Question

Why do we call Mg(NO3)2 magnesium nitrate, but we call Ni(NO3)2 Nickel(II) nitrate?

Answer 1

Because Nickel is a transition metal that has more than one oxidation number (or charge) whereas magnesium always has a +2 charge.

Answer 2

Answer: Because nickel is a transition metal.

Step-by-step explanation:

We are given two compounds named as magnesium nitrate
`(Mg(NO_3)_2)` and Nickel (II) nitrate
`(Ni(NO_3)_2)`

Both the compounds are ionic compounds and its naming is done as follows:

1. Positive is written first.
2. The negative ion is written next and a suffix is added at the end of the negative ion. The suffix written is '-ide'.
3. If the metal ion is a transition metal, then the oxidation state is written in roman numerals inside the bracket. This is so done because transition metals show variable oxidation states.

Hence,
`Mg(NO_3)_2` is written as magnesium nitrate and
`Ni(NO_3)_2` is written as Nickel (II) nitrate due to variable oxidation state shown by transition metals.