Review for Chemistry Final Exam - Part 1

Exam 1 Content

• 02 Atoms, Molecules and Ions

• 06 Electronic Structure and Periodic Trends

• 07 Basic Concepts of Chemical Bonding

• 08 Molecular Shapes

• 09 Bonding Theory

02 Atoms, Molecules and Ions

The Periodic Table
The Atomic Theory
Looking Inside Atoms

Multiple Select

Nonmetals (select all that apply)

• are found on the right side of the periodic table.

• are found on the left side of the periodic table.

• are good conductors of heat and electricity.

• are brittle.

• can be solid, liquids, or gases at room temperature.

The periodic table organizes elements in rows and columns.
Going from top to bottom and from left to right, elements are arranged in order of atomic number. (Ptable.com)

Multiple Choice

How does hydrogen peroxide (H₂O₂) differ from water (H₂O) in terms of oxygen content?

• It has twice as much oxygen

• It has half as much oxygen

• It has the same amount of oxygen

• It has no oxygen

Dalton's Atomic Theory noted mass conservation, definite proportions, and multiple proportions as evidence for atoms

Multiple Choice

How many neutrons are in the Calcium-42 isotope?

• 20
• 40
• 22
• 42

Multiple Choice

Which has more Electrons the Rubidium cation or Iodide anion?

• Rubidium
• Iodine

Atoms are made of protons, neutrons and electrons.
The mass number is the number of protons plus neutrons.
Atomic charge is the number of protons minus electrons.

06 Electronic Structure and Periodic Trends

Electromagnetic Radiation and Energy in Light
Energy in Atoms
Many-Electron Atoms
Atomic Orbitals and Quantum Numbers
Electron Configurations

Multiple Choice

What is the frequency of a light wave with a wavelength of 400 nm?

(E = h⋅ν; c = λ⋅ν)

(c = 2.9979 x 10^8 m/s; h = 6.626 x 10^-34 J⋅s)

• 3.5 x 10^14 Hz

• 5.0 x 10^14 Hz

• 9.0 x 10^14 Hz

• 7.5 x 10^14 Hz

Electromagnetic Radiation is described as a wave-packet.
It has a frequency, wavelength, and photon energy.
The speed of light, c and Planck's constant, h are important.

Multiple Choice

What value of L would produce an emission of frequency 7.32 x 10¹⁴ Hz if S = 2 ?
R = 1.097 x 10⁷ m^-1

• 3
• 4
• 5
• 6

Multiple Choice

Which electron transition involves the greatest release of energy?

• n=4 to n=1

• n=6 to n=4

• n=1 to n=7

• n=3 to n=1

• n=7 to n=2

Energy in the H atom is described by the Bohr Model.
Energy levels are calculated using the Rydberg Equation.
Energy reduction => emission; Energy increase => absorption

Multiple Choice

"Electrons have particle and wave-like properties."

• Planck
• Heisenberg
• de Broglie
• Schrodinger

Schroedinger's equation is a differential equation that yields approximate energy levels and atomic orbitals for each atom.
Electrons fill atomic orbitals in order of increasing energy.

Multiple Choice

How many p orbitals are there in a sublevel?

• 2
• 1
• 4
• 3

Multiple Choice

How many electrons can each p orbital hold?

• 6
• 3
• 2
• 4

Shells or rows are counted by principal quantum numbers n = 1, 2, 3,...
Subshells or blocks have angular quantum numbers 0(s), 1(P), 2(D), 3(F)
Each atomic orbital holds two electrons, spin 1/2 (up) and -1/2(down)

Multiple Choice

Which is the electron configuration for an oxygen atom?

• 1s²2s²2p⁶3s²3p⁶4s²
• 1s²2s²2p⁴
• 1s²2s²2p⁶
• 1s²2s²2p⁶3s²3p⁶

Multiple Select

Which is a valid electron configuration for an oxide anion O^2-?

• 1s²2s²2p⁶

• 1s²2s²2p⁴
• 1s²2s²2p²

• [Ne]

Multiple Choice

What atom matches this electron configuration?
[Xe] 6s² 4f¹⁴ 5d⁹

• Mercury
• Gold
• Platinum
• Thallium

Electron configurations usually fill atomic orbitals in the order below until all electrons are accounted for, including any ion charges.
Exception: transition metal cations lose s-electrons before d-electrons.

07 Basic Concepts of Chemical Bonding

Ionic and Covalent Bonding
Bond Strength, Bond Length, and Bond Polarity
Lewis Structures
Formal Charges
Resonance Structures

Multiple Choice

The chemical bond between a non-metal and another non-metal will be a ________ bond.

• metal

• ionic

• covalent

• polar

Multiple Choice

Carbon and Oxygen will make a ___________ bond.

• ionic

• covalent

• metallic

Multiple Choice

Why do all bonds form?

• filling the outermost energy level to be stable

• to make all atoms the same

• to make other atoms unstable

• to make all atoms different

Ionic bonds form between oppositely charged ions.
This happens when electrons transfer from a metal to a nonmetal.
Nonmetal atoms share electrons instead and form covalent bonds.

Multiple Choice

Which type of bond is generally the longest: single, double, or triple bond?

• Triple bond

• Double bond

• Single bond

• Quadruple bond

Multiple Choice

Which has the strongest carbon-carbon bond? (Hint: First draw the Lewis structure)

• C₂H₆

• C₂H₄

• C₂H₂

• CH₄

Single, double, and triple covalent bonds are possible in molecules.
Greater bond order (number of bonds) between two neighboring atoms indicates a stronger and shorter connection between them.

