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Item C3b: How Atoms Combine Ionic Bonding
1. Atoms are neutral because they contain the same number of protons and electrons. Atoms
can lose or gain electrons from its shells. ( they cannot lose protons that easily, you'll never
asked about protons so you only need to learn about electrons lost or gained). If an atom of
group of atoms lose or gain electrons it becomes charged. When an atom or group of atoms
become charged their known as ions.
2. If an atom loses electrons it becomes positive, losing one electron makes it an ion with charge
+1 losing two electrons make it an ion with charge +2.
3. If an atom gains electrons then it becomes negative. Gaining one electron makes it 1 gaining
two electrons makes it an ion with charge 2.
4. Metals and nonmetals react to produce a type of compounds called ionic compounds. The
metal transfers one or more electrons to the nonmetal. The metal becomes positive ( as it
loses electrons) and the nonmetal becomes negative ( as it gains electrons). Now as they have
opposite charges and they attract each other. This attraction Is known as the ionic bonding.
5. For example, sodium (which is a metal) transfers one electron to chlorine atom. Sodium
becomes positive and chlorine becomes negative opposite charges attract each other and they
become the compound: sodium chloride.
6. Molecules are made up of more than one atom. ( they can be the same type of atom). From the
following circle all the molecules:
H2O Ag H2 Cu CH4 N2 O2 CuO Na2O Fe
7. Sodium chloride:
has a high melting point
dissolves in water
when solid it does not conduct electricity. When molten it will conduct electricity.
8. Magnesium oxide:
has a very high melting point
when solid does not conduct electricity.
9. Sodium chloride solution ( when dissolved in water) conducts electricity. ( Magnesium oxide
does not dissolve in water)
10. Magnesium oxide and sodium chloride conduct electricity when molten.