1. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 Ch. 6 Vocabulary – Introduction to Atoms (p. 183, 11 terms + 4)

2. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 1. Atom The smallest unit of an element that maintains the properties of that element.

3. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 2. Electron A subatomic particle that has a negative charge.

4. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 3. Nucleus In physical science, an atom ’ s central region, which is made up of protons and neutrons.

5. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 4. Electron Cloud A region around the nucleus of an atom where electrons are likely to be found.

6. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 5. Proton A subatomic particle that has a positive charge and that is located in the nucleus of an atom; the number of protons in the nucleus is the atomic number, which determines the identity of an element.

7. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 6. Atomic Mass Unit A unit of mass that describes the mass of an atom or molecule.

8. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 7. Neutron A subatomic particle that has no charge and that is located in the nucleus of an atom.

9. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 8. Atomic Number The number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element.

10. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 9. Isotope An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass).

11. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 10. Mass Number The sum of the numbers of protons and neutrons in the nucleus of an atom.

12. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 11. Atomic Mass The mass of an atom expressed in atomic mass units.

13. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 12. Subatomic Particles Protons, neutrons, and electrons are much smaller than an atom.

14. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 13. Ion A charged particle that forms when an atom or group of atoms gains or loses one or more electrons.

15. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 14. Radioactive An unstable atom (isotope) with a nucleus that changes over time. Over time, they fall apart, giving off smaller particles and energy.

16. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 15. Force A push or pull exerted on an object in order to change the motion of the object; force has size and direction.

17. Unit 3 (Ch. 6) - Atom/Periodic Table Bach 11/24/09 Grading Scale (1 point per term) A = 15 - 14 B = 13 - 12 C = 11 D = 10 - 9 F = 8 or less