Multiple Choice

Calculate the Formal Charge for the Oxygen Labeled 1 

• -1
• +1
• 0
• -2

Multiple Choice

Which of the following Lewis diagrams best represents the bonding in the  N₂O  molecule, considering formal charges?

Polyatomic ions require brackets around the Lewis structure.
The formal charge predicts if atoms in a molecule are charged.
Formal charge = Valence electrons - (# of bonds + lone pair electrons)
Excessive formal charges are typically a sign of a poor Lewis structure!

08 Molecular Shapes

VSEPR Model
Molecular Shapes

Multiple Choice

Choose the correct shape for this molecule:

• linear
• Trigonal pyramidal
• Bent
• Tetrahedral

Multiple Choice

Consider the molecule below.  Determine the molecular geometry at each of the 2 labeled carbons.

• C1 = tetrahedral, C2 = linear
• C1 = trigonal planar, C2 = bent
• C1 = bent, C2 = trigonal planar
• C1 = trigonal planar, C2 = tetrahedral

The VSEPR model predicts basic three-dimensional shapes around central atoms in a molecule, based on the number of electron domains.
The basic shapes maximize the angles between electron domains.

Multiple Choice

Elijah, Anika, and Liam are studying chemistry. They come across a molecule and Elijah says, 'This structure is called...'

• tetrahedral

• Trigonal pyramidal

• Seesaw

• Bent/Angular

Drag and Drop

What is the electronic geometry of XeF₂ molecules? ​

Placeholder

What is the molecular geometry of XeF₂ molecule? ​

Placeholder

Drag these tiles and drop them in the correct blank above

trigonal bipyramid

linear

octahedral

Drag and Drop

There are four​

Placeholder

There are two​

Placeholder

The electron geometry of this compound is ​

Placeholder

The molecular geometry of this compound is ​

Placeholder

Drag these tiles and drop them in the correct blank above

bonding groups.

lone pairs of electrons.

octahedral.

square planar.

trigonal planar.

Lone pairs and bonded atoms on the central atomcount toward the steric number, which determines the basic shape. Thus, the molecular geometry cannot be found by only counting the bonded atoms.

09 Bonding Theory

Valence Bond Theory: Hybrid Orbitals
Valence Bond Theory: Sigma and Pi Bonds
Molecular Orbitals: First Period Diatomics
Molecular Orbitals: Second Period Diatomics
Molecular Orbitals: Electron Delocalization

Multiple Choice

​What hybrid orbital is found in water?

• sp

• sp^2

• sp^3

• sp^3d

• sp^3d^2

​Hybrid orbitals are found on central atoms of molecules.
They create the correct bond angles for that central atom, based on the VSEPR model.

By Christine Morales

​Steric Number	​VSEPR Bond Angle	​Hybrid Orbital
​2	180°​	​sp
3​	120°​​	​sp
4​	​109.47°​	​sp
5​	​90°​, 120°​, 180°​	​sp
6​	​90°​, 180°​	​sp

Multiple Choice

How many sigma and pi bonds does this have?

• 1 sigma and 1 pi
• 2 sigma and 1 pi
• 1 sigma and 2 pi
• 2 sigma and 2 pi

​Sigma bonds form the single-bond skeleton between atoms.
Pi bonds form second or third bonds between two atoms.
In resonance structures, pi-bonding electrons are delocalized.

By Christine Morales

Bond Order	​Sigma Bond Order	Pi Bond Order
​1	1	0
2	1	1
3	1	2
1.33	​1	​0, 0, 1 (resonance)
1.50	1	0, 1 (resonance)

Multiple Select

Which of the following statements is true?

• Electrons are never found in an antibonding MO.

• All antibonding MOs are higher in energy than the atomic orbitals of which they are composed.

• Antibonding MOs have electron density mainly outside the space between the two nuclei.

• None of the statements is true

In molecular orbitals, electrons can be bonding or antibonding.
Two atomic orbitals form one bonding and one antibonding MO.
Electrons from atoms fill MO's from the bottom to the top.

By Christine Morales

Multiple Choice

What is the bond order of He₂⁺?

• 2

• 0

• 1/2

• 1

• 1 1/2

Electrons in bonding and antibonding MO's explain bond orders.

Unpaired electrons in orbitals explain paramagnetism.

Count electrons carefully in polyatomic ions.

By Christine Morales

Multiple Choice

The electron configuration of a particular diatomic species is (σ2s)²(σ*2s)²(σ2p)²(π2p)²(π*2p)⁴. What is the bond order for this species?

• 1.5

• 1

• 0.5

• 0

• 2

Electrons in bonding and antibonding MO's form electron configurations.

Practice recognizing MO symbols.
Use stars to indicate antibonds.

Bond order =
(¹/₂)(Bonding e^-'s - Antibonding e^-'s)

By Christine Morales

CN^-: (σ_1s)²​​(σ*_1s)²(σ_2s)²​(σ*_2s)²(σ_2p)²(π_2p)⁴

Multiple Choice

Butadiene, C4H6, demonstrates electron delocalization.

How do molecular orbitals explain this property?

• They show two C=C pi bonds.

• They show three C-C sigma bonds.

• They show paramagnetism.

• They show a shared C=C-C=C pi bond.