The negative (oxygen) end of water is attracted to the positive sodium ion in the salt, extracts it from the lattice and more water molecules surround it (i.e. dissolve it). The same is true for the positive (hydrogen) end of water and the negative chloride ion in the salt.
According to nitrogen's electron configuration table, an atom of nitrogen contains two electrons in its first energy level (both in the s sub-shell) and five electrons in its second energy level (two in the s sub-shell and three in the p sub-shell). A more accurate Bohr model of a nitrogen atom could look like this: In the refined Bohr model, a nitrogen atom has a central nucleus, composed of seven protons and seven neutrons, surrounded by seven electrons.
The atomic mass for an atom of hydrogen is one dalton, which is calculated from the lone proton. Remember, electrons are too small to be considered in the atomic mass. Helium is the second lightest element, and is larger than hydrogen. It consists of two protons and two neutrons. Because protons and neutrons are approximately the same size, the atomic mass of a helium atom is four daltons. Let's look at a larger atom. Barium has an atomic mass of 137 daltons.