behavior that violates the octet rule?
Atoms will always try to maximize their formal charge.This is false. Atoms never want to maximize their formal charges. Their nature is actually to assume a charge that is as close to 0 as possible.
Which equation identifies the reactants and products of a combustion reaction?
CH3OH(g) + O2(g) → CO2(g) + H2O(g)
Which configuration represents the ground state electron configuration of a neutral calcium atom?
Ca: 1s2 2s2 2p6 3s2 3p64s2
Which molecule matches the main intermolecular force present in the molecule?
Cl 2; London forces
Write the formula for chlorine trifluoride.
ClF3
Which of the following statements is correct according to Hund's rule?
Electrons will occupy separate degenerate orbitals and maintain parallel spins before pairing up.
Why does chlorine have a higher electron affinity than fluorine?
Fluorine is a much more compact atom than chlorine. Because fluorine is so small, the electrons are packed into a tiny volume and the repulsive forces between electrons cause it to be less stable than in chlorine, which has more room for the electrons to share.
What is the phase change when matter changes from a liquid to a solid?
Freezing
What is the net ionic equation in the following reaction? 2 KOH(aq) + H 2SO 4(aq) → K 2SO 4(aq) + 2 H 2O(l)
H +(aq) + OH -(aq) → H 2O(l)
Write the formula for sulfuric acid.
H2SO4
What is the chemical formula for hydrofluoric acid?
HF
Which of the following statements does not correctly describe the ICl4− anion?
ICl4− has a square planar electronic geometry. This statement is not true. The molecular geometry of the ion is square planar. The electronic geometry is octahedral.
Which of the following statements is not correct?
If a molecule has an electronegativity difference value of 1.6, you can assume that the atom that has the lesser electronegativity value has a greater share of the electrons in the bond. The atom with the higher electronegativity will control a greater share of the electrons in the bond, so this statement is not true.
Scientists use electronegativity values of elements to predict how elements will react. Which of the following statements is not true about an atom of an element as a component of a molecule having resonance structures?
If the element is highly electronegative, the atom will likely have a formal charge of +1 in a stable resonance structure. his is not true for an element whose atom is a component of a stable form of the molecule. If a stable molecule is composed of highly electronegative elements, the formal charges of the atoms will be either 0 or −1.
How can a molecule that contains polar bonds be nonpolar?
If the polar bonds cancel each other out, then the molecule is nonpolar. As long as the polar bonds are compensated (for example, if two identical atoms were found directly across the central atom from one another), the molecule can be nonpolar.
The bond energy of carbon-nitrogen single bond is 305 kJ per mole. C-N + 305 kJ → C · + · N Which of the following statements is not true?
If the two atoms had a triple bond, the theoretical bond energy would be about 1,200 kJ. Theory predicts that you would need about 3 × 305 kJ, or about 900 kJ to break a triple bond.
Which type of bond forms between two ions with opposite charges?
Ionic bond. This type of bond forms between two ions with opposite charges.
Which of the following statements provides the best explanation for why it is harder to remove an electron from an atom of neon than from an atom of fluorine?
It is harder to remove an electron from neon than fluorine because of increased nuclear charge (Z = 10).
What are the spectator ions in the following unbalanced double replacement precipitation reaction? Pb(NO 3) 2(aq) + KI(aq) → KNO 3 (aq) + PbI 2 (s)
K +, NO 3 -
What information does Schrodinger's equation combine?
Kinetic energy, potential energy, and wave properties.
What are the spectator ions in solution when iron(II) bromide and lithium carbonate are mixed?
Li +(aq) and Br -(aq)
Which type of intermolecular force is present in solid CO 2?
London forces
What are all of the intermolecular forces exhibited by a pure sample of CH 2Cl 2?
London forces and dipole-dipole forces
Write the formula for ammonium chloride.
NH4Cl
A solution of silver nitrate (AgNO3 ) is added to a solution of sodium hydroxide (NaOH). In the precipitation reaction that occurs, which ions will be spectator ions?
Na+ and NO3-. Ag++ NO3-+ Na++ OH - Next, decide which (if any) compound will precipitate from these ions. Most hydroxides (including silver hydroxide) are insoluble. (Hydroxides of alkali metals such as NaOH are an exception to this rule.) Therefore, the silver and hydroxide ions will precipitate out of the solution as silver hydroxide (AgOH(s)). The two ions that do not participate in this reaction are Na+ and NO3-. These are the spectator ions.
Which group of elements is listed in increasing order of first ionization energy?
Na, S, Cl, Ar
Write the formula for sodium sulfide
Na2S
Write the formula for sodium bicarbonate.
NaHCO3
What is the name of the compound HNO 3?
Nitric acid
What is the name of the compound NO 2?
Nitrogen dioxide
Which type of bond forms between atoms of identical electronegativities?
Nonpolar covalent bond. This type of bond is sometimes referred to as a pure covalent bond.
Which set of elements is correctly ordered from smallest atomic radius to largest atomic radius?
O, N, C, B
Given their positions within the periodic table, which atom is more electronegative? (O or N)
O. O is further to the right on the periodic table than N.
How does the octet rule explain the common ion of oxygen?
