General Chemistry I: CH. 6 & 7 Review
If a nitrogen atom has four covalent bonds, what will be its formal charge? Report your answer using an integer without any decimal places. Provide your answer below:
+1 If a nitrogen has four bonds, it will contribute four electrons to the Lewis structure, which is one less than its typical valence of five. That means a formal positive charge.
H2(g) + F2(g) --> 2HF(g) bond energies: (H-H)= 432 kJ (F-F)= 154 kJ (H-F)= 565 kJ What is the enthalpy of the reaction using bond energies? Your answer should have three significant figures.
-544 kJ The enthalpy of the reaction is given by H= Sum of bonds broken− Sum of bonds formed H=[ (H - H) + (F - F) ] − 2 (H - F) H=(432 + 154) − 2 (565) H= −544 kJ Notice that the number of bonds (used as a coefficient) is an exact value, so it does not constrain the number of significant figures.
2CO (g) + O2 (g) --> 2CO2 (g) bond energies: (C ≡ O) = 1074 kJ (O = O) = 499 kJ (C = O) = 802 kJ What is the enthalpy of the reaction using bond energies? Your answer should have three significant figures.
-561 kJ ................ Before solving this problem, be sure to draw out the structures of CO, O2, and CO2. The structures are as follows (omitting lone pairs for simplicity): C≡O O=O O=C=O Note that CO2 has 2 C=O double bonds per molecule. The enthalpy of the reaction can be calculated using the enthalpies of the bonds broken and formed in the reaction: ΔH=∑D bonds broken − ∑D bonds formed ΔH= [2(C≡O)+(O=O)]−4(C=O) ΔH= 2(1074 kJ)+(499 kJ)−4(802 kJ) ΔH= −561 kJ Notice that coefficients in stoichiometric equations (indicating numbers of moles) are exact, so they do not constrain the number of significant figures.
Use the information below to answer the question that follows. N2(g) + 3H2(g) ⟶ 2NH3(g) Bond energies: (N≡N)= 941 kJ (H−H)= 436 kJ (N−H)= 391 kJ What is the enthalpy of the reaction using bond energies, in kilojoules? Round your answer to the nearest whole number. Provide your answer below:
-97 kJ Before solving this problem, be sure to draw out the structures of N2, H2 and NH3. Doing this, you should find that this reaction involves the dissociation of a N≡N bond and three H−H bonds (one in each H2 molecule), as well as the formation of six N−H bonds (three in each molecule of NH3). The enthalpy of the reaction is given by the following: ΔH=∑Dbonds broken − ∑Dbonds formed ΔH= [(N≡N) + 3 (H−H)] − 6 (N−H) ΔH= 941 kJ + (3×436 kJ) − (6×391 kJ) ΔH= −97 kJ Notice that the number of bonds (used as a coefficient) is an exact value, so it does not constrain the number of significant figures.
Which of the following statements about covalent bonding is/are generally true? Select all that apply: -Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves. -Covalent bonds tend to form between metals and nonmetals. -Nonmetal atoms frequently form covalent bonds with other nonmetal atoms. -Compounds that contain covalent bonds have physical properties similar to ionic compounds.
-Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves. -Nonmetal atoms frequently form covalent bonds with other nonmetal atoms. Covalent bonds are formed between two atoms when both have similar tendencies to attract electrons to themselves. Also, nonmetal atoms frequently form covalent bonds with other nonmetal atoms. For example, two hydrogen atoms bond covalently to form an H2 molecule; each hydrogen nucleus in this molecule is attracted to two electrons, giving each atom the same number of valence electrons as the noble gas He. Compounds that contain covalent bonds exhibit vastly different physical properties than ionic compounds; covalent compounds generally have much lower melting and boiling points than ionic compounds and many covalent compounds are liquids or gases at room temperature.
We can predict the number of bonds an atom can form by counting: (select all that apply) Select all that apply: -the number of core electrons needed to form an octet -the number of additional electrons needed to form an octet -the number of valence electrons -The total number of core electrons.
-the number of additional electrons needed to form an octet -the number of valence electrons We can predict the number of bonds an atom can form by counting the number of electrons needed to form an octet, or the number of valence electrons in the atom.
The sum of formal charges of all atoms in a neutral molecule should be: Report your answer as a whole number without any decimal places. Provide your answer below:
0 The sum of the formal charges on all the atoms in a neutral molecule should be 0. However, each individual atom can bear a positive or negative charge. The sum of these positive and negative charges makes up the formal charge of the molecule.
What is the formal charge of the carbon atom in the carbon dioxide molecule, above? Select the correct answer below: 0 1 2 3
0 formal charge=4−(0 lone pair electrons+4 bonded electrons)=0 To calculate the formal charge of the carbon atom, you need to subtract the number of electrons in bonds from the number of valence electrons. You can get the number of valence electrons from the periodic table. Then you can count the number of bonds to get the number of bonded electrons. This gives you: formal charge=valence electrons−number of electrons seen in the structure
If two lattice structures have the same interionic distance, but the first lattice contains ions of 1+ and 1− charge, while the second contains ions of 2+ and 2− charge, what will be the ratio of their lattice energies? Select the correct answer below: 1 to 2 2 to 1 1 to 4 4 to 1
1 to 4 Since each charge doubles, the lattice energy must quadruple.
If a nitrogen atom has four covalent bonds, what will be its formal charge? Select the correct answer below: 1− 0 1+ 2+
1+ If a nitrogen has four bonds, it will contribute four electrons to the Lewis structure, which is one less than its typical valence of five. That means a formal positive charge.
