An atom has an atomic number of 19 and a mass number of 39. How many electron ,protons and neutrons does it have?
(a) Describe the Rutherford's model of an atom. State one drawback of Rutherford's model of the atom.
(b) The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?