Ionic Bonds

Electron dot structures

Show only the valence (outer) electrons Dots around symbol Equal dots to group number

Elements within the same group have the same electron-dot structure.

Valence Electrons

Valence electrons are the electrons in the highest occupied energy level of the atom. Last number in electron configuration

Valence electrons are the only electrons generally involved in bond formation.

Two types of bonds

Ionic: between a metal and a nonmetal, electrons are transferred

Covalent: between two nonmetals, electrons are shared

All bonds help fulfill the octet rule=all elements want 8 valence electrons

Except H, He, Li, and Be that want only 2

Na , 11 e

1s2 2s2 2p6 3s1

Na + , 10e

1s2 2s2 2p6

A Positive Ion (Cation):

An atom that has lost one or more electrons. + charge Metals form cations

Chlorine Atom Chlorine Ion

Cl

1s2 2s2 2p6 3s2 3p6

A Negative Ion (Anion)

An atom that has gained one or more electrons.

Negatively (-) charged. Nonmetals form anions

When Na, (11) loses its valence electron, what element does its configuration look like ?

a. Neon

b. Potassium

c. Beryllium

d. Sodium

Check your Neighbor

Ionic Bonds

Bonds that are formed by transfer of electrons from one element to the other.

Each element as an ion has a complete octet after the transfer of electrons.

Ionic Compound dot structures

1. show dot structures of original elements 2. Show arrows where electrons move 3. Show ending charges

Example: Formation of Lithium Fluoride

.Li. + : F :

..

The Ionic Bond

• The electrical force of attraction between oppositely charged ions holds the compound together.

Na+ F−

Naming ionic compounds

Put the metal name first Put the nonmetal name second but change

the ending to –ide NaCl

K2O

Ionic charges

Group 1=+1 Group 2= +2 Group 13=+3 Group 14=+/-4 Group 15=-3 Group 16=-2 Group 17=-1

Writing the formula for ionic compounds Write down the symbols and charges Criss cross the charges ignoring the signs Don’t write as subscripts 1

If the two charges are the same value there are no subscripts.