What is the charge on the oxygen atom in carbon monoxide? Select the correct answer below: 1− 0 1+ 2+
1+ Oxygen will contribute five electrons to the Lewis structure, three in the triple bond and one lone pair. That's one less than its typical valence, so it will bear a formal positive charge.
Given the electron configuration of Cl ([Ne]3s2 3p5), determine the charge of the anion. Your answer should include only a number and a sign (+ or −). Provide your answer below:
1-
Given the electron configuration of Cl([Ne]3s2 3p5), determine the charge of the anion. Your answer should include only a number and a sign (+ or −). Provide your answer below:
1- Given the electron configuration of Cl, we can see how many electrons it would take to make the noble gas configuration nearest (Argon). It would require 1 electron which means that the charge on Cl is 1−.
What is the electron configuration for Zn2+? Select the correct answer below: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 1s2 2s2 2p6 3s2 3p6 3d10 1s2 2s2 2p6 3s2 3p6 3d12 none of the above
1s2 2s2 2p6 3s2 3p6 3d10 The Zn cation loses 2 electrons to form Zn2+. The electron configuration of Zn is 1s22s22p63s23p64s23d10. Note that because zinc is a transition metal, it will lose the 4s electrons before the 3d electrons. Therefore, the electron configuration of Zn2+ is 1s22s22p63s23p63d10.
What is the electron configuration for the core electrons in bromine? Select the correct answer below: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 4s2 3d10 4p5 1s2 2s2 2p6 3s2 3p6 1s2 2s2 2p6 3s2 3p6 3d10
1s2 2s2 2p6 3s2 3p6 3d10 Bromine's full electron configuration is 1s22s22p63s23p64s23d104p5. From this configuration, we separate the valence electrons (4s24p5) from all of those that constitute full principal energy level shells. Therefore, the configuration of core electrons in bromine is written as 1s22s22p63s23p63d10. These are the core electrons of bromine, which are virtually unreactive as they constitute full octets.
What is the electron configuration for V2+ ? Select the correct answer below: 1s2 2s2 2p6 3s2 3p6 4s2 3d1 1s2 2s2 2p6 3s2 3p6 3d3 1s2 2s2 2p6 3s2 3p6 3d5 1s2 2s2 2p6 3s2 3p6 4s2 3d3
1s2 2s2 2p6 3s2 3p6 3d3 .......... The electron configuration for V is [Ar]4s23d3. Two electrons are removed to form V2+. Note for transition metals, electrons are lost from the s subshell before the d subshell. Therefore, the electron configuration for V2+ is [Ar]3d3, or 1s22s22p63s23p63d3.
What is the electron configuration for Fe3+? Select the correct answer below: 1s2 2s2 2p6 3s2 3p6 3d5 1s2 2s2 2p6 3s2 3p6 3d6 4s2 1s2 2s2 2p6 3s2 3p6 3d6 4s1 1s2 2s2 2p6 3s2 3p6 3d8
1s2 2s2 2p6 3s2 3p6 3d5 ............ The Fe cation loses 3 electrons so 1s22s22p63s23p63d5 from 1s22s22p63s23p63d64s2.
What is the ground state configuration of calcium? (Ca) Provide your answer below:
1s2 2s2 2p6 3s2 3p6 4s2
What is the electron configuration of tellurium (Te)? Provide your answer below:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p4 ............. Tellurium is in the fifth period and a member of group 16. The atomic number of tellurium is 52 so there must be 52 electrons in the electron configuration for a neutral tellurium atom. Therefore, the electron configuration for tellurium is 1s22s22p63s23p64s23d104p65s24d105p4 Alternatively, this can be expressed as [Kr]5s24d105p4.
What is the electron configuration for Zr? Provide your answer below:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4p2
What is the electron configuration of strontium? Provide your answer below:
1s2 2s2 2p6 3s2 3p6 4s2 4p6 5s2 Strontium is the second element in the s block of period 5, so its two valence electrons will reside in the 5s orbital. Thus, the term 5s2 describes the valence shell of strontium. The complete electron configuration is 1s22s22p63s23p64s23d104p65s2, or equivalently [Kr]5s2
What are the core electrons of strontium? Select the correct answer below: 1s22s22p63s23p64s23d104p6 5s2 1s22s22p63s23p64s23d104p65s2 none of the above
1s22s22p63s23p64s23d104p6 ......... Strontium's full electron configuration is 1s22s22p63s23p64s23d104p65s2. To find its core electrons, we must separate the valence electrons (in this case, 5s2) from all of the complete principal energy level shells (the configuration of the closest noble gas). Thus we isolate the electron configuration of krypton, 1s22s22p63s23p64s23d104p6, from the full electron configuration of Sr. These are its core electrons, which are virtually unreactive as they constitute full octets.
How many bonds would nitrogen need to form to obtain an octet? Select the correct answer below: 1 2 3 4
3 Nitrogen would need 3 bonds to form an octet because it already has 5 electrons.
What charge cation will aluminum typically form? Your answer should be a whole number with a charge. Provide your answer below:
3+ Given that aluminum has three valence electrons, it will typically lose these three to form a 3+ cation and gain neon electron configuration.
