B₂ has 6 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 4 bonding, 2 antibonding. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
C₂ has 8 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 6 bonding, 2 antibonding. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Each of two atoms brings one 2s and three 2p orbitals. How many molecular orbitals do they make together?Answer: 8. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Show all 49 questions (46 more)
Fill the levels, continued
F₂ has 14 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 8 bonding, 6 antibonding. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
He₂ has 4 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 2 bonding, 2 antibonding. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
How many electrons do the two π2p orbitals hold when both are full?Answer: 4. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
In B₂, C₂ and N₂, in which order do the bonding orbitals made from 2p fill?Answer: The two π2p orbitals first, then σ2p. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
In O₂ and F₂, which of the orbitals made from 2p is lowest in energy?Answer: σ2p. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
N₂ has 10 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 8 bonding, 2 antibonding. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
O₂ has 12 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 8 bonding, 4 antibonding. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
O₂⁻ (O₂ with one electron added) has 13 valence electrons to place. How many end up in bonding orbitals and how many in antibonding orbitals?Answer: 8 bonding, 5 antibonding. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which line is the valence configuration of C₂?Answer: (σ2s)²(σ*2s)²(π2p)⁴. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
Which line is the valence configuration of O₂?Answer: (σ2s)²(σ*2s)²(σ2p)²(π2p)⁴(π*2p)². Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
Which orbital holds the highest-energy electron of B₂?Answer: π2p. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which orbital holds the highest-energy electron of Li₂?Answer: σ2s. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which orbital holds the highest-energy electron of N₂?Answer: σ2p. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which orbital holds the highest-energy electron of N₂⁺ (N₂ with one electron removed)?Answer: σ2p. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which orbital holds the highest-energy electron of O₂⁺ (O₂ with one electron removed)?Answer: π*2p. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Bond order 17
How is bond order worked out from a molecular orbital diagram?Answer: (bonding electrons − antibonding electrons) ÷ 2. Source: LibreTexts Chemistry, general chemistry text map, 9.7 Molecular Orbitals. Read 2026-10-03.
N₂ loses one electron and becomes N₂⁺. What happens to the bond order?Answer: It falls from 3 to 2.5. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
O₂ loses one electron and becomes O₂⁺. What happens to the bond order?Answer: It rises from 2 to 2.5. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
What is the bond order of B₂?Answer: 1. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
What is the bond order of C₂?Answer: 2. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
What is the bond order of F₂?Answer: 1. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
What is the bond order of He₂?Answer: 0. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
What is the bond order of H₂?Answer: 1. Source: LibreTexts Chemistry, general chemistry text map, 9.7 Molecular Orbitals. Read 2026-10-03.
What is the bond order of Li₂?Answer: 1. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
What is the bond order of Ne₂?Answer: 0. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
What is the bond order of N₂?Answer: 3. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
What is the bond order of N₂⁺ (N₂ with one electron removed)?Answer: 2.5. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
What is the bond order of O₂?Answer: 2. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
What is the bond order of O₂⁺ (O₂ with one electron removed)?Answer: 2.5. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
What is the bond order of O₂⁻ (O₂ with one electron added)?Answer: 1.5. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which of these does the diagram predict will not hold together, with a bond order of 0: Li₂, B₂, F₂ or Ne₂?Answer: Ne₂. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
Which of these has the highest bond order: O₂⁻, O₂, O₂⁺ or F₂?Answer: O₂⁺. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Magnetism 14
A strong magnet holds liquid oxygen between its poles. What in the diagram of O₂ explains this?Answer: Two unpaired electrons in the π*2p orbitals. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
How many unpaired electrons does the diagram of B₂ show?Answer: 2. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
How many unpaired electrons does the diagram of C₂ show?Answer: 0. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
How many unpaired electrons does the diagram of N₂ show?Answer: 0. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
How many unpaired electrons does the diagram of O₂ show?Answer: 2. Source: LibreTexts Chemistry, general chemistry text map, 9.8 Second-Row Diatomic Molecules. Read 2026-10-03. The answer is worked out from the filling order given there.
