Covalent Substances

Question 1

What are the properties of simple molecular substances?(4)

Answer 1

1) strong covalent bonds
2) very weak forces of attraction between molecules
3) Low melting and boiling points because of weak into molecular forces
4) mostly gasses or liquids
Don’t conduct electricity as there’s no ions so there is no electrical charge

Question 2

What are giant covalent structures?

Answer 2

Giant covalent structure are macro molecules

Question 3

How are giant covalent structures different to giant ionic structures?

Answer 3

There are no charged ions in giant covalent structures

Question 4

What are the properties of giant covalent structures?

Answer 4

1) All the atoms are bonded to each other by strong covalent bonds
2) they don’t conduct electricity except for graphite when molten
3) there are no charged ions

Question 5

Name the three types of giant covalent examples

Answer 5

Diamond
Graphite
Silicone dioxide

Question 6

Name the properties of diamond.. (3)

Answer 6

1) Each carbon atom forms four covalent bonds in a very rigid giant covalent structure
2) Diamond is the hardest natural substance and is used for drill tips
3) pretty and sparkly

Question 7

Name the properties of graphite…

(3) -bonds
- conduct?
- arrangement

Answer 7

1) Each carbon atom only forms three covalent bonds
2) layers are held together loosely
3) graphite is the only non-metal which is a good conductor of heat and electricity

Question 8

What is the consequence of having three covalent bonds in graphite?

Answer 8

Three covalent bonds create a leers which are free to slide over each other meaning graphite is soft and slippery

Question 9

Why are the layers and graphite how to get the so loosely?

Answer 9

Because they have a week into molecular forces between the layers

Question 10

Why is graphite a good conductor of heat and electricity?

Answer 10

Each carbon atom has one delocalised electrons and it’s these free electrons that conduct heat and electricity

Question 11

Name the properties of silicone dioxide

Answer 11

1) Sometimes called silica which is what Sand is made of

2) each grain of sand is one giant structure of silicone and oxygen

Question 12

Which substances can form simple molecules?

Answer 12

Covalent bonds

Question 13

Explain why bromine has poor electrical conductivity

Answer 13

It doesn’t contain any ions to carry the charge

Question 14

Explain why graphite has good electrical conductivity

Answer 14

Each carbon atom has a delocalised electron that’s able to carry the charge

Question 15

Explain why bromine has such a low melting point compared with silicone dioxide and graphite

Answer 15

All of the atoms in silicone dioxide and in graphite Are held together by strong covalent bonds. In bromine each molecule is held together with a strong covalent bond but the forces between these molecules are weak

Question 16

Explain why oxygen has such a low melting point

Answer 16

Oxygen has weak intermolecular forces between its molecules it doesn’t take much energy to separate the molecules