Oxygen must gain 2 electrons to become stable. Oxygen has six electrons in its outer shell. To fill its outer shell and become stable, it must gain two electrons rather than lose two electrons. The ion of oxygen has 8 electrons in its outer shell and therefore has a 2− charge.
Which of the following correctly ranks the atoms in order of increasing radius?
P < Si < Ge < Ga. Atomic radius decreases from left to right across the periodic table as the effective nuclear charge increases, and it increases from top to bottom as electron shielding increases.
Given their positions within the periodic table, which atom is more electronegative? (P or Ba)
P. P is further to the right on the periodic table than Ba.
Balance this equation: P4(s) + O2(g) → P4O10(s)
P4(s) + 5O2(g) → P4O10(s)
Balance this equation: P4(s) + Cl2(g) → PCl3(l)
P4(s) + 6Cl2(g) → 4PCl3(l)
What is the chemical formula for tetraphosphorus decoxide?
P4O10
Which of the following molecules is polar?
PCl3. This molecule has a lone pair on the central phosphorus atom which makes the entire molecule asymmetrical and polar.
Balance this equation: PCl5(s)+ H2O(l) → POCl3(l) + HCl(aq)
PCl5(s) + H2O(l) → POCl3(l) + 2HCl(aq)
An ionic compound that contains lead is soluble in water. Of the four compounds listed, which should be the most soluble?
Pb(ClO3 )2. Because chlorates are soluble in water, lead chlorate (Pb(ClO3 )2 ) is a soluble ionic compound. Therefore, the unknown lead-containing compound is more likely to be lead chlorate than any of the other answer choices. (Note that you don't know for sure what the unknown compound is. However, you are able to rule out several possibilities based on the fact that the compound is soluble.)
Which type of bond forms between atoms of different electronegativities?
Polar covalent bonds are covalent bonds with a positive end and a negative end.
atomic orbital shapes
S-Orbital: all spherical. probability of finding an electron depends on distance from the nucleus not direction, ml = 0, only 1s orbital per shell P-Orbital: dumbbell shaped, three orbitals: 2px, 2py, 2pz D-Orbital: five orbitals, more complex than s and p orbitals F-Orbitals: seven D-Orbitals, complex shapes.
Balance this equation: Sc2O3(s) + SO3(l) → Sc2(SO4)3(s)
Sc2O3(s) + 3SO3(l) → Sc2(SO4)3(s)
Based on their positions in the periodic table, arrange the ions in order of increasing radius.
Si4+ Al3+ Ca2+ K+
What type of reaction is Mg+2HCl-->MgCl₂+H₂?
Single Replacement
What is the electron configuration of sodium ion (Na+ )?
Sodium ion has one less electron than neutral sodium. Therefore, it has the same electron configuration as neon.
Which of the following statements is not true about bond energy?
The average bond energy of a carbon-chlorine molecule is the energy you have to remove in order to break one mol of C-Cl bond. This statement is false. It would be true if you replaced the word remove with input or introduce.
How do electrons react to other electrons?
They are repelled by each other. Electrons have negative charges. Like charges repel each other.
What is the chemical formula for zinc(II) hydroxide?
Zn(OH) 2
What is the ground state electron configuration of scandium?
[Ar] 4s2 3d1
weak acid
acid that reacts only to a slight extent when dissolved in water to yield hydronium ions
Write the name for Al2(CO3)3.
aluminum carbonate
NH₄⁺
ammonium
Write the name for (NH4)2Cr2O7.
ammonium dichromate
Which option best describes fluoride anion (F- )?
an anion
polyatomic ion
an ion made of two or more ions chemically bonded together.
molecular equation
chemical equation in which all reactants and products are represented as neutral substances
Oxyacids are:
compounds that contain hydrogen, oxygen, and at least one other element, and are bonded in such a way as to impart acidic properties to the compound. Oxyacids contain hydrogen, oxygen, and at least one other element.
double bond
covalent bond in which two pairs of electrons are shared between two atoms
Write the name for N2O5.
dinitrogen pentoxide
bond length
distance between the nuclei of two bonded atoms at which the lowest potential energy is achieved
core electron
electron in an atom that occupies the orbitals of the inner shells.
electron configuration
electronic structure of an atom in its ground state given as a listing of the orbitals occupied by the electrons.
valence electrons
electrons in the outermost or valence shell (highest value of n) of a ground-state atom that determine how an element reacts.
Which of the following elements is the least electronegative and the most electronegative, respectively?
francium, fluorine. Francium, being a large atom with a great deal of electron shielding, has the lowest electronegativity. Fluorine, being a small atom with little shielding, has the highest electronegativity.
Write the name for GaN.
gallium(III) nitride
HPO₄²⁻
hydrogen phosphate
HSO₃⁻
hydrogen sulfite (bisulfite)
Which elements in the following chemical equation are not balanced? 2AgNO3 + H2S → Ag2S + HNO3
hydrogen, nitrogen, and oxygen
Write the name for IF7.
iodine heptafluoride
spectator ion
ion that does not undergo a chemical or physical change during a reaction, but is required to maintain charge neutrality
Write the name for PbO2.
lead(IV) oxide
axial position
location in a trigonal bipyramidal geometry in which there is another atom at a 180° angle and the equatorial positions are at a 90° angle
subshell
mathematical description of an atomic orbital that describes the shape of the orbital; it can be used to calculate the probability of finding the electron at any given location in the orbital, as well as dynamical variables such as the energy and the angular momentum.
