chemistry work sheet.

LAB 2: LEWIS STRUCTURES For this lab we will be practicing Lewis Structures.

Remember from the slides that there are rules. If you follow the rules stepwise – it will always work out.

RULES

1. determine the total number of valence electrons

· If it is a negative ion – add an additional electron(s)

· If it is a positive ion – subtract electrons

2. Determine what the central atom is and connect the other atoms

· Use a dash line to show the connections

· The dash line represents 2 valence electrons

· Subtract these electrons from the total

3. distribute the remaining electrons around the peripheral ( not central atom) making 1 fulfill the octet rule before moving on the other

· Use dots to represent the electrons

· The electrons must be in pairs (lone pair)

· If there are any electrons left over – put them on the central atom

4. Check to see of all atoms obey their octet rule.

· If the central atom does not have enough electrons, move a lone pair from the peripheral atom to between that atom and the central atom

Remember

· you also need the rules for the VSEPR (Valence Shell Electron Pair Repulsion) theory

· chart for electronegativity chart

Please submit the chart below

Molecule	Number of valence electrons	Lewis structure	Molecular Geometry	For Each Bond, is it polar or non-polar	Is the overall molecule polar or nonpolar
CH4
H2O
NO3-
NH4+
CO2
CH2O
CH3Cl
H3O+
Molecule	Number of valence electrons	Lewis structure	Molecular Geometry	For Each Bond, is it polar or non-polar	Is the overall molecule polar or nonpolar
NH3
ClO2-
SO2
SO4-2