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 ...

An atomic number – the number of protons in the nucleus of an atom of the element. These rules help in identifying and ...

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 ...