The electron configuration for sodium is 1s22s22p63s1. Which subshell is said to contain the valence electron(s) for sodium? Select the correct answer below: 1s 3s 2p 2s
3s ............ For main group elements, the shell with the largest value of n is called the valence shell. In this case, the subshell with the largest value of n is the 3s subshell (n=3), and so the single valence electron in sodium is held in the 3s subshell
Typically if nitrogen has a positive formal charge, it is participating in ____ covalent bond(s). Select the correct answer below: 1 2 3 4
4
If carbon has four valence electrons, how many bonds will it tend to make? Select the correct answer below: 1 2 3 4
4 Carbon will make four more bonds in order to interact with four more electrons and fill its octet.
How many bonds would silicon need to form to obtain an octet? Select the correct answer below: 2 4 6 8
4 Silicon already has 4 valence electrons so 4 bonds are needed to be formed in order to obtain an octet.
Which is NOT a typical cation of chromium? Select the correct answer below: 2+ 3+ 5+ 6+
5+ Most transition metals will readily form 2+ and 3+ ions. The electron configuration for neutral chromium is 1s22s22p63s23p64s13d5. Chromium is a d-block transition metal, and so the valence electrons are removed from the s subshell before they are removed from the d subshell. Therefore, Chromium would lose its one s electron first and a d electron to form Cr2+, which is only stable in the absence of air. Chromium can also lose its one s electron and two more d electrons to become Cr3+, which is the most stable oxidation state for chromium. Chromium can also lose all the remaining valence electrons to become Cr6+. Chromium is seen in this oxidation state in chromium(VI) sulfide Cr2S3.
When drawing orbital diagrams, each orbital is represented as a box. For example, an s subshell is represented by 1 box, and a p subshell is represented by 3 boxes. How many boxes are required to depict an f subshell? Provide your answer below:
7 boxes ...... Each box represents an orbital, and an f subshell contains 7 orbitals, regardless of the principle quantum number. Therefore there seven boxes are required to depict an f subshell.
Based on the graph below, what is the bond length of H2 in picometers? Select the correct answer below: 0 74 −7.24×10^−19 −74
74 The lowest (most stable) energy occurs at a distance of 74 pm, which is the bond length observed for the H2 molecule.
How many valence electrons does an iron atom ( Fe) have?
8 Start by writing the electron configuration of the neutral atom: Fe:1s22s22p63s23p64s23d6 Recall that transition metals don't have "traditional" valence electrons. The valence electrons for a transition metal element are those of the highest ns and n−1d value, in this case those electrons in 4s and 3d. This means Fe has 8 valence electrons.
Which of the following best explains what resonance structures are? Select the correct answer below: -A molecule whose Lewis structure could be described by more than one resonance structure possesses an electronic structure equal to that of the most stable resonance form. -A molecule whose Lewis structure could be described by more than one resonance structure possesses an electronic structure equal to that of a combination of the resonance structures, with the more stable structures contributing more to the average structure. -A molecule whose Lewis structure could be described by more than one resonance structure possesses an electronic structure that fluctuates between the possible structures over time. -A molecule whose Lewis structure could be described by more than one resonance structure could have any of the different resonance structures. Each different resonance is a different compound.
A molecule whose Lewis structure could be described by more than one resonance structure possesses an electronic structure equal to that of a combination of the resonance structures, with the more stable structures contributing more to the average structure. Resonance structures all contribute to the overall electronic structure of a molecules. They do not fluctuate over time, and they do not represent exact structures of different compounds. Instead, for any given arrangement of atoms in a molecule, the most stable arrangement of multiple bonds and formal charges may not represent a single Lewis structure, but an average over multiple stable resonance structures.
Which of the following may contribute to the increased radius of an anion compared to parent atom? Select all that apply: -Additional electrons lead to more electron-electron repulsion, which will increase the average distances of all the outer orbitals from the nucleus. -Fewer protons lead to more electron-electron repulsion, which will increase the average distances of all the outer orbitals from the nucleus. -The charge of the nucleus decreases. -None of the above.
Additional electrons lead to more electron-electron repulsion, which will increase the average distances of all the outer orbitals from the nucleus. ................................... Anions are larger than their parent atoms due to the additional electrons. Since electrons are all negatively charged, they all repel each other and spread further apart, increasing the radius of the ion. The charge of the nucleus does not change because anions are not formed by changing the number of protons in the nucleus - only by changing the number of electrons. The *effective* nuclear charge may decrease, but this is a form of electron-electron repulsion.
Which element, when it loses 3 electrons, will have the electron configuration 1s2 2s2 2p6? Select the correct answer below: B Al Na Mg
Al Aluminum is the third element in period 3 so when it loses three electrons it will have neon electron configuration.
Which of the following is true? Select the correct answer below: -If the Lewis structure must have nonzero formal charges, the arrangement with the smallest nonzero formal charges is preferable. -A molecular structure in which all formal charges are zero is preferable to one in which some formal charges are not zero. -Lewis structures are preferable when adjacent formal charges are zero or of the opposite sign. -All of the above
All of the above All of the above are guidelines to be considered when choosing the preferred Lewis structure.
Which of the following is a characteristic of ionic solids? Select the correct answer below: Their ionic bonds are very strong Ionic solids are poor conductors of electricity Ionic solids dissolve easily in water All of the above
All of the above The properties of ionic compounds shed some light on the nature of ionic bonds. Ionic solids exhibit a crystalline structure and tend to be rigid and brittle; they also tend to have high melting and boiling points, which suggests that ionic bonds are very strong. Ionic solids are also poor conductors of electricity for the same reason. Most ionic solids, however, dissolve readily in water.
what is the difference between an anion and cation?
