Bonding
Covalent
Ionic
Metallic
2 Non-metals that share electrons to gain a full outer shell.
A simple molecule consists of a small number of atoms joined together by covalent bonds.
Diatomic molecules are the same element bonded with itself (e.g. all halogens, oxygen, nitrogen, hydrogen.)
The bonding in these molecules can be modelled by using a dot and cross diagram, in which the outer shell of an atom is drawn as a circle, the circles overlap each other where there is a covalent bond, and the electrons from one atom are drawn as dots and the electrons from the other atom are crosses.
A molecule can either be an element (if its atoms are the same non-metals), or a compound (if its atoms are different non-metals).
A molecule consists of two or more non-metal atoms joined together by covalent bonds.
Easily broken with a small amount of energy.
Low mpt and bpt.
A simple molecule can be modelled by drawing its structure, in which these models show each atom by its element symbol and each covalent bond as a straight line.
Small molecules/simple structures such as these have weak intermolecular bonds.
The bonding process between a metal and a non-metal.
The metal will give the electrons and the non-metal will receive them.
Groups will bond to make a full outer shell.
‘-’ or ‘+’ shows how many electrons they have given (positive ion) or taken (negative ion).
Only the outer shell is shown in a diagram - metals will be empty and non metals will be full.
‘X’ represents the donated electrons from the metals.
Empirical formula given by how many elements there are - For example;
Only one for first 2 and then 1 Ca and 2 F for last.
Square brackets show ions in a diagram.
Allotropes
Nanoparticles
Strong intermolecular forces between the polymer molecules so they have a higher melting and boiling point and tend to be solids at room temperature.
Allotropes of Carbon - Different forms of covalently bonded Carbon.
Diamond has lots of very strong covalent bonds.
Silicon Dioxide - All bonds are used up. It is a strong covalent structure.
Graphite - Each carbon atom forms bonds with 3 (1 is delocalised) others to make layers of hexagonal rings.
Each carbon atom is bonded with 4 others (carbon valency is 4).
It is therefore hard and has a very high mpt.
The layers are able to slide over each other because there are weak intermolecular bonds.
Therefore conducts and are used as lubricants.
Allotropes of Carbon (Giant Covalent Structures)
Graphene - Single layer of graphite (carbon) one atom thick
Fullerenes
Made of carbon atoms but have a hollow shape.
Based on hexagonal rings of carbon but can have rings made of atoms.
High tensile strength
Used for drug delivery, lubricants and reinforcing materials