Which of the following has the largest % of sodium, 20g of sodium fluoride, 20g of sodium chloride, or 20g of sodium bromide?

Which of the following statements is true? a. elements in the last period are radioactive. b. atomic weight is the same as atomic mass. c. elements in the same group have the same number of electron shells. d. atomic number equals the number of neutrons in the nucleus of an atom.

Word equation for k(s) +h2o(l) yield koh (aq) + h2

How many valence electrons are in atom of radon?