Anion= is a molecule or a group of molecules with one or more negative electric charges. Cations= have one or more positive charges attached to them
Which ion is isoelectronic with xenon? Select the correct answer below: Sr2+ Xe+ Ba2+ I+
Ba2+ If barium loses its two 6s electrons it will lose a shell and attain xenon electron configuration.
Which pair of elements will NOT form an ionic compound? Select the correct answer below: Mg and O Li and F Ca and Cl C and Br
C and Br Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions. Carbon will not ionize very easily, so carbon and bromine will form a covalent compound.
Which molecule will have a triple bond? Select the correct answer below: C2H2 C2H4 C2H6 C3H6
C2H2 C2H2 must have a triple bond between the carbons in order for the carbon atoms to fill their octet. C2H4 contains a double bond between the carbon atoms to maintain the octet on each carbon. C2H6 contains a single bond between the carbon atoms to maintain the octet on each carbon. C3H6 contains a double bond between two carbon atoms and a single bond between the other two carbon atoms. This double bond is interchangeable between carbon atoms and maintains the octet for each carbon.
Which of the following species has the smallest radius? Select the correct answer below: C4+ B3+ Be2+ Li+
C4+ These species are isoelectronic, and carbon has the most protons, so it will attract the remaining two core electrons the most.
Use the figure provided to determine which of the following is the least polar. *LEAST POLAR = HIGHEST ELECTRONEGATIVITY* Select the correct answer below: KCl MgS CO LiF
CO ................. The relative polarities of diatomic compounds can be approximated by calculating the electronegativity difference (ΔEN) between the two bonding atoms. Using the table above these differences can be calculated as follows. KClMgSCOLiFΔEN=3.0−0.8ΔEN=2.5−1.2ΔEN=3.5−2.5ΔEN=4.0−1.0=2.2=1.3=1.0=3.0 Of the compounds listed, CO or carbon monoxide has the smallest electronegativity difference between the two bonding atoms. Therefore, CO is the least polar.
The element with the highest electronegativity is: Report your answer as an element symbol. Provide your answer below:
F Fluorine is at the upper right hand corner of the table, excluding the noble gases, which do not receive electronegativity values.
_____ is the calculated charge on an atom in a covalent molecule. Select the correct answer below: Ionic charge Atomic charge Valence charge Formal charge
Formal charge The formal charge of an atom in a covalent molecule is a calculated charge, based on the hypothetical case in which all bonding electrons are redistributed evenly.
List S, Fr, Rb, F, and In in order of largest to smallest covalent radius. Select the correct answer below: F, S, In, Rb, Fr F, S, Rb, In, Fr Fr, In, Rb, S, F Fr, Rb, In, S, F
Fr, Rb, In, S, F BECAUSE LOWEST/LEFT= LARGEST TO HIGHEST/RIGHT=SMALLEST
Which of the following explains why there is a decrease in ionization energy for the group containing oxygen in the first four periods compared to the group containing nitrogen? Select the correct answer below: Group 15 elements have completely filled p orbitals. Group 15 elements have half-filled p orbitals. Group 16 elements have completely filled p orbitals. Group 16 elements have half-filled p orbitals.
Group 15 elements have half-filled p orbitals. ................... There is a decrease in ionization energy between groups 15 and 16 in the first four periods because group 15 elements have half-filled p orbitals, while group 16 elements have an extra electron that must share an orbital with another electron. This additional repulsion destabilizes the electron beyond what is compensated by the increase in Zeff. This increased destabilization results in a decrease in ionization energy.
Which of the following will have the greatest electronegativity? Select the correct answer below: H Li Na K
H
Which molecule will have a double bond? Select the correct answer below: CO CCl4 OF2 H2CO
H2CO In H2CO, carbon and oxygen form a double bond in order to satisfy the octet rule. The 2 hydrogen attach to the 2 carbon electrons remaining, creating only 2 single bonds.
Use the figure provided to determine which of the following has bonds with the greatest bond-polarity. Select the correct answer below: HCl NO2 NH3 H2O
H2O Calculating the difference between the electronegativities for each element of each molecules, we find that H and O have the greatest difference, so H2O has bonds with the greatest polarity.
Which molecule has the most lone pairs (unmatched pairs)? Select the correct answer below: CH4 NH3 H2O HF
HF The fluorine atom will have three lone pairs, whereas water has two, ammonia has one, and methane has none.
Which element has the smallest covalent radius on the periodic table? Select the correct answer below: H He Fr Lr
He Helium is in the upper right-hand corner of the periodic table, which means it has only one shell and is even smaller than hydrogen because of the additional proton in the nucleus, causing the radius to contract further.
Which of the following species has the largest radius? Select the correct answer below: Br Br− I I−
I− Iodine is larger than bromine in general, due to an additional shell. Also, the iodide ion is larger than neutral iodine due to the additional electron and the resulting enhanced repulsion.
Which of the following elements has the lowest first ionization energy? Select the correct answer below: Na K Mg Ca
K Potassium is the closest to the lowest left corner of the periodic table, so it is the largest atom and has only one valence electron. This makes it easiest to ionize.
Which of the following has the highest second ionization energy (IE2)? Select the correct answer below: Li K Na Cs
Li The elements listed are all in first group of the periodic table. Ionization energies tend to increase going up a group in the periodic table. Of the elements listed, the element with the largest second ionization energy is lithium because it is the closest to the top of the periodic table.
Which of the following has the greatest lattice energy? Select the correct answer below: K2O Rb2S Li2O They all have the same lattice energy.
