How many protons, neutrons, and electrons are in a neutral atom of sodium?
The subatomic particles (protons, neutrons and electrons) can be determined using some basic information from the periodic table.
The element Sodium has an atomic number of 11 and an average atomic mass of 22.98 which makes the mass number 23.
An atomic number of 11 means this atom will have 11 protons.
A mass number of 23 means 23 - 11 this atom will have 12 neutrons.
Since this atom is neutral the positive protons must be equal to the negative electrons. This atom will have 11 electrons.