1. Forming Compounds
Science 10
Ms. McGrath

2. Important terms You should be familiar with the following terms:
ionic compound
ion

3. Forming Compounds
The goal of every atom is to become stable (full valence shell)
Ex. : Na +, Mg 2+, Al  Have the same number of electrons as the noble gas neon

4. Ions When atoms carry an electrical charge they are called ions.
Ions are atoms or groups of atoms with a
positive or negative charge.
Ions are created by atoms losing or gaining,
one or more electrons.

5. Ions - Cations
When a neutral atom loses an electron, a positively charged ion results. This is called a cation
(cat-eye-on).
For example: Na (Sodium) has 11 protons and 11 electrons. It is a neutral sodium atom. It has 1 valence electron. Adding energy to a neutral sodium atom removes the valence electron, leaving a positively charged sodium ion and a free electron.

6. Ions - Cations
Example: Sodium, Na

7. Ions - Anions
When a neutral atom gains an electron, a negatively charged ion results. This is called an anion
(an-eye-on).
For example: Cl (Chlorine) has 17 protons and 17 electrons. It is a neutral chlorine atom. It has 7 valence electrons. Adding energy to a neutral chlorine atom adds one valence electron, leaving a negatively charged chlorine ion.

8. Example: Chlorine, Cl

9. Ions - Conclusion
When an atom loses an electron, it becomes a positively charged ion (+), or a cation.
When an atom gains an electron, it becomes a negatively charged ion (-), or an anion.

10. Ionic Compounds Metals form positive ions
Non-metals form negative ions
So metals and non-metals bond together to create ionic compounds with ionic bonds
Metals transfer their electrons to non-metals
Both will now have full and stable valence shells

11. Ionic Compounds In Summary: formed between a metal and non-metal
transfer electrons to become stable

12. Ionic Compounds – an example
Sodium chloride, NaCl
[Na] 1+ [Cl]1-

13. Ionic Compounds – an example
Calcium chloride, CaCl2

14. Ionic Compounds – an example
Lithium bromide, LiBr