Joan and mike's teacher show them a picture of an atom and ask them to identify it using the periodic table. joan says the atom is carbon, but mike says it is lithium. who is right and why? a joan is correct because carbon is a neutral atom. there are the same number of protons and electrons in the atom pictured. b mike is right because the atomic mass of lithium is 6. there are 3 protons and 3 electrons in the atom. 3+3=6 c mike is correct because the atomic number shows the number of protons in all atoms. there are 3 protons and the atomic number of lithium is 3. d joan is right because the atomic number of carbon is 6. there are 3 protons and 3 electrons in the atom. the atomic number shows the number of protons plus the number of electrons. 3+3=6