Covalent bonding

molecule

uncharged group of two or more atoms held together

Covalent bonds are formed when

atoms share a pair of electrons

properties substances made of molecules…(2)

have low melting and boiling points

don’t conduct electricity

The length of a single covalent bond is related to the…(2)

size of the atoms

the distance between the nucleus and outer shell of electrons for each atom

The length of a double bond between two atoms is...

shorter than a single bond between the same atoms

longer than a triple bond between the same atoms

Predict which bond is longer.

C≡N

C≡C

Carbon is larger than nitrogen, so a C≡C bond should be longer than a C≡N bond.

Why is carbon larger than Nitrogen ?

Both nitrogen and carbon’s outer electrons are in the second shell.

Nitrogen has a larger nuclear charge, so its outer electrons are held closer (on average) to the nucleus.

The strength of a single covalent bond is related to…(2)

the length of the bond

the size of the atoms involved

trend in the strength of double, single and triple bond?

single<double<triple

provided between the same atom

Predict, based on bond lengths, which bond is stronger.

H-S

H-O

Oxygen atoms are smaller than sulfur atoms

This means an H-O bond should be shorter than an H-S bond.

And this means that an H-O bond should be stronger than an H-S bond

A dative bond forms when…

one atom contributes both electrons to the shared pair

In “bonds as sticks” diagrams we represent dative bonds as…

an arrow

Forming a dative covalent bond requires…

a dative bond donor

a dative bond acceptor

What is the correct representation for a dative bond from phosphorus to hydrogen?

D