1. What is the purpose of the parentheses in the compound magnesium cyanide, Mg(CN)2?
2. Why are the 3’s not simplified in the aluminum nitrate formula, above?
3. In the compound potassium oxalate, K2(C2O4), why are the 2’s and the 4 not simplified?1. The purpose of the parenthesis is to indicate that there is two molecules of cyanide (CN) in the compound magnesium cyanide.
2. Aluminum has a positive 3 charge which is cancelled out by the negative 3 charge that a nitrate carries. Hence they aren’t written in the formula as +3 -3 = 0
3. The 2s and 4s in potassium oxalate describe how many molecules of potassium, carbon, and oxygen are present. There are 2 potassiums, 2 oxygens, and 4 carbon in potassium oxalate. (You can look at the structure of the chemical compound for deeper understanding)Hope that helps!
As a general point, subscripts indicate how many molecules a substance there are. E.g., H2O has 2 molecules of hydrogen for every 1 molecule of oxygen. That being said:
1. The parentheses are used to indicate that something (the thing inside the parentheses) is attached to something (the thing outside the parentheses). It is used when more than 1 molecule of something is attached to another thing. Comparing HCN and Mg(CN)3, you can see that 1 hydrogen molecule and 1 cyanide molecule are needed to form the HCN compound. However, when 1 magnesium molecule is considered, you would need 3 cyanide molecules to form the Mg(CN)3 compound.
2. Al(NO3)3 is a neutral compound; having a net charge of 0. Al on its own has a charge of +3. NO3 on its own has a charge of -1. In order to cancel each other out and form the neutral Al(NO3)3 compound: 1 * (3) Al + 3 * (-1) NO3 = 1 Al(NO3)3.
3. The subscripts are representative of many of each molecule you have. You have 2 potassiums, 2 carbons and 4 oxygens.
Note that the parentheses are not needed for this compound in particular, however, they do help with identifying that C2O4 (oxalate) is a compound in and of itself, rather than just 2 carbon atoms and 4 oxygen atoms. Oxalate has its own charge/characteristics, like CN (cyanide). CN is always CN, never C2N2 or C3N3. Oxalate is the same way; always C2O4.
1. What is the purpose of the parentheses in the compound magnesium cyanide, Mg(CN)2?
2. Why are the 3’s not simplified in the aluminum nitrate formula, above?
Aluminum positive charge of 3 balances out nitrate negative charge of -3
3. In the compound potassium oxalate, K2(C2O4), why are the 2’s and the 4 not simplified?
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