What principle do we use in writing the formula of an ionic compound such as NaCl or MgI2? How do we know that two iodide ions a

Question

3 years ago

14

re needed for each magnesium ion, whereas only one chloride ion is needed per sodium ion?

1 answer:

Savatey [412] · Answer 1 · 2021-12-03T06:59:26+03:00

Answer:

We know based on the charges of each ion and the fact that they must always sum to 0

Explanation:

Na only has one outer electon to give so it is always +1

Mg has two outer electrons so it always gets +2

Halogens have one "missing" electron in their outer shell so they get a -1

For NaCl (+1) + (-1) = 0

For MgI2 (+2) + 2(-1) = 0