CHM 243 - lewis structures & geometry

__________ on the period table must follow the octet rule. Common elements that must follow the octet rule include:

period 2

C, N, O, F

How do we determine what the "best" or "most acceptable" Lewis Structure is?

the best is the Lewis Structure with the smallest possible formal charges
on EACH ATOM

Draw bicarbonate’s ion structures

HCO₃⁻

Answer:

What is the formal charge of each atom of each of bicarbonate’s structures. Use this to find the best structure:

The structure to the right is the better structure, because 4 of those atoms have a formal charge of 0 (only the bottom O has a formal charge of -1)

The structure to the left only has 2 atoms with a formal charge of 0 (bottom O has FC = -1, left O has FC = -1, and right O has FC = +1)

In general, negative charges are BEST placed on atoms with __________ electronegativity, for example __________
Positive charges are BEST placed on atoms of __________ electronegativity, for example, __________

neg charges on high electronegative atoms

Examples: O, N, halogens

pos charges on low electronegative atoms

Example: metals

What are the 5 possible electron arrangements, and how many electron domains are there around the central atom for these arrangements?

Linear → 1 or 2 domains

Trigonal planar → 3 domains

Tetrahedral → 4 domains

Trigonal Bipyramid → 5 domains

Octahedral → 6 domains

If there are LONE PAIR electrons on the central atom, what does this mean for it’s geometry?

the electron geometry and molecular shape is the same

Fill in the chart:

Answer:

Fill in the chart:

Answer:

Fill in the chart:

Answer:

Fill in the chart:

Answer:

Fill in the chart:

Answer:

Fill in the chart:

Answer: