Hence atomic number = 18 Number of protons + neutrons ... be shown as a list of numbers or as a diagram. Take lithium for example. The diagram above shows each shell as a circle around the ...

Elements are arranged in the periodic table in order of increasing atomic number. For example hydrogen has the atomic number of one, helium two, lithium three etc. The first energy level (the one ...

For example, a helium atom has an atomic mass of 4, but an atomic number (or positive charge) of 2. Since electrons have almost no mass, it seemed that something besides the protons in the nucleus ...