Atomic Orbitals and Electron Configurations

1. Which of the following is not a quantum number?

A. n
B. l
C. s
D. m_s
E. m_l

2. Which represents the correct electron configuration for krypton (Kr)?

A. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
B. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 4d¹⁰ 4p⁶
C. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 3p⁶
D. 1s² 2s² 3s² 4s² 2p⁶ 3p⁶
E. None of the above

3. Which atom has the following electron configuration of 1s² 2s² 2p⁶ 3s² 3p² ?

A. C
B. Si
C. Be
D. Mg
E. None of the above

4. What is the correct way to fill four p electrons according to Hund's Rule?

A. p_1, p_2, p₃, then p₁ again
B. 2 electrons in p₁ and 2 electrons in p₂
C. 1 electron each in p_1, p_2, and p₃
D. p orbital can only hold 3 electrons total
E. none of the above

5. According to the Aufbau Principle, electrons should be filled in order of _______.

A. lowest energy to highest energy orbitals
B. highest energy to lowest energy orbitals
C. principle energy level
D. lowest m_l value to highest m_l value
E. none of the above

Notation: Orbital and Lewis Dot

1. The two exceptions to the octet rule are:

A. Carbon and hydrogen
B. Oxygen and carbon
C. Helium and hydrogen
D. Neon and helium
E. None of the above

2. What types of electrons are represented by dots in Lewis dot structures?

A. Excited electrons
B. Electrons in the kernel
C. Valence electrons
D. All of the electrons in an atom
E. None of the above

3. How many additional electrons would iodine (I) need to have a complete octet?

A. Iodine already has a complete octet
B. 1
C. 2
D. 3
E. None of the above

4. Which atom has a complete octet in its ground state configuration?

A. Atoms cannot have complete octets without sharing electrons
B. Ne
C. N
D. Na
E. None of the above

5. How many non-valence electrons are found in the group state nitrogen (N) atom?

A. 2
B. 7
C. 5
D. Nitrogen only has valence electrons
E. None of the above

Bonding: Covalent and Ionic Bonds

1. Ionic bonds are held together by what force?

A. Electronic
B. Electrostatic
C. Charged
D. Neutral
E. None of the above

2. In a covalent bond, electrons are ____.

A. lost or gained
B. always equally shared
C. always unequally shared
D. shared
E. none of the above

3. How is the bond in F₂ different from the bond in KCl?

A. F₂ has a covalent bond while KCl has an ionic
B. Both bonds are the same.
C. F₂ has an ionic bond while KCl has a covalent bond.
D. F₂ has an electrostatic interaction, while KCL has a covalent bond.
E. None of the above

4. Oxygen has 6 valence electrons and is diatomic. How many covalent bonds are there in an O₂ molecule?

A. 0
B. 1
C. 2
D. 3
E. None of the above

5. Ionic bonds are formed between atoms of _______ and ________.

A. metals and non-metals
B. metals and metals
C. non-metals and non-metals
D. halogens and noble gases
E. none of the above

Geometry of Molecules

1. VSEPR stands for:

A. Valence Shell Electro-Pair Repulsion
B. Valence Shell Electro-Pair Regulation
C. Valence Standard Electron Proper Rotation
D. Valence Standard Electro-Pair Repulsion
E. None of the above

2. In a tetrahedral molecule the angle between bonds is close to:

A. 94.5^o
B. 109.5^o
C. 120^o
D. 180^o
E. None of the above

3. What is the geometry of O₃?

A. Linear
B. Bent
C. Trigonal planar
D. Trigonal pyramidal
E. None of the above

4. What is the molecular shape of BI₃?

A. Tetrahedral
B. Trigonal pyramidal
C. Linear
D. Trigonal planar
E. None of the above

5. The geometry of the carbonate ion, CO₃^2- is best described as:

A. Linear
B. Trigonal planar
C. Tetrahedral
D. Bent
E. None of the above

Answers

Atomic Orbitals and Electron Configurations

1. Which of the following is not a quantum number?

C. s

The four quantum number are n, l, m_l, and m_s.

2. Which represents the correct electron configuration for krypton (Kr)?

A. 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶

According to the Aufbau principle the electrons for Kr have to be filled in order of increasing energy. This means that we fill the orbitals in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p.

