Covalent Bonding

Question 1

Define covalent bonding.

Answer 1

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

Question 2

What does covalent bonding occur between?

Answer 2

Non-metallic elements
Compounds of non-metallic elements
Polyatomic ions

Question 3

What is the key feature of covalent bonding?

Answer 3

The sharing of a pair of electrons between two atoms.

Question 4

In what three ways are the atoms in a covalent bond bonded together?

Answer 4

In a small molecule
A giant covalent structure
A charged polyatomic ion

Question 5

What is a covalent bond the overlap of?

Answer 5

It is the overlap of atomic orbitals.

Question 6

What is the shared pair of electrons attracted to?

Answer 6

The nucleus of both the bonding atoms.

Question 7

What type of electron structure do the outer shells of the bonded atoms have?

Answer 7

The bonded atoms often have outer shells with the same electron structure as the nearest noble gas.

Question 8

What is the attraction like in covalent bonds?

Answer 8

It is localised.

Question 9

What is meant by a localised bond?

Answer 9

This is an attraction at acts solely between the shared pair of electrons and the nuclei of the two bonded atoms.

Question 10

What is a result of localised attraction?

Answer 10

A molecule.

Question 11

What is a molecule?

Answer 11

This is the smallest part of a covalent compound that can exist whilst retaining the chemical properties of the compound.

Question 12

What is the difference between ionic and covalent bonding?

Answer 12

In covalent bonding electrons are shared.

In ionic bonding electrons are transferred.

Question 13

What is a displayed formula?

Answer 13

This is a formula that shows the relative position of atoms and the bonds between them.

Question 14

What do the lines in displayed formulae represent?

Answer 14

Bonds

Question 15

How are lone pairs presented in displayed formulae?

Answer 15

As dots (..).

Question 16

What is a lone pair?

Answer 16

These are any pairs of electrons that are not shared.

Question 17

Which molecule shows that predictions for bonding cannot be based solely on the noble gas electron structure?

Answer 17

BF3

Question 18

What is expansion of the octet?

Answer 18

This is where the outer shell electron configuration is different to that of the nearest noble gas because more electrons are in the outer shell.

Question 19

From which shell is expansion of the octet possible?

Answer 19

N=3

Question 20

When can multiple covalent bonds exist?

Answer 20

When two atoms share more than one pair of electrons.

Question 21

What is the electrostatic attraction between in a double bond?

Answer 21

It is between two shared pairs of electrons and the nuclei of the bonding atoms.

Question 22

What is the electrostatic attraction between in a triple covalent bond?

Answer 22

The electrostatic attraction is between the three shared pairs of electrons and the nuclei of the bonding atoms.

Question 23

What is a dative covalent bond?

Answer 23

This is a bond in which the shared pair of electrons has been supplied by one of the bonding atoms only.

Question 24

What is another word for a dative covalent bond?

Answer 24

Coordinate bond.

Question 25

In a dot and cross diagram, what is used to show a dative covalent bond?

Answer 25

An arrow

Question 26

In which direction does the arrow showing the dative covalent bond point?

Answer 26

It points towards the atom that didn’t share electrons.

Question 27

What is meant by the term average bond enthalpy?

Answer 27

This is a measurement of covalent bond strength.

Question 28

What happens as the average bond enthalpy increases?

Answer 28

The covalent bond gets stronger.