Fill in the Blanks AtomsOnline version The number of protons in the nucleus of the atom is equal to the atomic number. The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom and the atomic number. by A Hoog 1 Carbon Atomic Number : 6 Number of Protons : Number of Neutrons : Mass Number : 12 Oxygen Atomic Number : Number of Protons : 8 Number of Neutrons : 8 Mass Number : Hydrogen Atomic Number : 1 Number of Protons : Number of Neutrons : Mass Number : 1 Carbon Atomic Number : Number of Protons : 6 Number of Neutrons : Mass Number : 14 Hydrogen Atomic Number : 1 Number of Protons : Number of Neutrons : 2 Mass Number : Nitrogen Atomic Number : Number of Protons : Number of Neutrons : 7 Mass Number : 14 Hydrogen Atomic Number : Number of Protons : Number of Neutrons : 1 Mass Number : 2