Li2O Because lattice energy is the measure of the strength of the attraction between the positive and negative ions in an ionic compound, the larger the radius between the two ions, the smaller the lattice energy. We know atomic radius increases as we move to the left and down the periodic table. K,Li, and Rb all have a charge of +1. Li is the highest on the periodic table, so it will have the smallest radius, and thus the greatest lattice energy.
Who is credited with deriving the electronegativity values of the periodic table? Select the correct answer below: Alfred Nobel Linus Pauling John Dalton Antoine Lavoisier
Linus Pauling Linus Pauling derived the electronegativity values for each element in the periodic table.
Which species has the smallest radius? Select the correct answer below: Mg2+ Mg+ Mg Mg−
Mg2+ If magnesium loses two electrons, it will lose its entire valence shell, and therefore dramatically reduce in size.
What is the symbol for the following ion electronic structure: [He]2s22p6 with an atomic number of 12? Select the correct answer below: Na+ K+ Ca2+ Mg2+
Mg2+ ......... Atomic number 12 corresponds to Mg but there are 2 less electrons than Mg usually has (lost electrons = cation) so: Mg2+.
Which molecule will have a triple bond? N2 O2 F2 Cl2
N2 Nitrogen atoms have three unpaired electrons, so when they bond with one another they form three covalent bonds.
Which molecule will have the strongest bond? Select the correct answer below: F2 Cl2 O2 N2
N2 ...... A nitrogen molecule has a triple bond, while the rest have double or single bonds.
Which molecule will have the strongest bond? Select the correct answer below: F2 Cl2 O2 N2
N2 ............. A nitrogen molecule has a triple bond, while the rest have double or single bonds.
Which of the following bonds in a molecule is the strongest? N−O N=O N−S N=S
N=O Double bonds are typically stronger than single bonds between the same two atoms. When one atom bonds to various atoms in a group, the bond strength typically decreases as we move down the group. Thus, the N=O bond is the strongest of the four.
Which molecule contains only single bonds? Select the correct answer below: CO2 NH3 HCN C2H4
NH3 CO2 and C2H4 contain double bonds, while HCN contains a triple bond, but ammonia has only single bonds.
Of the following choices, the largest decrease in ionic radius occurs when __________. Select the correct answer below: Mg becomes Mg+ Na becomes Na+ Ne becomes Ne+ F becomes F+
Na becomes Na+ When sodium loses its valence electron, it will lose an entire shell, thus dramatically reducing its radius, more so than the other listed elements.
Which of the following has the smallest atomic radius? Select the correct answer below: Ne Al Mg Ar
Ne Atomic radius increases when moving from top to bottom and right to left on the periodic table. Neon has the smallest atomic radius of those listed as choices.
Identify the compound with the pure covalent bond. Select the correct answer below: O2 HCl SO2 all of the above
O2 O2 has a pure covalent bond because the atoms it contains are identical and thus the electrons in this bond are shared equally.
Which of the following elements has the smallest covalent radius? Select the correct answer below: Ge Si As P
P Phosphorus is the closest to the top right of the periodic table, so it will have the smallest radius of the four.
Which of the following elements has the largest covalent radius? Select the correct answer below: Pb Sb Br Bi
Pb Atomic radius increases when moving from top to bottom and right to left on the periodic table. Lead is the lowest and the furthest left on the table of these four elements, so it is expected to have the largest radius.
When drawing the Lewis structure for a molecule, after drawing the skeletal structure and distributing all of the electrons around the terminal atoms, what actions should be taken if the central atom does not have a complete octet? Select the correct answer below: -Move a lone pair electrons from one or more outer atoms to the central atom. -Rearrange lone pairs of electrons from the outer atom(s) to form double or triple bonds to the central atom. -Rearrange lone pairs of electrons around the central atom to form double or triple bonds to an outer atom or atom(s). -Add electrons to the central atom, and count how many were added so the charge of the molecule or ion can be adjusted.
Rearrange lone pairs of electrons from the outer atom(s) to form double or triple bonds to the central atom. When drawing the Lewis structure of a molecule, if the central atom lacks an octet, we can move lone pairs of electrons on an outer atom to form a higher order bond (double or triple bond) with the central atom. This preserves the number of electrons for the outer atom so that the octet rule is still satisfied, and increases the number of electrons for the central atom, because shared electron pairs in a bond count as two electrons for both atoms when counting towards the octet rule.
Which of the following is an exception to the octet rule? Select the correct answer below: -Carbon in CO2 -Oxygen in H2O -Sulfur in SO2−4 -Phosphorus in PH3
Sulfur in SO2−4 Sulfur in SO2−4 is an exception to the octet rule. In this case, sulfur is said to have an expanded octet because it has more than 8 electrons in its valence shell. The Lewis structure for SO2−4 contains two S=O double bonds and two S−O single bonds. These bonds are all covalent bonds, and so the central sulfur atom shares these electron pairs with the oxygen atoms to fill its valence shell. There are 8 electrons in the two S=O double bonds and 4 electrons in the two S−O single bonds. Therefore, the central sulfur atom has 12 electrons in its valence shell.
Which of the following statements about deciding between resonance structures with formal charges is correct? Select the correct answer below: -The structure with the negative formal charges on the least electronegative atom is preferred. -The molecular structure where all formal charges are zero is preferred. -If there are nonzero formal charges, the arrangement with the largest absolute value formal charges is preferred. -All of the above
The molecular structure where all formal charges are zero is preferred. The structure that is preferred is the one where all formal charges are zero. This represents the least separation of charge.
