Download forming ions

Intermediate 2 Chemistry
Formation of ions
August 2002
Dr. K Alder
Neutral atoms
• Neutral atoms have
the same number of
electrons and protons
12+
magnesium Mg 2,8,2
12 electrons
August 2002
Dr. K Alder
-
12 protons +
Ions
• ions are atoms that have an unequal number of
electrons and protons
• atoms gain or lose electrons to become ions
• number of protons DOES NOT change
August 2002
Dr. K Alder
• Positive ions form by losing electrons
12+
12+
magnesium Mg2+ 2,8
magnesium Mg 2,8,2
12 electrons
August 2002
-
12 protons +
10 electrons
Dr. K Alder
-
12 protons +
ions
Mg
Mg
2+
Neutral atom
Positive ion
Atomic number = 12
Atomic number = 12
Protons = 12
Protons = 12
Electrons = 12
Electrons = 10
Equal protons and
electrons give no
charge
August 2002
Two fewer electrons gives an
overall charge of 2+
Dr. K Alder
•Negative ions form by gaining extra electrons
17+
17+
chlorine Cl 2,8,7
chlorine Cl- 2,8,8
17 electrons
August 2002
-
17 protons +
Dr. K Alder
18 electrons
-
17 protons +
ions
Cl
Cl
-
Neutral atom
Negative ion
Atomic number = 17
Atomic number = 17
Protons = 17
Protons = 17
Electrons = 17
Electrons = 18
Equal protons and
electrons give no
charge
August 2002
One extra electron gives an
overall charge of 1Dr. K Alder