Basic chemistry help!

It's a very basic exercise to create a lewis structure, but I am confused as to how to get the correct amount of electron needed. My molecule is NaHCO3, since it's ionic I picked out HCO3 (-1)...

then I get the electrons Needed which are 2(H) + 8 x 4 (C and 3 O) = 34

Then the electrons Available: 1(H) + 4(C) + 3x6 (O) + 1 = 24

Finally Shared electrons: 34 - 24 = 10 (covalent bonds: 10/2 = 5)

But I am still confused with this example, why 2 Hydrogens and 8 x 4 Carbon and Oxygen... I know there are 3 oxygen but what about the other 2?

(I'm a high school student, a simple answer would be great xD)

It is both Ionic and covalent

take out the Na+ put it to the side

Draw HCO3-

Here is carbonate, just add an H

http://www.kentchemistry.com/links/bondi…