Chemical Bonding

1. Chemical Bonding

2. Electron orbitals and the Octet Rule • All atoms want to be happy. • What makes an atom happy? • An atom with a full outer shell of electrons! • The Octet Rule • Atoms tend to gain, lose or share electrons in order to have a full energy shells.

3. Atomic radius decreases  ionization energy increases  electronegativity increases

4. Elements with 1-3 electrons will lose their electrons. • Elements with 4-8 will gain electrons. • The tendency to attract electrons is called electronegativity. • Electrons carry a negative charge.

5. Ionic Bonding

6. Ionic bonds form between metals and nonmetals. • In naming simple ionic compounds, the metal is always first, the nonmetal second (e.g., sodium chloride). • Ionic compounds dissolve easily in water and other polar solvents. • In solution, ionic compounds easily conduct electricity. • Ionic compounds tend to form crystalline solids with high melting temperatures. • This last feature, the fact that ionic compounds are solids, results from the intermolecular forces (forces between molecules) in ionic solids.

8. Physical properties Metals Chemical properties 1-3 valence electrons Lose electrons easily Lower electronegativities Bond ionically with non-metals Lustrous High melting points High density Good conductors of heat/ electricity Ductile Usually solid at room temperature Opaque in thin sheets Lustrous/shiny

9. Physical properties Non-metals Chemical properties Usually have 4-8 valence electrons Have higher electronegativities Good oxidizers bond ionically with metals Bond covalently Not lustrous Poor conductors of heat/electricity Nonductile Brittle May be solids, liquids or gases at room temperatures. Transparent in thin sheets