3. Which atom has the following electron configuration of 1s² 2s² 2p⁶ 3s² 3p² ?

B. Si

Add all of the super-script numbers. This gives you the total electron count of the atom. The number of electrons is equal to the atom number for neutral atoms. In the current problem there are 14 total electrons. The atom with an atomic number of 14 is silicon.

4. What is the correct way to fill four p electrons according to Hund's Rule?

A. p_1, p_2, p₃, then p₁ again

According to Hund's Rule, when filling the p orbital we start with 1 electron in each suborbital and then start pairing the electrons. Four p electrons are places one each in p_1, p_2, and p₃ and the fourth electron is then also put in p₁ creating a pair of electrons.

5. According to the Aufbau Principle, electrons should be filled in order of _______.

A. lowest energy to highest energy orbitals

The Aufbau principle states that we fill electrons in order of increasing orbital energy. This means that orbitals are filled in the following orbital according to the nifty diagrams we made: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, etc.

Notation: Orbital and Lewis Dot

1. The two exceptions to the octet rule are:

C. Helium and hydrogen

Normally atoms like to have 8 valence electrons total to achieve maximum stability according to the octet rule. Hydrogen and helium are exceptions because they only have room for 2 total electrons in their valence shell.

2. What types of electrons are represented by dots in Lewis dot structures?

C. Valence electrons

A Lewis dot structure is a simple way to represent the valence electrons of an atom. These include the electrons located in the outermost s and p orbitals.

3. How many additional electrons would iodine (I) need to have a complete octet?

B. 1

Iodine is located in group 7 and has just 7 valence electrons. Since the octet rule requires 8 electrons, iodine would have to gain 1 more electron.

4. Which atom has a complete octet in its ground state configuration?

B. Ne

Neon (Ne) a noble gas, has 8 valence electrons in its ground state giving it a complete octet. No further electrons are needed.

5. How many non-valence electrons are found in the group state nitrogen (N) atom?

A. 2

Nitrogen has an atomic number of 7, with 2 electrons in the 2s and 3 electrons in the 2p orbitals. If we subtract the five valence electrons from the 7 total electrons we get 2 non-valence electrons in the atom (located in the 1s orbital).

Bonding: Covalent and Ionic Bonds

1. Ionic bonds are held together by what force?

B. Electrostatic

Ionic bonds are held together by electrostatic forces, which are attraction between two atoms of opposite charge.
2. In a covalent bond, electrons are ____.

D. shared

In a covalent bond electrons between two atoms are shared, sometimes equally as in a non-polar covalent bond and sometimes non-equally shared, as in a polar covalent bond.

3. How is the bond in F₂ different from the bond in KCl?

A. F₂ has a covalent bond while KCl has an ionic

F₂ has a covalent bond between the two F atoms while KCl has an ionic bond between the K⁺ and the Cl^-.

4. Oxygen has 6 valence electrons and is diatomic. How many covalent bonds are there in an O₂ molecule?

C. 2

In the O₂ molecule there are two covalent bonds between the two oxygen atoms. Each oxygen atom also has two lone pairs of electrons.

5. Ionic bonds are formed between atoms of _______ and ________.

A. metals and non-metals

Metals and non-metals tend to form ionic bonds, while non-metals and non-metals tend to form covalent bonds.

Geometry of Molecules

1. VSEPR stands for:

A. Valence Shell Electro-Pair Repulsion

VSEPR stands for valence shell electro-pair repulsion. It is a model for how electron pairs minimize their repulsion by arranging in certain geometries.

2. In a tetrahedral molecule the angle between bonds is close to:

B. 109.5^o

In a tetrahedral molecule the angle between bonds is close to 109.5^o. This angle maximizes the distance between electron pairs.

3. What is the geometry of O₃?

B. Bent

The central oxygen atom is in a bent geometry.

4. What is the molecular shape of BI₃?

D. Trigonal planar

After drawing the correct Lewis dot structure you would find the central B atom is connected to three I atoms and has no lone pairs. This makes BI₃ trigonal planar in geometry.

5. The geometry of the carbonate ion, CO₃^2- is best described as:

B. Trigonal planar

After drawing the correct Lewis dot structure you'll find that the geometry of the carbonate ion is trigonal planar.