You land on a distant planet in another universe and find that the n = 1 level can hold a maximum of 4 electrons, the n = 2 level can hold a maximum of 5 electrons, and the n = 3 level can hold a maximum of 3 electrons. Like our universe, protons have a charge of +1, electrons have a charge of 1, and opposite charges attract. Also, a filled shell results in greater stability of an atom, so the atom tends to gain or lose electrons to give a filled shell. Predict the formula of a compound that results from the reaction of a neutral metal atom X, which has 7 electrons, and a neutral nonmetal atom Y, which has 3 electrons.