1. Chemical Bonding Chapter 13 Ionic Bonds Section 2

2. Reminder… Valence Electrons effect the bonding of atoms
The happy magic number is… 8

3. Electron Transfer
Atoms with 1-3 electrons will lose e- to become stable. Metal donor
stable – an atom with a full valence shell
Atoms with 5-7 electrons will gain e- to become stable. Nonmetal receiver

4. Charge of An Atom IF… # of protons = # of electrons
the atom becomes an ION
ion – is an atom or group of atoms that has become electrically charged.

5. Charge of An Atom If # protons > # electrons = positive charge
atom loses electron
CATION
If # protons < # electrons = negative charge
atom gains electron
ANION

6. Ions
CATION (+)
ANION (-)

7. Forming an Ionic Bond
Sodium donates an e- and becomes positively charged. Na+
Chlorine gains an e- and becomes negatively charged. Cl-
Positive sodium and negative chlorine attract each other.
Sodium chloride (table salt) is formed. NaCl
ionic bond - attraction between two oppositely charged ions.
Compounds are electrically neutral. Atoms form compounds for this reason and will join with other atoms that will give each one a full valence shell.

8. Polyatomic Ions
Ions that are made of more than one atom are examples of polyatomic ions. Poly means many.
Each polyatomic ion has an overall negative or positive charge.
Ex: carbonate (CO32- ) can combine with calcium (Ca2+) to form calcium carbonate (CaCO3 ).

9. Naming Ionic Compounds
The name of the positive ion comes first.
If the negative ion is an element, the end of the element name is changed to -ide.
If the negative ion is polyatomic, its name is unchanged.

10. Properties of Ionic Compounds
Crystal Shape
High Melting Points -- ex: Salt 801ºC
Electrical Conductivity
A solid ionic compound does not conduct electricity very well b/c the ions are tightly bound to each other.
When ionic compounds dissolve in water, the ions separate and the solution will conduct electricity.
In an ionic compound, every ion is attracted to ions near it that have an opposite charge.