Pauli Exclusion Principle
no two electrons in the same atom can have the same set of four quantum numbers.
of relatively high solubility; dissolving to a relatively large extent soluble
of relatively high solubility; dissolving to a relatively large extent
insoluble
of relatively low solubility; dissolving only to a slight extent
equatorial position
one of the three positions in a trigonal bipyramidal geometry with 120° angles between them; the axial positions are located at a 90° angle
covalent radius
one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond
degenerate orbitals
orbitals that have the same energy
What are the names for the 3 quantum numbers in the Schrodinger's equation?
principal, angular, magnetic
Aufbau principle
procedure in which the electron configuration of the elements is determined by "building" them in order of atomic numbers, adding one proton to the nucleus and one electron to the proper subshell at a time.
shell
set of orbitals with the same principal quantum number, n.
linear
shape in which two outside groups are placed on opposite sides of a central atom
Hund's Rule
states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals.
SO₄²⁻
sulfate
electron spin quantum number (ms)
the fourth quantum number of an electron having a value of +1/2 or -1/2 corresponding to up and down electron spin.
Write the name for XeF6
xenon hexafluoride
What are the permissible values for the quantum number (l) when n= 2?
0, 1
What are the permissible values for the angular quantum number (l) when n=3?
0, 1, 2
What are the permissible values for the angular quantum number (l) when n=4?
0, 1, 2, 3
What is the total mass (amu) of carbon in the following molecule? CH4
12.01 amu. CH4 contains 1 carbon atom. Carbon has an atomic mass of 12.01 amu. 1(12.01 amu) = 12.01 amu.
What is the molecular or formula mass of Ca(NO3)2?
164.10 amu. Ca(NO3)2 contains 1 calcium atom with a mass of 40.08 amu, 2 nitrogen atoms with a mass of 14.01 amu, and 6 oxygen atoms with a mass of 16.00 amu. 1(40.08 amu) + 2(14.01 amu) + 6(16.00 amu) = 164.10 amu
What is the maximum number of electrons that can occupy the 3rd electron shell?
18. The 3rd electron shell has 3 subshells: 3s, 3p, and 3d. The 3s subshell can fit 2 electrons, the 3p subshell can fit 6 electrons, and the 3d subshell can fit 10 electrons.
Identify the subshell in which electrons with the following quantum numbers are found: n=1, l=0?
1s. The quantum number n=1 means that the electron is in the first energy level. The quantum number l=0 means that the electron is in the S orbital. 0 mb
What is the ground state electron configuration for boron?
1s2 2s2 2p1
What is the ground state electron configuration for oxygen?
1s2 2s2 2p4
What is the electron configuration of the oxide ion (O2- )?
1s2 2s2 2p6
What is the electronic configuration for Ag?
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d10
Which electron configuration correctly represents an atom of nickel?
1s2 2s2 2p6 3s2 3p6 4s2 3d8
What is the electronic configuration of the S 2- ion?
1s2 2s2v2p6 3s2 3p6
How many angular modes do the d orbitals have?
2
In the following balanced chemical equation, 2Al(OH)3 + 3H2SO4 → Al2(SO4 )3 + 6H2O what is the ratio of water molecules produced per sulfuric acid in the reaction?
2 molecules of water per molecule of sulfuric acid. The balanced equation is: 2Al(OH)3 + 3H2SO4 → Al2 (SO4 )3 + 6H2O For every 3 molecules of sulfuric acid in the balanced equation, 6 molecules of water are produced. By reducing the coefficients, this gives a ratio of 2 molecules of water per molecule of sulfuric acid.
In a balanced chemical reaction, 2 molecules of ethane (C2H6 ) react with 7 oxygen molecules (O2 ) to produce carbon dioxide (CO2 ) and water (H2O) molecules. Complete the balancing of this equation.
2C2H6 + 7O2 → 4CO2 + 6H2O. Ethane and oxygen are on the left side of the equation, carbon dioxide and water are on the right side. You know that there are 2 molecules of ethane and 7 molecules of oxygen. There are 4 carbon atoms on the left side, so place a 4 in front of the carbon dioxide to balance the carbon atoms. There are 12 hydrogen atoms on the left side. To balance hydrogen, place a 6 in front of the water. This also balances the oxygen atoms on both sides.
In the chemical equation 2Mg + O2 → MgO, how must the product be written in order for the equation to be balanced?
2MgO
Balance this equation: Na(s) + H2O(l) → NaOH(aq) + H2(g)
2Na(s) + 2H2O(l) →2NaOH(aq) + H2(g)
Balance the following chemical equation: Na3 PO4 + CaCl2 → Ca3(PO4 )2 + NaCl
2Na3 PO4 + 3CaCl2 → Ca3 (PO4 )2 + 6NaCl
Write a balanced molecular equation describing the following chemical reaction: When solid sodium chloride is added to aqueous sulfuric acid, hydrogen chloride gas and aqueous sodium sulfate are produced.