The number of electrons in the electron configuration for a neutral element is equal to the elements atomic number. How does the total number of electrons change when an element forms a positive ion? Select the correct answer below: The number of electrons increases when forming a positive ion. The number of electrons decreases when forming a positive ion. The number of electrons does not change when forming a positive ion. None of the above.
The number of electrons decreases when forming a positive ion. .............. When an element forms a positive ion, the total number of electrons must decrease.
Hund's rule states that: Select the correct answer below: You must place one electron in each orbital in a subshell before doubling up. Orbitals will be filled in order of increasing energy. No two electrons in an atom can have the same set of quantum numbers. None of the above
You must place one electron in each orbital in a subshell before doubling up. ............................. When filling a particular subshell, Hund's rule tells us that we must place one electron in each individual orbital before placing a second one in any of the orbitals, as that is the process that will maintain the lowest energy possible.
What is the electron configuration of Ge? Provide your answer below:
[Ar] 4s2 3d10 4p2 ............ Germanium contains 32 protons and electrons and using the electron configuration order (1s,2s,2p,3s,3p,4s,3d,4p,5s,4d,5p,6s,4f,5d,6p,7s,5f,6d,7p,8s), we can fill up to 32 which gives us the correct answer. Therefore the electron configuration for germanium is 1s22s22p63s23p64s23d104p2.
What is the abbreviated electron configuration of Mn^2+? Provide your answer below:
[Ar]3d^5 The abbreviated electron configuration of Mn is [Ar]4s2 3d5. Because Mn is a d-block transition metal, the electrons of the s subshell are removed before the (n−1)d electrons. Thus the abbreviated electron configuration for Mn2+ is [Ar]3d5.
What is the electron configuration of the As^3+ cation? Provide your answer below:
[Ar]4s^2 3d^10 Given the electron configuration of As([Ar]4s2 3d10 4p3), we remove electrons of the highest n value first. Once the 3 valence electrons are removed from the 4p subshell, we are left with [Ar]4s2 3d10.
Using core notation, what is the abbreviated electron configuration of yttrium (Y)?
[Kr] 5s2 4d1 The noble gas from the row above is krypton, so we will need krypton core plus the valence electrons in the 5s and 4d orbitals.
What is the electron configuration for Na+? Provide your answer below:
[Ne] The electron configuration of Na is [Ne]3s1. If we remove all of the valence electrons, we are left with [Ne] as the electron configuration of the Na+ cation. Alternately, the ground state configuration of the Na+ cation can be written as: 1s22s22p6
What is the abbreviated electron configuration of silicon? Provide your answer below:
[Ne] 3s2 3p2 The noble gas from the row above is neon, so we will need neon core plus the valence electrons 3s2 and 3p2.
What is the electron configuration of Cl−? Provide your answer below:
[Ne]3s2 3p6 The electron configuration of Cl− would be one more electron than the original configuration of Cl so the answer is [Ne]3s2 3p6
What forms when three electron pairs are shared by a pair of atoms? Select the correct answer below: a single bond a double bond a triple bond none of the above
a triple bond A triple bond forms when three electron pairs are shared by a pair of atoms.
When constructing electron configurations for ions, we ______ electrons for a negative ion. Select the correct answer below: multiply subtract add none of the above
add .......... When constructing electron configurations for ions, we add electrons for a negative ion.
For the purposes of determining electron configuration of ions, when electrons are added to a neutral atom, they will inhabit orbitals according to: Select the correct answer below: the Pauli exclusion principle the Aufbau principle Hund's rule all of the above
all of the above Adding additional electrons to neutral atom to form a negative ion follows the same principles that affect the electron configuration of a neutral atom.
To calculate the formal charge on an atom we must know: Select the correct answer below: -the number of valence electrons it possesses -the number of lone pairs surrounding the atom -the number of covalent bonds the atom is participating in -all of the above
all of the above The formal charge will be equal to the valence electrons minus the number of electrons in lone pairs minus half the bonding electrons, so we will need to know all of these values.
An atom will have a formal charge if it: Select the correct answer below: -gains an electron -loses an electron -is surrounded by a number of electrons that is different from its valence -all of the above
all of the above When an atom is surrounded by a number of electrons different from its valence, it will bear a formal charge. The difference in number of electrons can be either an excess or loss.
In an orbital diagram, such as the one below, each small box represents which of the following? Select the correct answer below: a shell a subshell an individual orbital an individual electron
an individual orbital ................ Each box represents one orbital, each of which can hold two electrons.
Choose the pair of words or phrases that best completes the sentence below. Isoelectronic species have radii that vary with __________ even though they have the same number of __________. Select the correct answer below: the number of electrons; protons atomic number; electrons atomic number; neutrons the number of electrons; neutrons
atomic number; electrons Isoelectronic species are those with the same number of electrons, such as Ne, Na+, and Mg2+. They have radii that depend on the number of protons in the nucleus, hence depend on the atomic number.
The sum of the formal charges of all atoms in an ion should always be equal to the: Select the correct answer below: -formal charge of the central atom. -formal charge of the most electronegative atom. -charge of that specific ion. -formal charge of the least electronegative atom.
charge of that specific ion
The electrons most responsible for shielding in an atom are the __________.
core electrons
Which of the following describes how tightly an atom attracts electrons in a bond? Select the correct answer below: electronegativity ionization energy atomic radius electron affinity
electronegativity .............. Electronegativity describes how tightly an atom attracts electrons in a bond.
In a polar covalent bond: Select the correct answer below: -electrons are shared unevenly -electrons are shared evenly -electrons are transferred from one atom to another -depends on the elements involved in the bond
electrons are shared unevenly In a polar bond, electrons are still shared, but unevenly, as one atom will pull them more closely than the other.
When the bonds in the products are weaker than those in the reactacts, the reaction is: Select the correct answer below: endothermic neutral exothermic none of the above
endothermic Bond dissociation energy is the energy required to separate a pair of bonded atoms. If the bonds of the products are weaker than the bonds in the reactacts, then heat is absorbed meaning H is positive and the reaction is endothermic.
When covalent bonds break: Select the correct answer below: energy is absorbed energy is released mass is gained mass is lost
energy is absorbed Energy must be added to break covalent bonds (endothermic), whereas forming covalent bonds releases energy (exothermic).
When covalent bonds form: Select the correct answer below: -energy is absorbed -energy is released -mass is gained -mass is lost
energy is released Since the formation of covalent bonds brings the system to a lower energy, that quantity of energy is released from the system when the bonds form, making their formation exothermic.
If the bonds in the products are stronger than the bonds in the reactants, the reaction must be: Select the correct answer below: exothermic endothermic energetically unfavorable spontaneous
exothermic ....... If the bonds are stronger in the products, they must sit at a lower potential energy and thus energy must have been released in forming them.
When the bonds in the products are stronger than the bonds in the reactants, the reaction is: Select the correct answer below: endothermic neutral exothermic none of the above
exothermic ............. Bond dissociation energy is the energy required to separate a pair of bonded atoms. If the bonds of the products are stronger than the bonds in the reactacts, then heat is released meaning H is negative and the reaction is exothermic.
The element with the highest electronegativity is: Select the correct answer below: helium neon carbon fluorine
fluorine Fluorine is at the upper right hand corner of the table, excluding the noble gases, which do not receive electronegativity values.
(Number of valence shell electrons - number of lone pair electrons - 12 bonding electrons) is the formula for: Select the correct answer below: -ionic charge -atomic charge -valence charge -formal charge
formal charge (number of valence shell electrons - number of lone pair electrons - 12 bonding electrons) is the formula for formal charge.
The covalent radius ______ as the distance of the outermost electrons from the nucleus ________. Select the correct answer below: increases, increases stays the same, increases increases, decreases decreases, increases
increases, increases Covalent radius is defined as one-half the distance between the nuclei of two identical atoms when they are joined by a covalent bond. The covalent radius increases as the distance of the outermost electrons from the nucleus increases.
Which of the following has the last electron added into the f orbital? Select the correct answer below: main group elements transition elements inner transition elements all of the above
inner transition elements Inner transition elements are metallic elements in which the last electron added occupies an f orbital. The valence shells of the inner transition elements consist of the (n - 2)f, the (n - 1)d, and the ns subshells.
For similar types of bonds, bond length and bond energy are: Select the correct answer below: directly proportional inversely proportional unrelated depends on the molecule
inversely proportional ......... For similar types of bonds, as the bond length increases, the bond energy decreases, and vice versa.
In general, when the absolute value of the difference in electronegativity of two bonded atoms is above 1.8, the bond is considered to be __________. Select the correct answer below: pure covalent polar covalent ionic
ionic ................... ionic = electronegativity of TWO bonded atoms is ABOVE 1.8 ............ Typically when the difference in electronegativity between two bonded atoms is greater than 1.8, the bond is considered to be ionic.
The greater the electronegativity difference, the more the bond will exhibit: Select the correct answer below: covalent character ionic character metallic character depends on the elements
ionic character .................... As the difference in electronegativity increases, the ionic character of the bond increases.
When an atom gains an electron to form an anion, the resulting radius will always be: Select the correct answer below: larger smaller identical depends on the element
larger Additional electrons result in greater electron repulsion and a reduced effective nuclear charge felt per electron, which results in an expansion of the radius.
The paradox concerning light emitted from atoms and molecules was addressed by: Select the correct answer below: blackbody radiation photoelectric effect line spectra none of the above
line spectra .......... The paradox concerning light emitted from atoms and molecules was addressed by line spectra.
Single bonds are ________________ and _________________ than triple bonds. Select the correct answer below: shorter, stronger shorter, weaker longer, stronger longer, weaker
longer, weaker ..................... The shorter the bond is, the stronger it is, and bond length will decrease as we add more bonds between two atoms. Thus single bonds are longer and weaker than triple bonds.
Which of the following is an example of line spectra? Select the correct answer below: neon "OPEN" sign flashlight street lamp all of the above
neon "OPEN" sign ....... Neon signs are examples of line spectra.
Covalent bonds are formed most frequently between: Select the correct answer below: -metals -nonmetals -metals and nonmetals -all elements have an equal tendency
nonmetals Nonmetals are most likely to form covalent bonds. Ionic bonds are formed when one atom (generally a metal) transfers an electron to another atom (generally a nonmetal).
What are pictorial representations of electron configurations? Select the correct answer below: valence electrons orbital diagrams aufbau diagrams quantum numbers
orbital diagrams A pictorial representation of electron configurations is an orbital diagram. The following is an orbital diagram.
The electron removed during ionization will always be a(n): Select the correct answer below: outermost electron core electron 1s electron 3d electron
outermost electron Whichever electron resides in the highest energy orbital, which must be the outermost valence electron, that is the one that will be removed first.
