igcse Chemistry

Sodium Chloride is an example of [blank_start]ionic[blank_end] bonding.

[blank_start]Covalent[blank_end] bonds take place between two [blank_start]non-metals[blank_end]. This happens by atoms sharing pairs of electrons. A [blank_start]covalent[blank_end] bond always has [blank_start]2[blank_end] electrons.

Metallic Bonding occurs with a [blank_start]lattice[blank_end] of metal [blank_start]ions[blank_end] surrounded by a sea of [blank_start]delocalised[blank_end] electrons. The same applies for [blank_start]alloys[blank_end], however there will be at least 2 different types of metal ion in the [blank_start]lattice[blank_end]. Electrons can become [blank_start]delocalised[blank_end] easily because metals have [blank_start]few[blank_end] electrons in their [blank_start]outer[blank_end] shells.

Simple Covalent Bonds have a high melting/boiling point.

Diamond and Graphite are both made purely of carbon. Graphite can conduct electricity because it has [blank_start]delocalised[blank_end] electrons.

[blank_start]Ionic[blank_end] compounds cannot conduct [blank_start]electricity[blank_end] in their [blank_start]solid[blank_end] forms, but can when [blank_start]molten[blank_end]. This is because the charged [blank_start]ions[blank_end] are free to move in a [blank_start]liquid[blank_end], and can carry a [blank_start]charge[blank_end].