How many unpaired electrons does the diagram of O₂⁺ (O₂ with one electron removed) show?Answer: 1. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Is F₂ paramagnetic or diamagnetic?Answer: Diamagnetic: every electron is paired. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Is H₂ paramagnetic or diamagnetic?Answer: Diamagnetic: every electron is paired. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Is Li₂ paramagnetic or diamagnetic?Answer: Diamagnetic: every electron is paired. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Is N₂⁺ (N₂ with one electron removed) paramagnetic or diamagnetic?Answer: Paramagnetic: one unpaired electron. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Is O₂⁻ (O₂ with one electron added) paramagnetic or diamagnetic?Answer: Paramagnetic: one unpaired electron. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
What makes a molecule paramagnetic?Answer: One or more unpaired electrons. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which of these is diamagnetic: B₂, N₂, O₂ or O₂⁺?Answer: N₂. Source: Filling order, bond order and magnetism as taught in Purdue University, General Chemistry Topic Review: Molecular Orbital Theory. Read 2026-10-03. The answer is worked out from that filling order.
Which of these is paramagnetic: B₂, C₂, N₂ or F₂?Answer: B₂. Source: Wikipedia, Molecular orbital diagram (diatomic MO diagrams). Read 2026-10-03. The answer is worked out from the filling order.
How this list was compiled: Questions, wrong choices and explanations were written for this site. The filling order (σ2s, σ*2s, then π2p before σ2p from Li₂ to N₂ and σ2p before π2p for O₂ and F₂, then π*2p and σ*2p), the bond order rule and the meaning of paramagnetic and diamagnetic follow three texts read 2026-10-03: Purdue University, General Chemistry Topic Review, Molecular Orbital Theory, https://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/mo.html; LibreTexts Chemistry, general chemistry text map, 9.7 Molecular Orbitals and 9.8 Second-Row Diatomic Molecules; and Wikipedia, Molecular orbital diagram and Bond order. Every electron count, bond order and magnetic answer was worked from that filling order and compared with the values those texts print. Licence: own work
How it works
This molecular orbital diagram practice worksheet with answers takes twelve molecules and ions from H₂ to Ne₂: place the valence electrons, work out the bond order, and say whether the result is paramagnetic. Each answer shows its working.
Read the full guide
Fill the levels
Count the valence electrons and fill from the bottom: σ2s, σ*2s, then the orbitals made from 2p. From Li₂ to N₂ the two π2p orbitals fill before σ2p; in O₂ and F₂ σ2p comes first.
Bond order and magnetism
Subtract the antibonding electrons from the bonding ones and halve the result: N₂ comes to 3, O₂ to 2, He₂ to 0. An unpaired electron anywhere makes the molecule paramagnetic.
Print with answers
The sheet on screen is what prints: remove a question, add more up to the whole set, and tick With answer key. The list under the quiz shows each question with its answer.
Electrons enter the two π orbitals one at a time before they pair; B₂ and O₂ get their unpaired electrons that way.
An ion keeps its parent's order: take the top electron off N₂ or O₂, or add one to O₂.
Questions and answers
How do you find bond order from a molecular orbital diagram?
Count the electrons in bonding orbitals, subtract those in antibonding (starred) orbitals, and divide by two. O₂ has 8 bonding and 4 antibonding valence electrons, so its bond order is 2.
Why is O₂ paramagnetic?
Its last two electrons go one each into the two π*2p orbitals and stay unpaired. A molecule with unpaired electrons is drawn into a magnetic field, which is why liquid oxygen stays between the poles of a magnet.
Why is the order of σ2p and π2p different in N₂ and O₂?
From Li₂ to N₂ the 2s and 2p levels are close enough in energy to mix, which pushes σ2p above the π2p pair. In O₂ and F₂ the gap is wider, so σ2p stays below.
Why does He₂ not exist?
Two electrons fill the bonding σ1s orbital and two fill the antibonding σ*1s orbital. They cancel, the bond order is 0, and no chemical bond holds the two atoms together. Ne₂ comes out the same way.
Does this worksheet come with an answer key?
Yes. Each question shows its answer and working as soon as you pick, the list under the quiz gives every answer, and the printed worksheet comes with a key.