2NaCl (s) + H2SO4 (aq) → 2HCl (g) + Na2SO4 (aq). Sodium chloride comes from the sodium ion, Na+, and the chloride ion, Cl-. The charges cancel so the chemical formula is NaCl. Since the description says it is a solid, it gets a (s) next to it. Sulfuric acid comes from the hydrogen ion, H+, and the sulfate ion, SO42-. Since the charges do not cancel, two hydrogen ions are required to balance out the charge on the sulfate ion. The chemical formula for sulfuric acid is H2SO4. Since the description says it is aqueous, it gets a (aq) next to it. The words "are produced" indicate a move to the product side. Hydrogen chloride comes from the hydrogen ion, H+, and the chloride ion, Cl-. The charges cancel out so the chemical formula is HCl. Since the description says it is a gas, it gets a (g) next to it. Sodium sulfate comes from the sodium ion, Na+, and the sulfate ion, SO42-. Since the charges do not cancel, two sodium ions are required to balance out the charge on the sulfate ion. The chemical formula for sulfuric acid is Na2SO4. Since the description says it is aqueous, it gets a (aq) next to it. The coefficients in the balanced equation ensure that the law of conservation of matter is satisfied. Each side of the equation contains the same amount of each element.
Which equation is correctly balanced for the following reaction? sodium hydroxide → sodium oxide + water
2NaOH → Na2O + H2O. Sodium hydroxide is written as NaOH. Sodium oxide is written as Na2O and water is H2O. By placing a coefficient of 2 in front of the sodium hydroxide, the equation becomes balanced.
Identify the subshell in which electrons with the following quantum numbers are found: n=2, l=1?
2p. The quantum number n=2 means that the electron is in the 2nd energy level. The quantum number l=1 means that the electron is I. the P orbital.
Balance this equation: Fe(s) + H2O(l) → Fe3O4(s) + H2(g)
3Fe(s) + 4H2O(l) → Fe3O4(s) + 4H2(g)
Identify the subshell in which electrons with the following quantum numbers are found: n=3, l=2?
3d. The quantum number n=2 means that the electron is in the third energy level. The quantum number l=2 means that the electron is in the D orbital
Balance this equation: Fe(s) + O2(g) → Fe2O3(s)
4Fe(s) +3O2(g) → 2Fe2O3(s)
Write separate equations for the reactions of the solid metals magnesium, aluminum, and iron with diatomic oxygen gas to yield the corresponding metal oxides. (Assume the iron oxide contains Fe3+ ions.) For this question, write the equation for the reaction of solid iron with diatomic oxygen gas.
4Fe(s)+3O2(g)→2Fe2O3(s)
Which sublevel is filled after the 5s sublevel?
4d. The order in which sublevels are filled can be determined by following the arrangement of elements on the periodic table. The 5s region (Rb and Sr) is followed by the 4d region (Y to Cd), moving left to right across the periodic table. The diagonal rule can also be used to determine the order for filling sublevels.
Decomposition
AB-->A+B * More than one molecule of water is needed to start the reaction. * Example: When water decomposes, it makes hydrogen and oxygen gas- 2H₂O-->2H₂+O₂ * 2 water molecules produce 2 molecules of hydrogen gas and 1 molecule of oxygen gas.
Which chemical properties do groups on the periodic table share?
All members of the group have similar electron configurations. Each member of a group has a similar electron configuration in their outer orbitals, but they have differing numbers of total electrons. Because the outer electrons are the ones that give an atom its chemical properties, all members of a group show similar chemical properties.
Which of the following ideas is not a basis for the concept of electronegativity?
Atomic radius. The atomic radius is not a basis for the concept of electronegativity. Electronegativity is a combination of measured quantities: ionization energy, electron affinity, and bond length.
Why is it important to understand where the electrons are?
Atoms bond through the interaction of electrons. Knowing where the electrons are in an atom allows prediction of how atoms will bond by understanding which electrons are available.
Which of the following molecules would be considered polar?
CH3F. This molecule has a change in dipole moment due to the one fluorine atom, which makes the entire molecule asymmetrical and polar.
Combustion
CH₄+2O₂--> CO₂+2H₂O+Energy * Compounds of hydrogen and carbon react with oxygen to form carbon dioxide and water.
Which is the more polar bond?
CN. There is a greater electronegativity difference between carbon and nitrogen. There is no electronegativity difference between nitrogen and nitrogen, making that bond nonpolar.
Which is the more polar bond?
CO. There is a greater electronegativity difference between carbon and oxygen than between nitrogen and oxygen because carbon is less electronegative than nitrogen.
Which of the following correctly ranks the atoms and ions in order of increasing size?
Ca2+, K+, Ar, Cl-. Notice that all four ions and atoms listed would have the same number of electrons and the same electron configuration as Ar—the term for this is "isoelectronic." What they differ by is their number of protons. The greater the number of protons, the greater the nuclear charge and the more tightly those 18 electrons are pulled in toward the nucleus, resulting in a smaller atomic or ionic radius.
Balance this equation: Ca3(PO4)2(aq) + H3PO4(aq) → Ca(H2PO4)2(aq)
Ca3(PO4)2(aq) + 4H3PO4(aq) → 3Ca(H2PO4)2(aq)
Write the formula for calcium phosphide.
