Question

1. refer to the bohr models above: element c is in period _. element b is in period _. element b has (lower, higher) shielding effect compared to element c. element a is in group _. element b is in group _. element c is in group ___. 12. what is the oxidation number (charge) for each of the following? rb -1 br -3 n +3 al +2 mg -2 s

Explanation:

Step1: Determine oxidation number rules

Oxidation number of a mon - atomic ion is equal to its charge.

Step2: Analyze each element

• For Rb (rubidium), it is in group 1 and forms a + 1 ion, so oxidation number is + 1.
• For Br (bromine), it is in group 17 and commonly has an oxidation number of - 1 in compounds.
• For N (nitrogen), in many compounds it can have an oxidation number of - 3. For example, in ammonia ($NH_3$), hydrogen has an oxidation number of + 1, and to balance the charges in the neutral molecule, nitrogen has an oxidation number of - 3.
• For Al (aluminum), it is in group 13 and forms a + 3 ion, so oxidation number is + 3.
• For Mg (magnesium), it is in group 2 and forms a + 2 ion, so oxidation number is + 2.
• For S (sulfur), it is in group 16 and can have an oxidation number of - 2 in many compounds like hydrogen sulfide ($H_2S$).

Answer:

Rb: + 1
Br: - 1
N: - 3
Al: + 3
Mg: + 2
S: - 2