Author Question: Following are several Lewis structures showing all valence electrons. Assign formal charges in each ... (Read 236 times)

MirandaLo · **on:** Aug 23, 2018

Following are several Lewis structures showing all valence electrons. Assign formal charges in each structure as appropriate.

Question 2

Following the rule that each atom of carbon, oxygen, and nitrogen reacts to achieve a complete outer shell of eight valence electrons, add unshared pairs of electrons as necessary to complete the valence shell of each atom in these ions. Then assign formal charges as appropriate.

Question 3

Some of these structural formulas are incorrect (i.e. they do not represent a real compound) because they have atoms with an incorrect number of bonds. Which structural formulas are incorrect, and which atoms in them have an incorrect number of bonds?

Question 4

Write Lewis structures for these ions. Show all valence electrons and all formal charges.
(a) NH₂^-
(b) HCO₃^-
(c) CO₃^2-
(d) NO₃^-
(e) HCOO^-
(f) CH₃COO^-

Question 5

Write Lewis structures for these compounds. Show all valence electrons. None of them contains a ring of atoms.
(a) H₂O₂

(b) N₂H₄

(c) CH₃OH

Question 6

Judging from their relative positions in the Periodic Table, which atom in each set is more electronegative?
(a) Carbon or nitrogen
(b) Chlorine or bromine
(c) Oxygen or sulfur

briezy · **Reply #1 on:** Aug 23, 2018

Answer to Question 1

There is a positive formal charge in parts (a), (e), and (f).
There is a negative formal charge in parts (b), (c), and (d).

Answer to Question 2

The following structural formulas show all valence electrons and all formal charges for clarity.

Answer to Question 3

The molecules in (a), (b), (d), and (f) are incorrect, because there are five bonds to the circled carbon atom, not four

Answer to Question 4

Amide ion

Bicarbonate ion

Carbonate ion

Nitrate ion

Formate ion

Acetate ion

Answer to Question 5

(a) H₂O₂
Hydrogen peroxide

(b) N₂H₄
Hydrazine

(c) CH₃OH
Methanol

Answer to Question 6

(a) Carbon or nitrogen
In general, electronegativity increases from left to right across a row (period) and from bottom to top of a column in the Periodic Table. This is because electronegativity increases with increasing positive charge on the nucleus and with decreasing distance of the valence electrons from the nucleus. Nitrogen is farther to the right than carbon in Period 2 of the Periodic Table. Thus, nitrogen is more electronegative than carbon.

(b) Chlorine or bromine
Chlorine is higher up than bromine in column 7A of the Periodic Table. Thus, chlorine is more electronegative than bromine.
(c) Oxygen or sulfur
Oxygen is higher up than sulfur in column 6A of the Periodic Table. Thus, oxygen is more electronegative than sulfur.