Chem Exam Two Chem 101
What is the formula for percent composition:
(Molar mass of element * amt of element in compound)/ molar mass of whole molecule
What is the formula for bond order:
(bonding electrons - antibonding electrons)/2
Allowed values of ms are:
+1⁄2, -1⁄2
Allowed values of ml is
-l...0...l
How many electrons in an atom can have the following quantum numbers? n = 8, ℓ = 2, mℓ = -2, ms = +½
1
What is the energy, in J, of light that must be absorbed by a hydrogen atom to transition an electron from n = 3 to n = 5? Submit an answer to three significant figures.
1.549 x 10^-19 J
Write the complete ground state electron configuration for Cr
1s22s22p63s23p64s13d5
What is the electron configuration for the barium atom?
1s22s22p63s23p64s23d104p65s24d105p66s2 or [Xe] 6s2
Write the electron configuration for Cu2+
1s22s22p63s23p64s23d7 or [Ar] 4s23d7
Write the electron configuration for Zn2+
1s22s22p63s23p64s23d8 or [Ar] 4s23d8
What is the electron configuration of Co²⁺?
1s²2s²2p⁶3s²3p⁶3d⁷
The ground state electron configuration of a Se atom is
1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁴
Which of the following electron configurations represent a transition metal atom?
1s²2s²2p⁶3s²3p⁶4s²3d⁷
How many electrons are being shared between two atoms with a single bond? Double bond? Triple bond?
2, 4, 6
What is the wavelength of light (in nm) emitted when an electron transitions from n = 4 to n = 2 in a hydrogen atom? Submit an answer to three significant figures.
486 nm
Of the following, which sublevel is filled last?
4d
Which of the orbital electron configurations is not possible?
4p⁷
How many electrons in an atom can have the quantum numbers n = 3, l = 1?
6 electrons → ml can be -1, 0, or 1 and each can have a spin (ms) of +1⁄2 or -1⁄2 (3*2=6)
Predict the chemical formula for the ionic compound formed by the elements Ag and N
Ag₃N
What is the formula for aluminum chloride
AlCl3
__________ describes the shape of the orbital
Angular Momentum Quantum Number (l)
What atoms can have more than 8 electrons?
Atoms on row 3 and below
Based on their positions in the periodic table, which of the following bonds is the most polar? a. O-F b. C-F c. B-F d. F-F
B-F
Write the compound between C and O and state if ionic or covalent
CO2 covalent
What is the formula for chlorine dioxide
ClO2
Write the chemical formula for chromium(VI) sulfate
Cr(SO₄)₃
Write the chemical formula for copper(I) hydroxide
CuOH
The equation to determine the energy of a photon is
E = h*v
_________ describes the spin of electrons in the atomic orbital
Electron Spin Quantum Number (ms)
What is Aufbau's principle?
Electrons are added to the lowest energy orbitals first
The formula of europium oxide is Eu₂O₃. Based on this information, what is the formula of the compound made from europium and chloride ions?
EuCl₃
What element is designated by the orbital diagram below? 2s 2p 1s
F
Which atom in the Br-F molecule has a partial negative charge (δ⁻)? a. F b. Br c. Both d. Neither
F
Which of the following bonds is a nonpolar covalent bond?
F - F
Write the compound between Fe and O and state if ionic or covalent
FeO or Fe2O3 ionic
Predict the chemical formula for the ionic compound formed by Fe³⁺ and O²⁻
Fe₂O₃
What is the most electronegative atom?
Fluorine (F)
What is the formula for formal charge?
Formal charge = V(valence electrons) - lone pairs - (bonding electrons/2)
What quantum mechanics principle states that electrons are added to atomic orbitals with the same energy so that each orbital is singularly occupied with electrons having the same spin?
Hund's Rule
What atoms can have less than 8 electrons?
Hydrogen, Boron, Beryllium
Classify the following compounds as ionic or covalent: KCl, CrCl₃, Cl₂O.
Ionic, ionic, covalent.
Which of the following compounds exhibits both ionic and covalent bonding?
KNO₃
What is the noble gas core in the electron configuration for Ru?
Kr
What is the formula for lithium sulfate
Li2SO4
_________ describes the orientation of orbital in space
Magnetic Quantum Number (ml)
What is the formula for magnesium acetate
Mg(CH3COO)2
Which of the following electron configurations is incorrect?
Mn [Ar]4s²4d⁵
What is the formula for sodium nitrate
NaNO3
What is the Pauli Exclusion Principle?
No two electrons in an atom can have the same quantum numbers
Which element has the electron configuration: 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f5
Np
Which following ions has the same electron configuration as a noble gas?
N³⁻
Which of the following ions has the electron configuration 1s²2s²2p⁶?
N³⁻
What can be used to determine empirical formula?
Percent composition and molecular formula
________ corresponds to the number of shells in the Bohr model and designates size of orbital
Principle Quantum Number (n)
What is Hund's rule?
Put 1 electron in each degenerate orbital before pairing electrons
Write the chemical formula for diphosphorus pentabromide
P₂Br₅
Write the chemical formula for tetraphosphorus hexasulfide
P₄S₆
List the 4 steps to solve for empirical formula based of percent composition
Step 1 → assume you have 100g of each element (ex: 79.23% of C is 79.23 g of C) Step 2 → how many moles of each element are there (convert grams to moles using molar mass) Step 3 → divide each moles of elements by the lowest number of moles you calculated (ex: 2.17 moles of N and 4.35 moles of O → 2.17/2.17 = 1 and 4.13/2.17 = 2) Step 4 → solve for empirical formula with whole numbers found
What is resonance?
Two or more structures that differ only by the placement of electrons
Delocalization of electrons occur when?
When there are pi bonds and resonance structures
Can bond order be fractional and if so when?
When there are resonance structures
Write the abbreviated ground state electron configuration for Kr
[Ar] 4s23d104p6
Write the electron configuration for Br-
[Ar] 4s23d104p6 or 1s22s22p63s23p64s23d104p6
What is the electron configuration of the element with atomic number 113?
[Rn] 7s25f146d107p1
Based on the positions of the following elements on the periodic table, which of them would you expect to form a 3+ cation? a. scandium b. aluminum c. phosphorus d. calcium e. a & b
a & b
Which of the following combinations of quantum numbers is not allowed? (Combinations are listed as follows: n, l, m(l), m(s).) a. 1,1,0,-1⁄2 b. 3,0,0,-1⁄2 c. 3,1,1,1⁄2 d. 5,3,1,-1⁄2 e. 3,2,0,1⁄2
a. 1,1,0,-1⁄2
What is the correct IUPAC name for AlBr₃?
aluminum bromide
The height of the crest or depth of the trough is the
amplitude
Name CO and state whether ionic or covalent
carbon monoxide; covalent
What is the correct IUPAC name for Cr₂O₃?
chromium(III) oxide
What is the correct IUPAC name for CoCl₂
cobalt(II) chloride
(ionic/covalent) bonds share electrons
covalent
A bond formed between 2 nonmetals with a small difference in electronegativity is a(n) (ionic/covalent) bond
covalent
is PI3 a covalent or ionic bond? If covalent is it polar or nonpolar
covalent polar due to presence of lone pair
Is NO2 a covalent or ionic bond? If covalent is it polar or nonpolar
covalent nonpolar due to presence of lone pair
Waves out of phase (increase/decrease) overall bonding
decrease
As bond length increases bond strength (decreases/increases)
decreases
As bond order increases bond length (decreases/increases)
decreases
As frequency increases, wavelength
decreases
Going down the periodic table electronegativity
decreases
Going left to right across the periodic table bond length (increases/decreases)
decreases
Increasing bond order (increases/decreases) bond length
decreases
aas energy increases wavelength
decreases
Atoms or molecules having all paired electrons are
diamagnetic
When all of the electrons in an atom are paired the atom is called
diamagnetic
What is the correct IUPAC name for N₂O₄?
