Worksheet: Molecular Orbital Diagrams of Diatomics

In this worksheet, we will practice comparing the energies and arrangement of molecular orbitals in diatomics and identifying the effects of s–p mixing.

Q1:

Which of the following is a consequence of s-p mixing?

  • AThe second ionization of N2 produces a diamagnetic ion.
  • BThe first ionization of N2 produces a paramagnetic ion.
  • CThe second ionization of O2 produces a diamagnetic ion.
  • DThe fourth ionization of O2 produces a paramagnetic ion.
  • EThe first ionization of C2 produces a paramagnetic ion.

Q2:

Which of the following statements is true?

  • AThe F2+2 ion has a bond order of 2.
  • BIt is not possible for the orbitals in a subshell to form molecular orbitals if the subshell is empty.
  • CThe effect of s-p mixing increases with atomic number across a period.
  • DThe F2+2 ion is diamagnetic.
  • EThe order of the 𝜎p and 𝜋p orbitals in a Cl2 molecule is reversed due to s-p mixing.

Q3:

In which of the following molecules is the 𝜎s orbital lowest in energy?

  • A B 2
  • B N 2
  • C C 2
  • D F 2
  • E O 2

Q4:

Which of the following molecules and ions is diamagnetic?

  • A B 2
  • B C 2 2
  • C O 2 +
  • D F 2
  • E O 2

Q5:

For which of these elements does the formation of a neutral homonuclear diatomic molecule decrease the first ionization energy?

  • A H
  • B O
  • C C
  • D N
  • E B

Q6:

In which of these molecules does the first ionization result in the removal of a 𝜎 electron?

  • A C 2
  • B N 2
  • C F 2
  • D O 2
  • E B 2

Q7:

Which of the following ions has the highest bond order?

  • A N 2 2
  • B B 2 2
  • C B e 2 2
  • D L i 2 2
  • E C 2 2

Q8:

Which of the following ions has the highest bond order?

  • A S 2 2 +
  • B P 2 2 +
  • C A l 2 2 +
  • D N a 2 2 +
  • E A r 2 2 +

Q9:

What is the bond order of Be2+?

Q10:

What is the bond order of O22?

  • A1
  • B1.5
  • C0
  • D2
  • E0.5

Q11:

In the MO diagram of a heteronuclear diatomic molecule, which of the following is an accurate description of the relative energies of the atomic orbitals?

  • AThe atomic orbitals are drawn at the same energy to indicate bond formation.
  • BThe orbital of the atom with the highest electronegativity is drawn at the lowest energy.
  • CThe orbital of the atom with the highest number of electron lone pairs is drawn at the lowest energy.
  • DThe orbital of the atom with the smallest radius is drawn at the lowest energy.
  • EThe atomic orbitals are drawn at the same energy to indicate allowed symmetry.

Q12:

H 2 and He2 both have completely filled bonding molecular orbitals. Why does helium gas consist of separate atoms while hydrogen gas is diatomic?

  • A H e 2 also has electrons in antibonding orbitals, resulting in a bond order of zero.
  • BHelium is a noble gas and never forms bonds.
  • C H e 2 also has electrons in nonbonding orbitals, resulting in a bond order of zero.
  • D H 2 has no antibonding orbitals, resulting in a bond order of two.
  • E H 2 also has electrons in nonbonding orbitals, resulting in a bond order of two.

Q13:

Calculate, to 1 decimal place, the bond order of the diatomic ion with the electronic configuration: (𝜎)(𝜎)𝜋,𝜋𝜋,𝜋.

Q14:

Calculate, to 1 decimal place, the bond order of a diatomic molecule with the electronic configuration (𝜎)(𝜎)𝜎𝜋,𝜋.

Q15:

Calculate, to 1 decimal place, the bond order of the diatomic ion with the electronic configuration (𝜎)(𝜎)𝜋,𝜋𝜎𝜋,𝜋sspypzpxpypz.

Q16:

What is the bond order for the Be2 molecule?

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