Sulfur (S) has the atomic number 16, how many protons are in the nucleus of a sulfur atom?
Sodium (Na) has 11 protons, 11 neutrons and 11 electrons, what is the approximate atomic mass of a sodium atom?
Magnesium (Mg) has 12 protons, 12 neutrons and 12 electrons, what is the atomic number of magnesium?