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rivs9 rivs9
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Posts: 111
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11 years ago
Write formulas and names for compounds composed of ions of following metals and the indicated polyatomic ions:

A. magnesium and the hydroxide ion
B. sodium and the dichromate ion

Please explain. Thank you!
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irinairina
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11 years ago
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wrote...
11 years ago
A. Magnesium hydroxide Mg(OH)2

B. Sodium Dichromate Na2CrO7

Names are sort of self-expalanatory.
The reason I have used two hydroxide ions for every magnesium is that magnesium has a valency of 2, which means in this case it forms ions with 2 positive charges whereas hydroxide has a valency of 1 (one negative charge) To balance them and keep the salt electrically neutral we need a 1:2 ratio.formulae

A similar thing applies to sodium dichromate. Sodium has a valency of 1 Na+)and dichromate has a valency of 2 (CrO7-)  hence a 2:1 ratio here.
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