in this video we'll look at the difference between ammonia and the ammonium ion so first off ammonia that's a molecule NH3 it's neutral doesn't have a charge doesn't have a plus or a minus after it so ammonia neutral molecule the ammonium ion it's an ion we say it's an ion it has this positive charge this one plus ionic charge so that's one of the big differences the next thing is the formula is different we have three hydrogens here and four here a big notable difference is ammonia has a very strong odor the ammonium ion that's odorless if we count up the valence electrons nitrogen has five hydrogen has one but we have three hydrogens we'd have eight valence electrons for ammonia for the ammonium ion 5 + 1 * 4 and that positive charge that means an electron has been lost so we subtract one 5 + 4 is 9 - 1 still8 so they have the same number of veence electrons if we look at the leis structure for each one we can see those eight valence electrons they're distributed around that Central nitrogen for the ammonium we put brackets around it and a positive sign to show it's an ion we don't need to do that for ammonia since that's a neutral compound when you look at the structures you'll see these two electrons here these are called unbonded electrons so ammonia has two unbonded electrons called a lone pair we don't have any lone pairs on the ammonium ion that affects the structure the molecular geometry and bond angles for ammonia and the ammonium ion let's take a look at that for ammonia we have that lone pair there and that's pushing down each one of those hydrogen atoms so we end up with what's called a trigonal parameter molecular geometry kind of like a pyramid with those lone pair of electrons on the top if we look at the ammonium ion we have those four hydrogens attached to the central nitrogen we end up with a different molecular geometry this molecular geometry is called tetrahedral let's go back to our leis structures so now that we know the shape we can draw our leis structure a little bit differently here the lines represent a pair of electrons shared between atoms and you see the trigonal paramal molecular geometry for the ammonia the ammonium ion that has that tetrahedral molecular geometry these Bond angles right here are about 107° over here we have about 109.5° if you are asked to get a sample of ammonia you could get ammonia gas which just be NH3 there's also liquid ammonia if you cool it enough the ammonium ion doesn't really exist by itself it's always bonded to something like a chlorine we'd have ammonium chloride or it could be dissolved in water surrounded by water molecules aquous so that is another big difference between ammonia and the ammonium ion this is Dr B discussing the difference between ammonia and the ammonium ion we have NH3 and nh4 plus there are links in the description to more information about Bond angle molecular geometry Lewis structures and hybridization thanks for watching