Ca3P2
Which of the following is the correct name for CdSO3?
Cadmium (II) sulfite. Since SO3 is sulfite, which has a charge of 2-, then the charge for cadmium is 2+ in order to create a neutral molecule. We write the charge for cadmium in parentheses as Roman numerals because cadmium can carry different charges.
Which of the following elements most strongly attracts an added electron to a neutral atom?
Chlorine. Chlorine is relatively small, and also only needs one more electron to have a full valence shell. Therefore, one additional electron makes it much more stable.
Based on their positions in the periodic table, predict which of the following atoms has the smallest atomic radius: Mg, Sr, Si, Cl, I.
Cl, because it has less shielding than Sr and I and because it has more protons in the nucleus than Si and Mg. Cl has less shielding than Sr and I, which means its electrons are located closer to the nucleus. Cl has more protons in the nucleus than Si and Mg, which means that the electrons are held more tightly by the nucleus.
Given their positions within the periodic table, which atom is more electronegative? (Cl or Br)
Cl. Cl is closer to the top of the periodic table than Br.
What kind of reaction is this? C₁₀H₈ + 12O₂ --> 10CO₂ + 4H₂O
Combustion Reaction
What is the phase change when matter changes from a gas to a liquid?
Condensation
What is the name for the compound Cu(OH)2?
Copper(II) hydroxide is the correct name for the compound. The hydroxide has a 1- charge. Since the compound contains 2 hydroxide ions, then the charge on copper must be 2+.
Which element has the lowest ionization energy? Al, Cs, Mg, Na
Cs
Write the formula for cesium fluoride.
CsF
What is the chemical formula for copper(I) sulfate?
Cu 2SO 4
Write the formula for copper(II) sulfate.
CuSO4
Which of the following statements is not true? response - correct
Each C-O bond in the carbonate anion has a bond energy that is less than the bond energy value for a C-O double bond and greater than the bond energy value for a C-O triple bond. This statement is incorrect. A triple bond has more energy than a double bond because it has one more bond. In this situation, the actual bond order is somewhere between one and two, not two and three. The observed bond energy for any bond would be somewhere between the bond energies for a single bond and a double bond of carbon and oxygen.
What is electronegativity?
Electronegativity is a quantitative measure of the tendency of an atom to attract electrons to itself. This is the correct definition for electronegativity. An atom that has a higher electronegativity will exert a greater pull on electrons from another element in the formation of a bond
Which of the following periodic trends cannot be directly measured?
Electronegativity. Electronegativity is a combination of measured quantities: ionization energy, electron affinity, and bond length.
Hund's rule
Every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.
What is the correct formula for iron (III) cyanide?
Fe(CN)3. Iron has a symbol of Fe with a charge of 3+, as identified by the roman numerals. Cyanide has the symbol CN with 1- as the charge. We need three cyanide ions to balance the charge of the iron, and since we want the whole symbol to get multiplied by three, the three gets written outside the parentheses in the symbol.
Which of the following represents a balanced chemical equation for the word equation below? iron(II) sulfide + hydrochloric acid → iron(II) chloride + hydrogen sulfide
FeS + 2HCl → FeCl2 + H2S. FeS is the correct formula for iron(II) sulfide; FeCl2 is the correct formula for iron(II) chloride; HCl correctly describes hydrochloric acid and H2S is the correct formula for hydrogen sulfide. By placing a coefficient of 2 in front of the hydrochloric acid, the equation becomes balanced for all atoms.
Why does SiH 4 have a higher boiling point than CH 4?
London forces between SiH 4 molecules are stronger than those between CH 4 molecules.
Write the formula for potassium chlorate.
Potassium chlorate is formed from the potassium ion, K+, and the chlorate ion, ClO3-. The charges cancel so the chemical formula for potassium chlorate is KClO3.
Balance this equation: PtCl4(s) → Pt(s) + Cl2(g)
PtCl4(s) → Pt(s) + 2Cl2(g)
Based on their positions in the periodic table, rank the following atoms in order of increasing first ionization energy:
Rb Li N F
Which group of elements is listed in order of increasing electron affinity?
Rb, K, Na, Li
Which of the following compounds would you expect to be the most soluble?
Sodium sulfate. This compound is soluble. Sulfates are generally soluble.
What is the name of the compound Na 2S?
Sodium sulfide
What type of reaction is 2Mg+O₂-->2MgO
Synthesis
What is the difference between the 2p and a 3p orbital?
The 3p orbital is farther from the nucleus than the 2p orbital.
What happens to the size of an atom when it loses an electron?
The atom becomes smaller.The nucleus of an atom is positively charged and the electrons are negatively charged. If one charge is increased due to removal or addition of an electron, the size of the atom will change. When an atom loses an electron, the size of the ion decreases because the nucleus pulls more on the remaining electrons and compacts the atom.
Within a period, what happens to the size of an atom as the atomic mass increases?
The atom gets smaller. Within a period, as the nuclear charge increases, the size of the atom decreases. The increase in nuclear charge increases the atomic force the nucleus exerts on the electrons, which experience the same shielding because they are in the same valence shell. The increased atomic forces pull the electrons in and reduces the size of the atom.
