2.5.3: covalent bonding

Question 1

what is a covalent bond?

Answer 1

the sharing of pairs of electrons between two non-metal atoms
e.g. H2, CO2, NH4+

Question 2

why do atoms bond covalently?

Answer 2

because there’s a strong electrostatic attraction between the shared pair of electrons and the nuclei of the atoms
the attraction is localised and acts solely between the shared pair of electrons and nuclei

Question 3

what are lone pairs?

Answer 3

non bonded pairs of outer electrons

Question 4

what is co-ordinate bonding/dative covalency?

Answer 4

where 1 atom contributes both of the shared electrons that was originally a lone pair and another atom/ion with a vacant orbital bonds to it

Question 5

what’s an example of a co-ordinate bond?

Answer 5

ammonium

a H+ ion bonds to the lone pair on a NH3 molecule to form NH3+

Question 6

do covalent bonds conduct electricity?

Answer 6

no because there’s no free electrons

the only exception is graphite

Question 7

describe the melting/boiling point of covalent bonds?

Answer 7

they have a low melting/boiling point because even though the covalent bonds within the molecules are strong the london forces between the molecules are weak so little energy is needed to break the intermolecular forces