Chemistry Unit 2

Annotations:

• Elements react to form compounds by gaining or losing electrons Atoms of metals in Group 1 combines with atoms of non metals in Group 7 by transferring electrons to form ions that have the electronic structures of noble gases

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• Ionic compounds are held together by strong forces between the oppositely charges ions. This is called ionic bonding. Ionic bonding occurs between metals and non metals. The ions form a giant structure or lattice. The strong forces of attraction act throughout the lattice.

1. Annotations:

   • We can use dot and cross diagrams to represent the atoms and ions involved in forming ionic bonds. In these diagrams we only show the electrons in the outermost shells of each atom or ion.   

2. Annotations:

   • Part of the giant ionic lattice (3D-network) of sodium and chlorine ions in sodium chloride The strong bonds between oppositely charges ions

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• The charges on the ions in an ionic compound always cancel each other out The formula of an ionic compound shows the ratio of ions present in the compound Sometimes brackets are needed to shoe the ratio of ions in a compound, eg. magnesium oxide, Mg(OH)2