Which statement best describes why we do not need the electronegativity values for carbon and oxygen to explain why the carbon dioxide molecule is nonpolar?
The dipole moments of the polar O-C bonds cancel out each other, so you do not need to compare electronegativity values. The electronegativity values do affect the bond dipole value and direction in each bond. But the net bond dipole moment is zero because the two dipole moments cancel out each other.
Why does electron affinity generally increase as you go from left to right across the periodic table?
The elements on the right side of periodic table usually have a larger number of protons and a smaller atomic radius than elements on the left side of the periodic table. The number of protons increases moving from left to right across the periodic table, and the atomic radii decrease. The ability to add an electron to a neutral atom depends on the number of protons causing the attraction compared to the volume of the electron cloud.
Which statement best explains why the molecule in the diagram is polar? O=C=S
The molecule is linear but is polar because the electronegativity of oxygen is greater than the electronegativity of sulfur. The molecule is linear, but it is polar. This is because the electronegativity of oxygen is greater than the electronegativity of sulfur.
Which of the following is true for the molecule CH2Cl2?
The molecule is polar. The C-H bonds are slightly polar and the C-Cl bonds are polar. The fact that the bonds are polar and the molecule is asymmetrical means that the molecule is polar.
Though neon is a relatively small atom with a relatively high nuclear charge, it is difficult to add an electron to a neon atom. Which of the following is the best explanation of this phenomenon?
The next electron added to neon would have to be placed in a higher energy level (the n = 3 level).
Why is the HOH molecule bent, whereas the HBeH molecule is linear?
There are two unshared pairs of electrons on the O in HOH, but there are no unshared pairs of electrons on the Be in HBeH. The placement of the two sets of unpaired electrons in water forces the bonds to assume a tetrahedral arrangement, and the resulting HOH molecule is bent. The HBeH molecule (in which Be has only two electrons to bond with the two electrons from the hydrogens) must have the electron pairs as far from one another as possible and is therefore linear.
The PClF4 is a trigonal bipyramidal molecule with chlorine in one of the axial sites. Which statement about the PClF4 molecule is not true?
There is no dipole moment because the trigonal plane atoms cancel each other's polarities and the two axial bonds cancel each other's polarities. This statement is not true. The vector for the P-Cl bond is much shorter than the vector for any P-F bond. The electronegativity of F is greater than the electronegativity of Cl. Because they are both "pulling" on the same P atom, there is a net dipole moment toward the axial fluorine atom.
There are 3 p orbitals that are aligned with their major axes along the x, y, and z axes. What is the origin of these 3 p orbitals?
They are the solutions for the 3 values of the magnetic quantum number.
What is the difference between a 2s orbital and a 2p orbital?
They have different angular momentum quantum numbers. All S orbitals have an angular momentum quantum number of 0, whereas all P orbitals have an angular momentum quantum number of 1.
What is the ground state electron configuration of aluminum?
[ Ne] 3s2 3p1
What is the electron configuration of a neutral copper atom?
[Ar] 4s1 3d10 Copper is a d-block exception. A totally filled d subshell is preferred, and n = (row # -1) for the d-block metals.
What is the ground state electron configuration of manganese?
[Ar] 4s2 3d5
What is the electron configuration for the Mo+ ion?
[Kr] 4d5 Mo is a d-block exception. A half-filled d subshell is preferred, and the one electron in the s subshell will be removed in the Mo+ ion.
combination reaction (also known as a synthesis reaction)
a reaction where two or more elements or compounds (reactants) combine to form a single compound (product)
atomic orbital
a region of space in which there is a high probability of finding an electron. mathematical function that describes the behavior of an electron in an atom, wave function.
acid
a substance that increases the concentration of hydrogen ions when dissolved in water.
base
a substance that increases the concentration of hydroxide ions when dissolved in water.
decomposition reaction
a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds
C₂H₃O₂⁻
acetate
Write the acid name for HC2H3O2.
acetic acid
Neutralization Reaction
acid + base --> salt + water (this is a type of double replacement reaction)
strong acid
acid that reacts completely when dissolved in water to yield hydronium ions
orbital
an allowed energy state of an electron in an atom or molecule. not the same as orbit.
anion
an ion with a negative charge
cation
an ion with a positive charge
electron affinity
energy required to add an electron to a gaseous atom to form an anion
ionization energy
energy required to remove an electron from a gaseous atom or ion. The associated number (e.g., second ionization energy) corresponds to the charge of the ion produced (X2+)
Electron Shielding
partial blocking of the nuclear charge by electrons close to the nucleus.
p orbital shape
peanut or dumbbell shaped region of space with high electron density, describes orbitals with l =1.
PO₄³⁻
phosphate
Electropositivity
possessing a lower than normal electron density; an electropositive atom easily gives up electron density in a bond.
