1. Atom Basic Component of Matter

2. Electrons Negatively charged particles

3. Nucleus Tiny, massive core containing protons and neutrons

4. Protons Positively charged particles in an atom’s nucleus Made of 3 quarks

5. Energy Level Specific amount of energy an electron has

6. Neutron Particles in the nucleus of an atom that has no electric charge

7. Atomic Number Number of protons in nucleus of an atom

8. Isotopes Atoms of the same element but have a different amount of neutrons

9. Mass Number The sum of the protons and neutrons in the nucleus. Note: a whole number because it refers to specific atom.

10. Atomic Mass Average mass of all isotopes

11. Periodic Table Arrangement of elements showing repeating pattern of elements

12. Periods Horizontal rows in the periodic table

13. Groups Vertical columns of the periodic table

14. Chemical Symbol Symbol of an element using letters

15. Metals An element that is a conductor of heat

16. Malleable Material that can be hammered, rolled into flat sheets, or shaped

17. Ductile Material that can be pulled out into a long wire

18. Thermal Conductivity Ability of an object to transfer heat

19. Electrical Conductivity Ability of an object to transfer electricity

20. Reactivity The speed which a substance reacts with other substances

21. Corrosion Gradual wearing wearing of a metal because of chemical reaction

22. Alkali Metals Metals in group one of the periodic table

23. Alkaline Earth Metals Group two of the periodic table

24. Transition Metals Elements in group three to group twelve on the periodic table

25. Particle Accelerators Powerful machines that move atomic nuclei really fast

26. Nonmetal Elements that lack most properties of metal

27. Diatomic Molecule Molecule that consists of two atoms

28. Halogens Group 17 of the periodic table

29. Inert Gases Group 18 of the periodic table

30. Semimetals Elements that have some metal and have some properties that are nonmetal

31. Semiconductors Substances that can conduct an electric current under some circumstances and cannot in some circumstances

32. Radioactive Decay Atomic nuclei of isotopes release fast-moving particles and energy

33. Radioactivity Property that is able to emit radiation

34. Alpha Particle Consists of two neutrons and two protons and is positively charged

35. Beta Particle Fast moving electron that is given off by a nucleus during radioactive decay

36. Gamma Radiation High energy waves

37. Tracers Radioactive isotopes that can be followed using a detector

38. Molecule Two or more atoms joined in chem. bond

39. Compound A pure substance made of two or more elements chemically combined