Understanding Parentheses in Chemical Formulas

[Willis666]

I was practicing some balancing chemical equations for a chemistry test, and I noticed this:
Cu(NO3)2 (numbers are subscripts.)

I've never seen parenthesis in a chemical formula before, no clue what it means. Nothing in my textbooks, and I can't really ask the teacher since the test is tomorrow.

The equation was in my book, so its not going to be something I have yet to learn.

Here's the full, unbalanced equation.

Cu + AgNO3 ----> Cu(NO3)2 + Ag

Sorry if this is a really stupid question, i don't know much about chemistry (i know what i learn in class.)

 

[Simon Bridge]

It means that the entire molecular ion inside the parentheses appears twice, as in:

NO₃^- -- Cu²⁺ -- NO₃^-

 

[Ygggdrasil]

It basically means that there are two of the chemical species within the parentheses. Cu(NO₃)₂ means that the substance has two NO₃^- ions for every one Cu²⁺ ion. You could very well write this as CuN₂O₆, but keeping it written as Cu(NO₃)₂ helps to emphasize that it consists of Cu²⁺ and NO₃^- ions.

 

[Willis666]

Okay, thanks.

 

[keisu]

And also Cu(NO3)2...Cu^2+ and NO3 ^-1, remember the charges come down, so that's how you get Cu1(NO3)2