The Open Door Web Site
Atoms and Ions
An ion is a charged ( + or - ) particle there are different types:
Cations and anions
Remember that atoms are electrically neutral, if an atom gains or loses electrons then it becomes charged
= an electron
If an atom loses electrons it becomes positively charged (Cation)
Example :Sodium atom has 11 electrons it loses 1 electron to form a Sodium ion which has 10 electrons.
If an atom gains electrons it becomes negatively charged (Anion)
Example: Chlorine atom has 17 electrons it gains 1 electron to become a Chloride ion which has 18 electrons. The number of protons positive charges does not change).
Atom: 17- 17+ so no charge
Ion: 18- 17+ so charge of 1-
The atom gains or loses electrons so that it has a full outer shell of electrons.
The anions and cations combine together to form an electrically neutral compound. These compounds are called ionic compounds.
Aqueous solutions of ionic compounds conduct electricity, due to the presence of the ions.
These are ions that are made up of 2 or more different atoms. (Positively charged - cation, negatively charged - anion)
Note: Images not to scale!
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