BONDING

Bonds Between Atoms Covalent Ionic Molecular Substance Network Solids Metallic Metals Alloys

Ionic Bonds - results from the TRANSFER of electrons from a metal to a non-metal - the resulting ions are held by electrostatic forces in a 3D lattice

Example 1

Magnesium Oxide

Potassium Oxide

Characteristics: 1. Crystalline at room temperatures 2. Have higher melting points and boiling points compared to covalent compounds 3. Soluble in water Soluble 4. Conduct electrical current in molten or solution state but not in the solid state 5. Brittle

Empirical Formula Is the simplest ratio of atoms present in a compound Eg. NaCl

Covalent Molecular - results from SHARING of electrons between 2 non-metals Yields a neutral molecule

Forces

Characteristics: 1. Has weak intermolecular forces among adjacent neutral molecules which contributes to its low melting points and boiling points. The stronger the intermolecular force, the more energy needed for phase changes 2. Do not conduct electrical current

Covalent Network Solids when atoms are bonded together covalently to form an infinite orderly array in 3 dimensions network solids are extraordinarily strong

Diamond Each Carbon atom bonds to 4 others Strong covalent bonds throughout High melting points and Boiling points No free electrons so does not conduct electricity.

Graphite Each Carbon atom is bonded to 3 others The bonding within the layers is strong covalent. The spare fourth electron of each C atom is delocalised so graphite can conduct electricity There are weak intermolecular forces of attraction between the layers.

Silicon Dioxide: Sand & Quartz SO2

Metallic Bonding Metals normally occur as solids (high melting points) Thus, there must be strong bonds between the atoms of metals

Metallic Bonding positive nuclei exist in a sea of delocalised electrons (this explains why metals conduct electricity)

Properties of Metals Metals are easily bent, rolled into sheets (malleable) and drawn into wires (ductile). The mobile electrons will shift to adjust to new arrangements of its positive ions. They act as the "glue".