Write the name for KC2H3O2.
potassium acetate
Write the name for KBr.
potassium bromide
neutralization reaction
reaction between an acid and a base to produce salt and water
acid-base reaction
reaction involving the transfer of a hydrogen ion between reactant species
precipitation reaction
reaction that produces one or more insoluble products; when reactants are ionic compounds, sometimes called double displacement or metathesis
single displacement ( replacement) reaction
redox reaction involving the oxidation of an elemental substance by an ionic species
trigonal bipyramidal
shape in which five outside groups are placed around a central atom such that three form a flat triangle with 120° angles between each pair and the central atom, and the other two form the apex of two pyramids, one above and one below the triangular plane
tetrahedral
shape in which four outside groups are placed around a central atom such that a three-dimensional shape is generated with four corners and 109.5° angles between each pair and the central atom
octahedral
shape in which six outside groups are placed around a central atom such that a three-dimensional shape is generated with four groups forming a square and the other two forming the apex of two pyramids, one above and one below the square plane
trigonal planar
shape in which three outside groups are placed in a flat triangle around a central atom with 120° angles between each pair and the central atom
resonance
situation in which one Lewis structure is insufficient to describe the bonding in a molecule, and the average of multiple structures is observed
Heisenberg uncertainty principle
states that it is not possible to know precisely both the velocity/momentum and the position of a particle at the same time
Which of the following correctly ranks, in order from least to greatest, the distance between bonded atoms of the same element?
triple bond, double bond, single bond. Theory predicts that as the bond strength increases (by adding more bonds), the distance between the atoms decreases. Since this question asked about the weakness, not the strength, this is the correct choice.
lone pair
two (a pair of) valence electrons that are not used to form a covalent bond
wave function
describes how the electrons move within an atom.
Lewis structure
diagram showing lone pairs and bonding pairs of electrons in a molecule or an ion
Cr₂O₇²⁻
dichromate
H₂PO₄⁻
dihydrogen phosphate
Write the name for N2O.
dinitrogen monoxide
quantum mechanics
field of study that includes quantization of energy, wave-particle duality, and the Heisenberg uncertainty principle to describe matter.
formal charge
a charge on an atom as a result of taking the number of valence electrons on the neutral atom and subtracting the nonbonding electrons and the number of bonds (one-half of the bonding electrons)
electron density
a measure of the probability of locating an electron in a particular region of space, it is equal to the squared absolute value of the wave function.
electronegativity
a measure of the tendency of an atom to attract a bonding pair of electrons
nodal plane
a planar surface on which the probability of finding an electron is zero.
quantized
allowed to exist only at certain discrete (non-continuous) values.
bond angle
angle between any two covalent bonds that share a common atom
electron-pair geometry
arrangement around a central atom of all regions of electron density (bonds, lone pairs, or unpaired electrons)
molecular structure
arrangement of atoms in a molecule or ion
resonance hybrid
average of the resonance forms shown by the individual Lewis structures
strong base
base that reacts completely when dissolved in water to yield hydroxide ions
weak base
base that reacts only to a slight extent when dissolved in water to yield hydroxide ions
single bond
bond in which a single pair of electrons is shared between two atoms
triple bond
bond in which three pairs of electrons are shared between two atoms
Write the name for BCl3.
boron trichloride
Write the name for Cal2.
calcium iodide
Write the name for CaSO4.
calcium sulfate
CO₃²⁻
carbonate
Write the correct name for H2CO3.
carbonic acid
effective nuclear charge
charge that leads to the Coulomb force exerted by the nucleus on an electron, calculated as the nuclear charge minus shielding
complete ionic equation
chemical equation in which all dissolved ionic reactants and products, including spectator ions, are explicitly represented by formulas for their dissociated ions
net ionic equation
chemical equation in which only those dissolved ionic reactants and products that undergo a chemical or physical change are represented (excludes spectator ions)
balanced equation
chemical equation with equal numbers of atoms for each element in the reactant and product
ClO₃⁻
chlorate
ClO₂⁻
chlorite
CrO₄²⁻
chromate
Write the name for Cu3(PO4)2.
copper(II) phosphate
CN⁻
cyanide
precipitate
insoluble product that forms from reaction of soluble reactants
salt
ionic compound that can be formed by the reaction of an acid with a base that contains a cation and an anion other than hydroxide or oxide
Write the name for FeCl3.
iron(III) chloride
Why did the Bohr model of the atom ultimately fail?
it required knowing the position and momentum of an electron.
isoelectronic
group of ions or atoms that have identical electron configurations
octet rule
guideline that states main group atoms will form structures in which eight valence electrons interact with each nucleus, counting bonding electrons as interacting with both atoms connected by the bond
spin quantum number
has only two possible values (+1/2, -1/2) which indicate the two fundamental spin states of an electron in an orbital. ms.
When the gas HBr(g) is dissolved in water, the solution is called:
hydrobromic acid
A binary acid is comprised of:
hydrogen and one other nonmetallic element.
HCO₃⁻
hydrogen carbonate (bicarbonate)
HSO₄⁻
hydrogen sulfate (bisulfate)
When the gas H2S(g) is dissolved in water, the solution is called:
hydrosulfuric acid
OH⁻
hydroxide
ClO⁻
hypochlorite
Write the name for Mg3N2.
magnesium nitride
hypervalent molecule
molecule containing at least one main-group element that has more than eight electrons in its valence shell
free radical
molecule that contains an odd number of electrons
f orbital
multilobed region of space with high electron density, describes orbitals with l = 3. An electron in this orbital is called an f electron
NO₃⁻
nitrate
NO₂⁻
nitrite
coefficient
number placed in front of symbols or formulas in a chemical equation to indicate their relative amount
valence shell
outermost shell of electrons in a ground-state atom; for main group elements, the orbitals with the highest n level (s and p subshells) are in the valence shell, while for transition metals, the highest-energy s and d subshells make up the valence shell; for inner transition elements, the highest s, d, and f subshells are included.
