Ions and Atoms

Ions and Atoms

1. Positive ions

   • For most metal ions the charge on the ion will be given by the group number
     • E.g. by how many electrons hey lose from their outer shell
   • Examples of positive ions are in sodium(Group 1) and aluminium(Group 3)
   • Other elements are hydrogen(H+), copper(CU2+), iron(Fe+) and silver(Ag+)

2. Negative Ions

   • For negative ions the charge can be worked out by using the rule(8-group number) to work out the number of electron that they gain in their outer shell
   • Example of negative ions are Chlorine(Group 7). Chlorine has a symbol of Cl-
     • Another example is Oxygen(Group 6). Oxygen has a symbol of 02-

3. Complex Ions

   • Sometimes an ion may be formed by a group of atoms joined together
     • This is known as a complex ion
   • Examples of complex ions are
     • Hydroxide(OH-)
     • Sulphate(S04-2)
     • Sulphite(S03-2)
     • Carbonate(C03-2)
     • Nitrate(N03-)

4. Line Spectrum

   • All atoms give off light when heated, although sometimes this light is not visible to the human eye
   • A prism can be used to split this light to form a spectrum, and each element has its own distinct line spectrum
     • This technique is known as spectroscopy
   • Scientists have used line spectrum to discover new elements. In fact, the discovery of some elements, such as rubidium and caesium, was not possible until the development of spectroscopy. The element helium was discovered by studying line spectra emitted by the Sun

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