Question

The atomic number and mass number of sodium are 11 and 23 respectively. What information is conveyed by this statement?

Answer 1

The atomic number is the number of protons present in the sodium atom and so the number of protons in sodium are 11.
The number of electrons equal the number of protons in a neutral atom. Number of electrons is 11.
The number of neutrons = Mass number -atomic number = 23-11 = 12.