.What is at the center of every atom?
2.What is the atomic symbol for the element cobalt?
3.What role does atomic number play in the periodic table?
4.Distinguish between atomic number and mass number?
5.If two protons and two neutrons are removed from the nucleus of an oxygen-16 atom, a nucleus of which element remains?
6.If an atom has 43 electrons, 56 neutrons, and 43 protons, what is its approximate atomic mass? What is the name of this element?