[natalieee (OP)]

um so i need some help for chemistry as my teacher is away all week. PLEASE if you can help me as i also have a test on thursday.

who can explain electron shells to me?
also ions and the ionic compound forming method?

and is the ion for ammonia NH4 r NH3
(the 4 and 3 being little under the H)

thank you.

[blakestyger]

The whole business of electron shells is too big to explain here but should be accessible in any basic textbook or you could Google it - though I couldn't find anything suitable.

Bubble ammonia (NH3) through water (H2O) and you'll get some ammonium hydroxide - that is, two ions, ammonium and hydroxyl, though the latter will have a water molecule bonded to make it a hydroxonium ion (H₃O⁺)

NH₃ + H₂O → NH₄⁺ + OH^-

[Bored chemist]

That reaction goes in the oposite direction. Ammonium hydroxide has no real existence; it would instantly decompose to ammonia and water.
Ammonia is NH3
The ammonium ion is NH4+