Covalent bonding

Question 1

How is a covalent bonding formed?

Answer 1

when atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong

Question 2

where do covalent bondings occur?

Answer 2

it occurs in most non-metallic elements and in compounds of nonmetals

Question 3

what are strong bonds between atoms that are covalently bonded the result of?

Answer 3

electrostatic attraction between the positive nuclei of the atoms and the pairs of negative electrons that are shared between them

Question 4

substances that consist of small molecules are usually gases or liquids that have what?

Answer 4

a low boiling point

Question 5

substances that consist of small molecules have a weak what?

Answer 5

a weak intermolecular forces between the molecules. They are broken in boiling or melting

Question 6

subsbtances that consist of small molecules don’t conduct what?

Answer 6

electricity because small molecules do not have an overall electric charge

Question 7

what do the melting and boiling point of substances with simple molecular structures increase with?

Answer 7

with increasing relative molecular mass

Question 8

what are substances that consist of giant covalent structures?

Answer 8

they are solids with very high melting points

Question 9

what are all atoms with giant covalent structures and high melting points linked to?

Answer 9

they are linked to other atoms by strong covalent bonds

Question 10

how does the structure of a diamond increase its physical property, electrical conductivity and hardness?

Answer 10

• in a diamond each carbon is joined to 4 carbons covalently.
• it’s very hard, has a very high melting point and does not conduct electricity

Question 11

how does the structure of a graphite increase its physical property, electrical conductivity and hardness?

Answer 11

• in a graphite, each carbon is covalently bonded to 3 other carbons, forming layers of hexagonal rings, which have no covalent bonds between the layers
• the layers can slide over each other due to no covalent bonds, meaning graphite is soft and slippery
• one electron from each carbon atom is delocalised, making graphites similar to metals and can conduct electricity

Question 12

what is a graphene?

Answer 12

• single layers of graphite

- has properties that make it useful in electronics and composites

Question 13

what are carbon nanotubes?

Answer 13

• cylindrical fullerenes with very high length to diameter ratios
• their properties make them useful for nanotechnology