EXAM 1: Material of the Universe

1. When physical or chemical changes occur___________the ability to do work or to transfer heat is absorbed or released.

2. _________ exists in three main physical states: Gas, Liquid or Solid

3. Protons, neutrons and electrons are:

4. The atomic number, element symbol and mass number are all:

5. Atoms of the same element that differ in mass are known as:

6. Atoms can combine to form ________. Both atoms and molecules can gain or lose electrons, resulting in electrically charged particles called ______-

7. Which model described atoms as small, spherical indivisible particles?

8. Which model described the atom as consisting of smaller subatomic particles?

9. Which model stated that the atom is mostly empty space?

10. Which model proposed that an atom's electrons could travel only in certain larger orbits around the nucleus?

11. The fixed energy levels in the quantum mechanical model are called:

12. Electrons are said to travel in ______ instead of clearly defined orbits.

13. _________ describes the distribution of electrons among the atom's orbitals.