Topic 7 - Bonding
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What are the 3 types of bonding?
Ionic bonding, covalent bonding and metallic bonding.
What is ionic bonding?
An attraction between oppositely charged ions.
Where are ionic bonds found?
In compounds made of metals and non-metals.
What is covalent bonding?
2 atoms sharing 1 or more pairs of electrons.
Where are covalent bonds found?
In most non-metal elements and in non-metal compounds.
What is metallic bonding?
An attraction between positively charged ions and negatively charged delocalised electrons.
Where are metallic bonds found?
Metallic bonds are found in metals and alloys.
What is an alloy?
A mixture of metals and other substances.
What is an ion?
Particles that have a charge, created when an atom or molecule gains or loses electrons.
What causes a negative ion?
Gaining electrons
What causes a positive ion?
Losing electrons
What is a positive ion called?
Cation
What is a negative ion called?
Anion
What happens during ionic bonding?
In ionic bonding, a metal atom transfers electrons to a non-metal atom, allowing both to have a full outer shell.
What are the properties of materials with ionic bonds?
Only conduct electricity when molten/dissolved, high melting points.
What are dot-and-cross diagrams used for?
To show electrons being transferred and ions being formed in covalent or ionic bonding.
What do the dots represent?
Electrons from 1 atom.
What do the crosses represent?
Electrons from the other atom.
What else must a dot-and-cross diagram have?
Square brackets and a charge (e.g. 2+) to represent ions.
When are ionic compounds formed?
When millions of metal atoms transfer electrons to millions of non-metal atoms at the same time, resulting in ionic lattices.
What are ionic lattices?
Giant structures held together by large electrostatic forces between positive and negative ions.
What are electrostatic forces?
Ionic bonds that extend in all directions.
What are empirical formulae?
The simplest ratio of ions possible where charges are balanced.
Examples of covalent bonds?
Small molecules (e.g. Water), large molecules (e.g. polymers) and giant covalent structures (e.g. diamond).