1. IONS
Big Idea
Atoms can gain or lose electrons to form charged particles called IONS

2. Orbitals Each electron in an atom has a definite amount of energy.
Orbitals that are FULL of electrons are most stable.
What neutral atom has this many electrons?

3. What are Ions?
Atoms are neutral particles because they have the same number of positive protons and negative electrons.
An ion is a charged particle.
An ion is formed when an atom gains or loses electrons.

4. Forming Ions Type of Ion How Formed? Example Negative Ion = anion
Formed by gaining negative electrons
F  F-1
Positive Ion
= cation
Formed by losing negative electrons
Na  Na+1

5. Atoms want noble gas orbitals!
Noble gases have stable energy levels for their orbitals.
Atoms want to form ions with the most stable energy levels.
To form ions atoms in groups 1, 2, 13 will lose valence electrons.
To form ions atoms in groups 15, 16, 17 will gain valence electrons.

6. Forming a Fluorine Anion
Fluorine Ion has a -1 charge!
Fluorine Atom (F)
Atomic mass = 19 +
Atomic Number = 9 9p
10n
# protons = 9
# neutrons = 10
# electrons = 9
Total charge in fluorine atom = +9 plus -9 = 0
Total charge in fluorine ion = +9 plus -10 = -1

7. Forming a Magnesium Cation
The neutral magnesium atom Mg has
Atomic mass=24
Atomic number=12
12 protons
12 neutrons
12 electrons
Total charge on magnesium atom=0
A magnesium ion is formed by losing 2 valence electrons.
12p
12n
This forms a cation, Mg+2

8. Pattern for Ionic Charges
Group # 1 2 13 14 15 16 17 18
# of Bonds? 3 4
Gain or Loss of Electrons?
Loss X
Gain
Of How Many Electrons?
Ionic Charge? +1 +2 +3 -3 -2 -1

9. Noble Gas Orbitals
When the orbital contains a full set of electrons, the atom is said to have a stable noble gas orbital.
First orbital : 2 electrons to be full (complete)
Second orbital : 8 electrons to be full (complete)
Third orbital : 8 electrons to be full (complete)
Group 14 and 18 atoms do NOT form ions!!!

10. Test Yourself What ion will calcium form? Ca+2
Will sulphur gain or lose electrons to form an ion?
Gain 2 electrons
How is a cation formed?
By losing electrons, so there are more positive protons left.