[noob_]

Simple question really ( I think):
I know that when bonding, atoms bonding try to be as further away from each other as possible.
So basically, if i were to draw H2S valence structure (2-D)
I would draw it like this:

                   S                   But why is it that i would not draw it like this:                H-S-H   ?
                  / \
                 H  H    
Thanks

Edit:
Also why is it BF3
And not BF5?
Boron has 3 valence electrons and needs additional 5 for stable outershell
Fluorine has 7 valence electrons and needs 1 electron for stable outershell
BF3 means that Boron will gain an additional 3 electrons, totaling 6 valence in it's outershell and not 8?
Edit #2: I just realised why it isnt BF5, B only has 3 outershell electrons -_-..
But i still don't get how the bond BF3 is made, only Fluorine has the complete outershell in this case?
Or BF3 like an emperical formula?

[Professor 0110]

It all comes back to electro-negativity. The sulfur atom has acquired a slight negative charge, whereas the hydrogen atoms have acquired slight negative charges. I believe (and I could be wrong) that you would not find H - S - H, the same way you would not suddenly have north and south side by side. The repulsion and the attraction of the hydrogen and sulfur bond bends it into that particular shape. Remember too that hydrogen atoms like to go around in pairs. I think that has something to do with it. If sulfur was in the middle of the two hydrogen atoms, it would not have acquired a negative charge, since the electrons would be more evenly distributed. In the proper structure, the electrons have amalgamated towards the sulfur, leaving the hydrogens to acquire a slight positive charge. (And positive and negative charges are very strong). 

[noob_]

thank you for answering the first part.
Can i just inquire though, if i did draw it as H-S-H in an exam or test, would i be wrong? Is there anyway to determine the shape of a valence structure?
I thought it was just that you divide 360 by the number of pairs of electrons around the central atom.
Eg: 2 pairs = 180 degree difference between atoms
3 pairs = 120 degree difference e.t.c

[AWK]

Also why is it BF3
And not BF5?
Boron has 3 valence electrons and needs additional 5 for stable outershell
Fluorine has 7 valence electrons and needs 1 electron for stable outershell
BF3 means that Boron will gain an additional 3 electrons, totaling 6 valence in it's outershell and not 8?
Edit #2: I just realised why it isnt BF5, B only has 3 outershell electrons -_-..
But i still don't get how the bond BF3 is made, only Fluorine has the complete outershell in this case?
Or BF3 like an emperical formula?

In covalent bond each atoms gives 1 electron - hence BF3.
In coordination bond ligand gives 2 electrons - hence BF4^-

[noob_]

Thank AWK.
But what i DONT understand is that in BF3, Boron is still 2 electrons away from a complete outershell.
Also,
is BeH2 a covalent bond or ionic bond, it is metal and non-metal meaning it should be ionic and Be has a 2+ charge whilst H has a 1- charge, yet i've been told that BeH2 is the result of a covalent bond? How is this possible..I did not know that rules could be broken in chemistry, i've always assumed it was like maths, either right or wrong..

[poisonkiller]

Thank AWK.
But what i DONT understand is that in BF3, Boron is still 2 electrons away from a complete outershell.

Think, does boron add or give away electrons?

Also,
is BeH2 a covalent bond or ionic bond, it is metal and non-metal meaning it should be ionic and Be has a 2+ charge whilst H has a 1- charge, yet i've been told that BeH2 is the result of a covalent bond?

Find out what makes a covalent bond different from an ionic bond.

How is this possible..I did not know that rules could be broken in chemistry, i've always assumed it was like maths, either right or wrong..

At one point I thought so too. But when I learned about things like metals reacting with nitric acid and what the products are, and it totally confused me. So I just accepted the fact, that at the moment not everything can be right or wrong. A lot of things can, but some cannot.

[cliverlong]

Bond pair Electron repulsion is a good predictpr of molecule shape

http://www.chemguide.co.uk/atoms/bonding/shapes.html

BF3 has a trigonal shape

http://winter.group.shef.ac.uk/vsepr/BF3.html

Bonds are neither wholly covalent nor ionic

http://www.chemguide.co.uk/atoms/bonding/electroneg.html#top