The atom with eight protons in its nucleus (atomic number 8 ... the next electron goes into the fourth level. 4th Period: Potassium and Calcium—Electrons go into the fourth energy level. A small piece ...

For example, the mass number of argon atoms and calcium atoms can both be 40. The atomic number of a chlorine atom is 17 and its mass number is 35. Calculate the number of protons, neutrons and ...

The positive and negative ions attract each other and form the ionic compound sodium chloride. One calcium and two chlorine atoms are near each other. An electron from each atom feels the attraction ...