Types Of Substances

Question 1

1.32) All matter is composed of __________ which are bonded together by either __________, ______________ or ______________ bonds.

Answer 1

1) atoms
2) ionic
3) covalent
4) metallic

Question 2

1.32) What 4 main categories can elements and compounds be classified as?

Answer 2

Elements and compounds can be classified into 4 main categories which are: 
   •ionic 
   • simple molecular (covalent) 
   • giant covalent 
   • metallic

Question 3

1.32/1.33) Describe the bonding and structure of ionic compounds and how these affect the properties of an ionic compound.

Answer 3

BONDING: Ionic compounds consist of a metal bonded to a non-metal via electron transfer and they form a giant ionic lattice structure where oppositely charged ions are regularly arranged and held together by strong electrostatic forces known as ionic bonds.

PROPERTIES:
• High melting and boiling points - this is due to the strong bonds between each ion that need a lot of energy to be overcome. This is also why ionic compounds are solid at room temp and non-volatile
• Usually soluble in water
• Ionic compounds can conduct electricity in the molten state or in solution as they have ions that can move/flow and carry charge.
• However, they cannot conduct electricity in the solid state as there are no free ions to move.

Question 4

1.32/1.34) Describe the bonding and structure of simple covalent molecules and how these affect the properties of the simple covalent molecules

Answer 4

BONDING: Small covalent compounds consist of non-metal elements which have been bonded together via electron sharing.

PROPERTIES:
•Low melting and boiling points - this is due to the weak intermolecular forces between each molecule being easily overcome. This means that they are usually liquids or gases at room temp and are usually volatile.
•Some are soluble in water and some aren’t
•They cannot conduct electricity as all the electrons are involved in bonding so there are no free electrons or ions to carry charge.

Question 5

Explain the bonding in giant covalent structures.

Answer 5

Giant covalent structures consist of many non-metal atoms bonded to other non-metal atoms via strong covalent strong covalent bonds

Question 6

1.35) What are allotropes?

Answer 6

Different structural forms of a particular element, for example the allotropes of carbon.

Question 7

1.35) Graphite and diamond are…..

Answer 7

allotropes of carbon (different structural forms of carbon) and are examples of giant covalent structures.

Question 8

1.36) Describe the structure of diamond and its properties.

Answer 8

In diamond, each carbon atom bonds with 4 other carbon atoms with strong covalent bonds, forming a tetrahedron.

Diamond has the following properties:
• High melting and boiling point - this is due to the strong covalent bonds that require a lot of energy to be overcome
•Doesn’t conduct electricity - this is due to all the outer shell electrons in carbon being used in bonds, so there are no freely moving charged particles to carry charge
• Hard

Question 9

1.36) Describe the structure of graphite and its properties.

Answer 9

In graphite, each carbon atom is bonded to 3 other carbon atoms with strong covalent bonds forming layers of hexagons leaving one free electron per carbon atom. There are weak intermolecular forces between each layer.

Graphite’s properties include:
•High melting and boiling points - this is due to the strong covalent bonds that require a lot of energy to be overcome
• Conducts heat and electricity - this is due to delocalised electrons that are free to move and carry charge
•Soft and slippery - due to weak intermolecular forces between each layer meaning the layers can slide over each other.

Question 10

1.37) Why is graphite used to make electrodes and to be used as a lubricant?

Answer 10

This is because graphite is soft and slippery, this property is due to the weak intermolecular forces between each layer allowing them to slide over each other making them useful as lubricants and as pencil lead. They are used to make electrodes as graphite can conduct electricity this is due to delocalised electrons being able to move and carry charge.

Question 11

1.37) Why is diamond used in cutting tools?

Answer 11

This is because diamond is hard due to the very strong covalent bonds between each carbon atom.

Question 12

1.38) What are fullerenes?

Answer 12

Fullerenes are a group of carbon allotropes which consist of molecules that form hollow tubes or spheres.

Question 13

1.38) Describe the bonding and properties of fullerenes like C60 (buckminsterfullerene).

Answer 13

Fullerenes are made up of carbon atoms arranged in hexagons/pentagons/heptagons forming hollow balls or tubes.
–> C60 has each carbon atom covalently bonded to 3 other carbon atoms forming 20 hexagons and 12 pentagons which form a hollow sphere.

PROPERTIES:
• Huge surface area - making them useful as industrial catalysts
• Can be used to trap other molecules by forming around the target molecule and capturing it making them useful for targeted drug delivery systems.
•Some can be used as lubricants

Question 14

1.38) What is graphene?

Answer 14

One sheet of graphite and allotrope of carbon.

Question 15

1.38) Describe the bonding and properties of graphene