Ionic Bonds

Forming Salt

How many elements are there?

~118 elements are listed on the periodic table. So does this

mean there are only 118 different

substances that exist?

No!

Why?

•Elements can combine with each other to form compounds.

•Compound   A material formed by the chemical combination of elements in defined proportions.

Why do elements combine?Full Outer Shell = Happy Atoms

• Atoms are the most stable when their electron shells are full.

• Which family of elements are the “happiest?”

• Why don’t Noble Gases combine with any other elements?

• They don’t need any electrons!

Some atoms have one or two extra valence electrons

54 8762 31

These atoms give up their electrons These atoms give up their electrons easily--which families are they in?easily--which families are they in?

Some atoms are really close to having a full shell

54 8762 31

These atoms only need one more electron These atoms only need one more electron to be full--which family are they in?to be full--which family are they in?

•Formed when two or more atoms chemically bond together, the resulting compound is unique both chemically and physically from its parent atoms.  

•Let’s look at an example!

Table salt

NaCl

Sodium metal

Na

Chlorine gas

Cl

Sodium and Chlorine Reaction

Why do Na and Cl combine?

Sodium transfers its electron to chlorine, chlorine takes sodium’s electron.

Why do Na and Cl combine?

Loss or gain of electrons forms ions.

11p+

e-

e-e-e-

e-

e-

e-

e-

e-

e-Na11+

10-+

+1 charge

Loss or gain of electrons forms ions.

Sodium is a positively charged

ion because it LOST an electron.

PLEASE REMEMBER!

Ion formation only involves ELECTRONS being gained or lost.

Positive ions are NOT formed by gaining

protons!!!

Loss or gain of electrons forms ions.

Cl17+

18-+

-1 charge

17p+

e-

e-e-e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-

e-e-

e-

e-

Chlorine is a negatively charged

ion because it GAINED an

electron.

Opposites Attract•Ionic bonds form when there is an attraction between positive and negative ions.

•Ionic bonds involve a metal (positive charge) and a nonmetal (negative charge)

Ionic Compound or Not? (Click on Ionic Compound or Not? (Click on this title for a periodic table.)this title for a periodic table.)

1. NaCl

2. LiF

3. H2O

4. CaCl2

5. CO

6. MgO

7. C6H12O6

8. KBr

1. Ionic (metal Na & nonmetal Cl)2. Ionic (metal Li & nonmetal F)3. Not (two nonmetals)4. Ionic (metal Ca & nonmetal Cl)5. Not (two nonmetals)6. Ionic (metal Mg & nonmetal O)7. Not (two nonmetals)8. Ionic (metal K & nonmetal Br)

Charges of Ions

-3

+5

+4

-4

0-1-2+2 +3

-5

+1

What would you expect to bond in a 1:1 ratio?

-3

+5

+4

-4

0-1-2+2 +3

-5

+1

Ionic compounds are…•Crystalline solids at room temperature.•Crystalline solid: atoms, molecules, or ions that are packed in a regularly ordered, repeating pattern extending in all three spatial dimensions.

•Have high melting points and boiling points.

•Why? The strong bonding force between negative and positive ions takes a lot of energy to break.

Ionic compounds…

•Conduct electrical current in molten or solution state.

•To conduct electricity, free ions (charges) are needed.

Ionic compounds…

Can you explain this cartoon?Can you explain this cartoon?

Ionic Bonding Tutorial

• http://www.teachersdomain.org/asset/lsps07_int_ionicbonding/