Chemistry bonding

C3.4 Ions and Ionic bonds

Ions are electrically charged particles formed when atoms lose or gain electrons.

Metal atoms form positive ions and nonmetal atoms form negative ions. The strong electrostatic forces of attraction between oppositely charged ions are called ionic bonds

Dot and cross digram:

Metallic elements lose electrons to become positively charged and non-metals gain electrons to become negatively charged.

The oppositely charged ions are arranged regularly to form a giant ionic lattice:

C3.5 Molecules and covalent bonds

A covalent bond is formed by two NON-METAL atoms which combine together by sharing electrons. When two or more non-metal atoms are joined by covalent bonds we call them molecules.

Summary:

Ionic bonding- 

• Non-metal and metal
• Electrons are lost or gained,
• the bond is a electrostatic force between opposite ions,
• very high boiling point ( strong bonds),
• soluble in water,
• only conducts when melted or dissolved because the ions are free to move. 

Molecular (covalent)-

• Two Non-metals
• electrons are shared
• the bond is the shaired pair of electrons
• very low boiling point (weak intermolecular force)
• insoluble in water
• no charged particles so does not conduct

Metallic- 

• between metals
• electrons are delocalised
• bond is electrostatic force between electrons and positive ions
• very high boiling point
• insoluble
• electrons are free to move (delocalised) so can conduct

Covalent bonds between atoms…