Ocr As Chemistry - Structure, Bonding And Properties

Front 1

Metal elements exist as...

Back 1

...giant metallic lattice structures.

Front 2

Explain how metallic bonding works.

Back 2

• The electrons in the outermost shell of a metal atom are delocalised - they are free to move around the metal.
• This leaves a positively charged metal cation e.g. Na+, Mg2+, Al3+
• The metal cations are attracted to the delocalised electrons.
• They form a lattice of closely packed cations in a sea of delocalised electrons.

Front 3

What affects the melting point of metals?

Back 3

• The number of delocalised electrons per atom.
• The more there are, the stronger the bonding will be and the higher the melting point.
• Mg2+ has two delocalised electrons per atom, whereas Na+ has one, so Mg2+ will have a higher melting point.
  
  
• The size of the metal ion and the lattice structure also affect the melting point.
• A smaller ionic radius will hold electrons closer to the nuclei, strengthening the bond.

Front 4

What does malleable and ductile mean?

Back 4

• Malleable means being able to be hammered into sheets
• Ductile means being drawn into wire.

Front 5

What makes metals malleable and ductile?

Back 5

There are no bonds holding specific ions together, so the metal ions can slide past each other when a structure is pulled.

Front 6

Why are metals good thermal conductors?

Back 6

The delocalised electrons are able to pass kinetic energy to each other.

Front 7

Why are metals good conductors?

Back 7

The delocalised electrons can move and carry a current.

Front 8

Metals are .........., except .......... metals, because of the ............ of the .......... bonds.

Back 8

1. insoluble

2. liquid

3. strength

4. metallic

Front 9

Simple molecular structures only...

Back 9

...contain a few atoms e.g. oxygen (O2), chlorine (Cl2) and phosphorous (P4).

Front 10

Intermolecular forces in simple molecular strucures are...

Back 10

...weak.

Front 11

Explain why intermolecular forces between simple molecules are weak and what this results in.

Back 11

• More atoms in a molecule mean stronger induced dipole-dipole forces.
• Simple molecules have few atoms, resulting in weaker induced dipole-dipole forces.
  
  
• This results in simple molecules having lower melting and boiling points.

Front 12

What is the biggest molecule in Period 3? Describe its melting and boiling point.

Back 12

• Sulfur (S8).
  
• It has a higher melting and boiling point due to the stronger induced dipole-dipole forces which are due to a large amount of atoms in the molecule.

Front 13

Describe the melting and boiling points of noble gases and explain your answer.

Back 13

• The noble gases have very low melting and boiling points as they exist as individual atoms.
• This results in very weak intermolecular forces (London forces), which results in low melting and boiling point.

Front 14

For metals, boiling points .......... across a period.

Back 14

increase

Front 15

Why does boiling point increase across a period in metals?

Back 15

Metallic bonds get stronger as the ionic radius decreases and the number of delocalised electrons increases.

Front 16

Name two elements with giant covalent lattices.

Back 16

• Carbon
• Silicone

Front 17

Element with giant covalent lattices have strong .......... bonds linking all their atoms together.

A .......... amount of energy is needed to break these bonds.

Back 17

1. covalent

2. energy

Front 18

The elements that form simple molecular structures have .......... .......... forces between their molecules, so they have .......... melting and boiling points.

Back 18

1. weak intermolecular

2. low

Front 19

The noble gases (e.g. neon and argon) have the .......... melting and boiling points in their period, as they are held together by the .......... froces

Back 19

1. lowest

2. weakest

Front 20

Fill out the following table.

Back 20