dinitrogen tetroxide
_______ describes the ratio of each atom in a molecule to the lowest number
empirical formula
What happens to the energy of a photon if the wavelength is doubled?
energy is reduced by one-half
number of times a wave passes through a point
frequency
Which of the following forms of radiation has the highest frequency?
gamma rays
In the Bohr model of the hydrogen atom, the energy required to excite an electron from n = 2 to n = 3 is _______________ the energy required to excite an electron from n = 3 to n = 4?
greater than
Name B6Si and state whether ionic or covalent
hexaboron silicide; covalent
Higher bond order (higher/lower) stability
higher
Waves in phase (increase/decrease) overall bonding
increase
As bond order increases bond strength (decreases/increases)
increases
As energy increases, frequency...
increases
Going down the periodic table bond length (increases/decreases)
increases
Going left to right across the periodic table electronegativity
increases
(ionic/covalent) bonds transfer electrons
ionic
A bond formed between a metal and a nonmetal with a large difference in electronegativity is a(n) (ionic/covalent) bond
ionic
Is AlF3 a covalent or ionic bond?
ionic
Name FeBr2 and state whether ionic or covalent
iron (II) bromide; ionic
What is the correct IUPAC name for Fe(NO₂)₂?
iron(II) nitrite
Given a particular value of the principal quantum number (n), which quantum number primarily determines the shape of an orbital?
l
Given n = 2, which of the quantum numbers is NOT possible.
l = 2
To find l use the equation:
l = n-1
The best structure has the (highest/lowest) amount of ion charges
lowest
Consider the following set of quantum numbers: n = 2, l = 1, m(l) = -1, and m(s) = 0. This is NOT a possible set of quantum numbers for an electron in an atom. Choose the incorrect quantum number.
m(s) = 0
To find molecular formula from empirical formula ________ is needed
molar mass of the compound
A single electron in an orbital has quantum numbers n = 2, ℓ = 0, mℓ = 0, ms = +½. What are the quantum numbers for the next electron added to this atom?
n = 2, ℓ = 0, mℓ = 0, ms = -½
Which of the following sets of quantum numbers is not allowed?
n = 4, l = 0, ml = -1
What is the correct IUPAC name for HNO₂(aq)?
nitrous acid
If there are polar bonds in the lewis structure but they are evenly distributed the lewis structure will most likely be (polar/nonpolar)
nonpolar
f there are no lone pairs on the central atom and bonds are nonpolar the lewis structure will most likely be (polar/nonpolar)
nonpolar
Atoms or molecules having unpaired electrons are
paramagnetic
Where there are one or more unpaired electrons the atom is called
paramagnetic
If the central atom has at least one polar bond and the rest are not identical the lewis structure will most likely be (polar/nonpolar)
polar
Which type of electromagnetic radiation has the largest wavelength?
radio waves
What are the values of l for an s, p, d, and f orbital?
s orbital: l = 0 p orbital: l =1 d orbital: l =2 f orbital: l = 3
If light has a lot of energy, it will have:
small wavelength
Name Na2CO3 and state whether ionic or covalent
sodium carbonate; ionic
Name NaOH and state whether ionic or covalent
sodium hydroxide; ionic
In an investigation of the electronic absorption spectrum of a particular element, it is found that a photon having λ = 500 nm provides just enough energy to promote an electron from n = 2 to n = 3. From this information, we can deduce
the difference between the energies of the n= 2 and n= 3 levels
Which group in the periodic table tends to have high electronegativity values?
the halogens
In a covalent bond
two atoms share valence electrons and those shared electrons form the chemical bond.
Which of the following best describes what happens when an ionic bond forms?
two atoms, one atom which is more electronegative than the other, exchange electrons and the charges hold the atoms together.
The equation to determine frequency is
v = c/λ
distance from crest to crest or trough to trough
wavelength
The Rydberg equation for the hydrogen atom is
ΔE = -2.178 x 10-18 J * ((1/n2final) - (1/n2initial)
The equation to determine wavelength is
λ = c/v
