Inside the AtomPeriodic Table

Covalent Bonding

Electron Shells

• Contain all electrons at approx. same energy and distance out.

Shell Number designation

Electron capacity (2n*n)

1st 1 2

2nd 2 8

3rd 3 18

4th 4 32

5th 5 50

Valence Electrons

Electrons in outer shell– Farthest out– Most loosely held

• Most likely to be involved in a chemical reaction

Periodic Law

• Attributed to Mendeleev – 1869• Similar properties occur @ regular intervals

(periods)• Based on experimental results (laws)• Didn’t know why (theory) until electron orbits

or shells were discovered

Representative Elements

Halogens

Valence Electrons

• Equal to the number of the column for representative elements– So all elements in a column have same # of

valence electrons (representative)– Valence electrons determine chemical

behavior– Example Ca and Sr

Lewis or Electron Dot Structure

• Number of dots = number of valence electrons = number of column.

Octet Rule of Bonding

• All but smallest atoms want to have 8 valence electrons

• Or all atoms want to be like the closest Noble Gas– Lose electrons– Gain electrons– Share electrons – Covalent Bonding

Ionic Bonding

Covalent Bonding

• Sharing electrons instead of transferring – H + H → H H– Cl + Cl → Cl Cl

– H + O + H → H O H or H – O – H

H H – 4H + C → H C H or H – C – H

H H

Nobel gasconfiguration

Water

Covalent Bonding

• Number of bonds an atom wants to form?– Equal to number of electrons it is missing to

be like a noble gas

• How many O’s will react with C ?

• How many F’s will react with N ?

Multiple Covalent Bonds

• Single bond – share one pair of electrons

• Double bond – share two pair

• Triple bond – share three pair

• All but group VIIA and H can double bond

• Group IVA & VA can triple bond– Mostly C, N, Si, P

Naming Binary Covalent Compounds

Naming Binary Covalent Compounds

Shapes of Compounds

• You will get a good feel for shapes in lab 5

H8 – C3

• 16, 18, 19, 21 - 25, 27, 28, 31, 32, 55, 56, 60, 62, 64, 80