I am learning the basics of bonding and reading about valence and lone electron pairs. I am confused on why nitrogen would bond 4 atoms of hydrogen such as in ammonium chloride. To me nitrogen has a valence of 3 so it can only form 3 bonds yet in NH4Cl it forms 4 bonds. Why would this be? Is this a concept of electronegativity? Furthermore in my book it states that the ions of NH4Cl are NH4+ and Cl-. Obviously the NH4+ has a positive charge but is this because it gives one electron to the Cl atom in the bond NH4Cl? Very basic but trying to grasp concepts.
When NH4Cl is in water, what pulls these two apart to create the cation NH4+ and Cl-? Are the bonds that these form with water stronger than the bonds between the NH4 and Cl so much so to pull them apart?