Metallic Bonding and Properties of Materials

Question 1

How do metal elements exist?

Answer 1

Metal elements exist as giant metallic lattice structures

Question 2

Explain metallic bonding

Answer 2

The outermost shell of electrons of a metal atom is delocalised, the electrons are free to move about the metal - this leaves a positive metal ion. The positive metal ions are attracted to the delocalised negative electrons. They form lattice of closely packed positive ions in a sea of delocalised electrons

Question 3

Why does metals have high melting points?

Answer 3

Metals have high melting points because of the strong electrostatic forces of attraction between the positive metal ions and the sea of delocalised electrons

Question 4

What effect does the number of delocalised electrons per atom have on the melting point?

Answer 4

The more delocalised electrons there are per atom, the stronger the bonding will be and the higher the melting point

Question 5

Why are metals good thermal conductors?

Answer 5

The delocalised electrons can pass kinetic energy to each other, making metals good thermal conductors

Question 6

Why are metals good electrical conductors?

Answer 6

Metals are good electrical conductors because the delocalised electrons can move and carry a charge

Question 7

Are metals soluble?

Answer 7

Metals are insoluble because of the strength of the metallic bonds

Question 8

Explain the properties of a solid

Answer 8

A typical solid has particles very close together. This give it a high density and makes it incompressible. The particles vibrate around a fixed point and can’t move about freely

Question 9

Explain the properties of a liquid

Answer 9

A typical liquid has a similar density to a solid and is virtually incompressible. The particles move about freely and randomly within the liquid, allowing it to flow

Question 10

Explain the properties of a gas

Answer 10

In gases, the particles have a lot of energy and are very far apart. The density is pretty low and they are very compressible. The particles move about freely, with not a lot of attraction between them, so they’ll diffuse quickly to fill a container

Question 11

How do you change from a solid to a liquid, or a liquid to a gas?

Answer 11

You need to break the forces that are holding the particles together. To do this you need to give the particles more energy

Question 12

Why do simple covalent compounds have low melting points?

Answer 12

To melt or boil a simple covalent compound you only have to overcome the intermolecular forces that hold the molecules together. You don’t need to break the much stronger covalent bonds that hold the atoms together in the molecule

Question 13

Give the properties of ionic substances

Answer 13

1. High melting and boiling points
2. Solid at room temperature
3. Conducts electricity when molten
4. Soluble in water

Question 14

Give the properties of simple covalent substances

Answer 14

1. Low melting and boiling points
2. Usually liquid/gas at room temperature
3. Does not conduct electricity
4. Soluble in water if the molecule is polar enough

Question 15

Give the properties of giant covalent structures

Answer 15

1. High melting and boiling points
2. Solid at room temperature
3. Only graphite conducts electricity
4. Not soluble in water

Question 16

Give the properties of metallic substances

Answer 16

1. High melting and boiling points
2. Solid at room temperature
3. Conducts electricity
4. Not soluble in water