What is a line spectrum?

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.

Which type of intermolecular attractions holds ammonia molecules together with other ammonia molecules?

Why do electrons further from the nucleus have more energy