Use the figure provided to determine which of the following describes NH3. Select the correct answer below: nonpolar covalent ionic polar covalent none of the above
polar covalent .............. NH3 is polar covalent (0.9).
Bond dissociation energies are always: Select the correct answer below: positive negative zero depends on the molecule
positive ........... It will always require energy to break a bond, so bond dissociation energies are always positive.
Once all of the valence electrons have been placed on a Lewis structure: Select the correct answer below: -add electrons to satisfy the octet rule -remove electrons to satisfy the octet rule -rearrange electrons to satisfy the octet rule -none of the above
rearrange electrons to satisfy the octet rule If there are atoms without a full octet, we can move lone pairs and covalent bonds around in an effort to fill those octets.
Ionization energy refers to the energy required to: Select the correct answer below: remove an electron from an atom in the gaseous state remove an electron from an atom in the solid state add an electron to an atom in the gaseous state add an electron to an atom in the solid state
remove an electron from an atom in the gaseous state Ionization energy specifically refers to the removal of electrons, or the generation of cations, and these atoms must be in the gas state.
For elements in the s block, the first electron removed will be a(n): Select the correct answer below: s electron p electron d electron f electron
s electron .... Elements in the s block will lose s electrons first.
For elements in the d block, the first electron removed will be a(n): Select the correct answer below: s electron p electron d electron f electron
s electron ...... Even though d electrons were the last to be added for an element in the d block, and the d orbitals are slightly higher in energy than the s orbital immediately preceding, these elements will lose their outermost s electrons first.
When drawing Lewis structures, which atoms must receive lone pairs first? Select the correct answer below: -central atom -terminal atoms -most massive atom -least electronegative atom
terminal atoms We will put lone pairs on the atoms at the edges of the molecule first.
The order in which orbitals are listed on an orbital diagram follows: Select the correct answer below: Hund's rule the Aufbau principle the Pauli exclusion principle the Heisenberg uncertainty principle
the Aufbau principle Orbitals are filled according to Hund's rule and they contain electrons possessing quantum numbers dictated by the Pauli exclusion principle, but the order in which they are listed follows the Aufbau principle.
Which of the following results in a decrease in Zeff, given that the number of protons remains the same? Select the correct answer below: the fluctuation of electrons in the valence shell the removal of electrons from the valence shell the addition of one or more electrons to the valence shell all of the above
the addition of one or more electrons to the valence shell Zeff is the effective nuclear charge, the charge that leads to the Coulomb force exerted by the nucleus on an electron, calculated as the nuclear charge minus shielding. The addition of one or more electrons to the valence shell with the same number of protons present leads to a decrease in Zeff.
The more strongly an atom attracts the electrons in a covalent bond: Select the correct answer below: the greater its electronegativity the lesser its electronegativity the greater its covalent radius none of the above
the greater its electronegativity ................ Electronegativity is a measure of how well an atom attracts the electrons in a covalent bond.
The central atom in a Lewis structure will tend to be: Select the correct answer below: the most electronegative the least electronegative the largest atom the smallest atom
the least electronegative The central atom will be the most metallic, or the least electronegative atom.
We can predict the number of bonds an atom can form from: Select the correct answer below: -the number of core electrons needed to form an octet -the number of electrons needed to form an octet -the size of the valence electrons -all of the above
the number of electrons needed to form an octet We can predict the number of bonds an atom can form from the number of electrons needed to form an octet.
What determines the difference in size of atoms or ions if they are isoelectronic? Select the correct answer below: the number of orbitals the number of neutrons the number of electrons the number of protons
the number of protons The number of protons determines the size of atoms or ions that are isoelectronic. Among a group of isoelectonic species, the one with the least number of protons will be largest, and the one with the most will be smallest.
The change in enthalpy for a reaction can be given by calculating: Select the correct answer below: -the sum of the bond dissociation energies of the products minus the sum of the bond dissociation energies of the reactants -the sum of the bond dissociation energies of the products plus the sum of the bond dissociation energies of the reactants -the sum of the bond dissociation energies of the reactants minus the sum of the bond dissociation energies of the products -none of the above
the sum of the bond dissociation energies of the reactants minus the sum of the bond dissociation energies of the products .............. It will be bonds broken minus bonds formed, so the bond dissociation energies of the reactants minus the bond dissociation energies of the products.
What is true about the covalent bonds in the nitrite ion, NO2^ - ? Select the correct answer below: -they are of equal length -they are of different length -they are of different strength -none of the above
they are of equal length Even though each resonance structure shows one single bond and one double bond, these are actually of the same length in the actual molecule.
Noble gases do not receive electronegativity values because: Select the correct answer below: they are too difficult to measure they are gases they do not form covalent bonds none of the above
they do not form covalent bonds .............. Since electronegativity has to do with covalent bonds, atoms that do not make bonds will not have electronegativity values.
Which type of covalent bond is the strongest? Select the correct answer below: single double triple these are all the same strength
triple ....... The greater the number of electron pairs that are in a bond, the stronger it will be, so the triple bond is the strongest.
Electronegativity increases _________ on the periodic table. Select the correct answer below: up and left up and right down and left down and right
up and right ........... Electronegativity will parallel ionization energy.
In a neutral molecule, the sum of the formal charges on the atoms must be: Select the correct answer below: zero positive negative depends on the molecule
zero If the molecule is neutral overall, any existing formal charges must precisely cancel one another out.