C₂O₄²⁻
oxalate
ClO₄⁻
perchlorate
MnO₄⁻
permanganate
orbital diagram
pictorial representation of the electron configuration showing each orbital as a box and each electron as an arrow.
Write the name for NaCl
sodium chloride
Pauli exclusion principle
specifies that no two electrons in an atom can have the same value for all four quantum numbers.
s orbitals are what shape?
spherical region of space with high electron density, describes orbitals with l=0. An electron in this orbital is called an s electron.
radial nodes
spherical region where the electron is not likely to be found.
molecular structure
structure that includes only the placement of the atoms in the molecule
product
substance formed by a chemical or physical change; shown on the right side of the arrow in a chemical equation
acid
substance that produces H₃O⁺ when dissolved in water
base
substance that produces OH⁻ when dissolved in water
reactant
substance undergoing a chemical or physical change; shown on the left side of the arrow in a chemical equation
SO₃²⁻
sulfite
Which of the following elements is a p-block element?
sulfur
Lewis symbol
symbol for an element or monatomic ion that uses a dot to represent each valence electron in the element or ion
chemical equation
symbolic representation of a chemical reaction
principal quantum number (n)
symbolized by n, indicates the main energy level occupied by the electron. positive integers (1,2,3...)
bond angle
the angle formed by two bonds to the same atom
solubility
the extent to which a substance may be dissolved in water or any solvent
probability maxima
the large "hills" on the graph.
what is an orbital?
the probability of finding an electron in a region.
magnetic quantum number (ml)
the quantum number that indicates the orientation of an orbital around the nucleus; orbitals having different values of ml but the same subshell value of l have the same energy (are degenerate), but this degeneracy can be removed by application of an external magnetic field. (l, l-1,...,-l)
angular momentum quantum number (l)
the quantum number that indicates the shape of an orbital. (0,1,2...n-1)
steric number (SN)
the sum of the number of atoms bonded to a central atom plus the number of lone pairs of electrons on the central atom
valence shell electron pair repulsion (VSEPR) theory
theory used to predict the bond angles in a molecule based on positioning regions of high electron density as far apart as possible to minimize electrostatic repulsion
resonance forms
two or more Lewis structures that have the same arrangement of atoms, but different arrangements of electrons
combustion reaction
vigorous redox reaction producing significant amounts of energy in the form of heat and, sometimes, light
molecules
well defined groups of atoms that are chemically bonded together in specific ratios.
electron spin
A property of the electron that makes it behave as though it were a tiny magnet. The electron behaves as if it were spinning on its axis; electron spin is quantized.
Choose all of the following atoms and/or ions that are isoelectronic with Br+.
As- Se
If a chemical is splashed or spilled into the eyes, they should be held open and rinsed continuously at the eyewash station for how long?
At least fifteen minutes
Write the formula for phosphorus pentafluoride.
PF5
Write the formula for chromium(III) chloride.
CrCl3
What type of reaction is NaOH+HCl--NaCl+H₂O?
Double Replacement
Which option correctly ranks the atoms from smallest to largest atomic radius?
F, N, P, P3-. Atomic radius decreases from left to right across the periodic table and increases from top to bottom. Additionally, an anion is always larger than its neutral parent atom. Fluorine is closest to the top right of the periodic table and is the smallest atom listed. Nitrogen is to the left of fluorine; its smaller effective nuclear charge results in a nitrogen atom having a larger radius than a fluorine atom. Phosphorus is below nitrogen; the increased shielding between the outermost electrons and nucleus due to the additional energy level results in a phosphorus atom having a larger radius than a nitrogen atom. Phosphide ion has three more electrons than phosphorus. With each additional electron, there is greater repulsion among the electrons and a decrease in the effective nuclear charge, both of which contribute to phosphide ion being larger than its parent atom, phosphorus.
Write the formula for mercury(II) oxide.
HgO
What is the name of the compound HI?
Hydroiodic acid
single replacement of active metal with water
Metal + H₂O --> Metal hydroxide + H₂
Based on their positions in the periodic table, arrange the atoms in order of increasing radius
Mg Ca Rb Cs
Write the formula for magnesium phosphate.
Mg3(PO4)2
Given their positions within the periodic table, which atom is more electronegative? (N or K)
N. N is further to the right on the periodic table than K.
In naming chemical substances, when is the suffix -ous used?
The suffix is given to an acid in which the anion has a name ending in -ite.
Which option is not a principal characteristic of atoms and molecules that scientists use to predict chemical behavior?
The use of a chemical, including both its application and frequency of application, is dependent upon the substance's chemical characteristics.
Which of the following statements about molecular polarity is not correct?
There is no net dipole moment for the water molecule because the two bond dipoles that result from the H-O bonds effectively cancel out each other. Remember that water has two lone electron pairs. This causes the molecule to be bent. Therefore, the bond polarities do not cancel out, and the molecule is polar.
