STUDENT SPACE · TOPIC 5

Multiple bonds and larger molecules

Draw the Extended covalent molecules and check their bonding and lone pairs.

The essentials

A double bond contains two shared pairs of electrons. A triple bond contains three shared pairs.
O₂ has a double bond. N₂ has a triple bond. CO₂ has two double bonds.
Ethene is C₂H₄ with a C=C bond. In methanol, CH₃OH, oxygen bonds to carbon and hydrogen and retains two lone pairs.

Try each question before opening its hint or answer. Use paper for calculations and diagrams.

How many bonding electrons are in one C=C double bond?

Need a hint for Question 1?

Each shared pair contains two electrons.

Check Question 1

Four electrons.

Draw the outer-shell dot-and-cross diagram for N₂.

Need a hint for Question 2?

Each nitrogen needs three additional shared electrons for an octet.

Check Question 2

N₂ has three shared pairs between the N atoms and one lone pair on each N.

Draw the displayed formula of CH₃OH and add the lone pairs on O.

Need a hint for Question 3?

Carbon makes four bonds; oxygen makes two and retains two lone pairs.

Check Question 3

Three H atoms bond to C, C bonds to O, and O bonds to H. O has two lone pairs.

Use the matching chapter worksheet. Attempt independently, compare your reasoning with your partner, then bring unresolved questions to your teacher.