chemistry

What types of elements form an ionic bond?

A metal and a non-metal.

How is an ionic bond formed in terms of electrons?

Electrons are transferred from the metal atom to the non-metal atom to form full outer shells.

What holds an ionic compound together?

Strong electrostatic forces of attraction between oppositely charged ions in all directions (a giant ionic lattice).

Why do ionic compounds have high melting points?

Ionic compounds have high melting points due to the strong electrostatic forces of attraction between the ions in the giant ionic lattice, which require a large amount of energy to overcome.

When can ionic compounds conduct electricity, and why?

Ionic compounds can conduct electricity when melted or dissolved in water, as the ions are free to move and carry an electric current.

What is the structure of a metallic bond?

A giant lattice of positive metal ions surrounded by a sea of delocalised electrons.

Why do metals conduct electricity and heat?

The delocalised electrons are free to move throughout the structure and carry charge/thermal energy.

Why are pure metals malleable (easy to bend/shape)?

The metal ions are arranged in neat layers that can slide over each other.

What is a covalent bond?

A shared pair of electrons between non-metal atoms.

Why do simple molecular substances have low boiling points?

They have weak intermolecular forces between molecules that require very little energy to overcome.

Why do simple molecular substances NOT conduct electricity?

They have no overall electric charge and no delocalised electrons or free ions to carry charge.

Name three main giant covalent structures you need to know

1. Diamond

2. Graphite

3. Silicon Dioxide ({SiO}2)

Why is Diamond extremely hard and has a high melting point?

Each carbon atom forms 4 strong covalent bonds in a rigid 3D lattice, requiring huge amounts of energy to break.

Why does Graphite conduct electricity?

Each carbon atom only forms 3 bonds, leaving 1 delocalised electron per carbon atom that is free to move throughout the layers.

Why is Graphite soft and slippery?

Carbon atoms form layers with weak forces between the layers, allowing them to slide over each other.

Describe the structure of Silicon Dioxide (SiO}2)

A giant 3D covalent lattice where every silicon atom is bonded to 4 oxygen atoms, and every oxygen atom is bonded to 2 silicon atoms.

Does Silicon Dioxide conduct electricity? Why or why not?

No, because it has no delocalised electrons or free-moving ions. All outer electrons are locked in covalent bonds.