Bonding

Bonding

• During chemical reactions, atoms combine through a process called bonding to form new substances.

• Bonding occurs in the electrons.

Goal of Bonding

• The goal of bonding is to fill the valence, or outermost shell, with 8 electrons.

Periodic Table

• On the Periodic Table, all “A” columns show the number of electrons in the valence.

• All “B” columns have 2 valence electrons.

Example

• H + H -> H₂O

• Hydrogen has one valence

• Oxygen has six

• They bond to form a valence of eight

Two Basic Bonds

• There are two basic types of bonds: ionic and covalent. The following table shows the properties of each:

Ionic Bonds Covalent Bonds

•Bonds form ions •Bonds form molecules

•Lose & gain electrons •Share electrons

•High melting point •Low melting point

•High boiling point •Low boiling point

•Soluble in water •Insoluble in water

•Insoluble in solvent •Soluble in solvent

•Conducts electricity •No conductivity in water

when dissolved in water

Bonding Changes Properties

• The properties of new substances are different from the elements which formed them.