3.1 Metallic Bonding

Question 1

Describe metallic bonding

Answer 1

• The bonding in metals can be described by a model. This states that the electrons in the outer shell of the metal atoms are delocalised. There are strong forces of electrostatic attraction between the positive metal ions and the ‘sea’ of shared negative electrons.
• These forces of attraction hold the atoms close together in a regular structure and are known as metallic bonding. Metallic bonding is very strong.

Question 2

Why do metal atoms become positive ions during metallic bonding?

Answer 2

They give up one of their electrons in their outer shell and share them with all the other atoms in the metal. This means that the atoms will all become positive ions because they’ve lost negative electrons.

Question 3

What do alloys contain?

Answer 3

A metal combined with one or more other elements

Question 4

Why are alloys harder?

Answer 4

The combination of different sized atoms disrupts the metal’s regular structure and means that the layers can no longer slide over each other, making the alloy much harder than pure metal.

Question 5

Describe the properties that metals have due to metallic bonding

Answer 5

• The electrostatic forces between the metal ions and the sea of delocalised electrons are very strong, so need lots of energy to be broken. This means that most substances with metallic bonding have very high melting and boiling points, so they’re generally solid at room temperature.
• The delocalised electrons are free to move so can cary and electric charge and thermal (heat) energy through the metal, so metals are good conductors of electricity and heat.
• The layers of atoms in a metal can slide over each other whilst still being held together by the electrons, making metals malleable and ductile - this means that they can be bent, hammered or rolled into flat sheets and drawn into wires.

Question 6

How are metals’ reactivity ordered?

Answer 6

Through the reactivity series

Question 7

What are metals’ reactivity determined by?

Answer 7

How easily they lose electrons and form positive ions

Question 8

Order the metals in the reactivity series from most reactive to least (11)

Answer 8

• Potassium
• Sodium
• Calcium
• Magnesium
• Aluminium
• Zinc
• Iron
• Lead
• Hydrogen
• Copper
• Silver

Question 9

Describe how ionic, covalent and metallic bonding occurs

Answer 9

• Metals can bind to non-metals via ionic bonding, whereby particles with opposite charges are attracted to each other.
• Non-metals can bind to other non-metals via covalent bonding, whereby electrons are shared.
• Metal atoms can bind to other metals using metallic bonding.

Question 10

Why can metals conduct electricity and carry thermal energy?

Answer 10

In metallic bonding, electrons are delocalised from the lattice of metal ions. These electrons can carry charge, and so metal acts as a conductor of electricity. These electrons can also carry thermal energy, meaning metals are good conductors of heat.

Question 11

What is an example of an alloy?

Answer 11

Steel