Question

So in class examples today we were given compounds like calcium Bromide and where to come up with formulas for it like CaBr2. I took notes that this is because Ca has +2 charge and Bromide means that is has -1 charge. Can someone please explain to me how I can gather the info from periodic table about what kind of charge something like Ca has? I just wrote it down from class and do not really understand how to find this info on periodic table.

Answer 1

Another example was Calcium Carbonate which was then written as CaCo3

Answer 2

if you look at the periodic table you see that calcium is in group 2 . It has 2 electrons in its outermost shell and is electro -positive ( on the right of the PT) so its ion will have 2 positive charges

Answer 3

what do you mean electro - positive?

Answer 4

as for Br (bromine) its in Group 7: - 7 electrons in outer shell and is electro negative . To get the maximum stable outer shell which contains 8 electrons it tens to grab one electron in a chemical reaction so its its ion has1 negative charge

Answer 5

electropositive elements tend to donate electron and for positive charged ion
metallic elements like sodium, calcium, iron are electro positive.

Answer 6

Its not as simple as that all elements - for example tin ion can be Sn 2+ or Sn 4+


the above is a general rule

Answer 7

There is a concept called Oxidation Number which helps you find the formula of chemical compounds which you'll come across later in your studies.

Answer 8

Think I a starting to get it. Thanks!

Answer 9

Im looking up the(+) charged elements right now.

Answer 10

CaCO3
Ca ion is 2+

C atom has oxidation number 4
3 oxygen atoms is 3*2- = -6
so CO3 has charge of 4-6 = 2-

so Ca and CO3 combine to form the neutral CaCO3

Answer 11

some elements can have different charges
eg iron can be Fe++ or Fe+++

Answer 12

these usually belong to the Transition elements

Answer 13

Hope this helps
gotta go now