1. Nucleus
The central core of an atom. The nucleus contains two types of particles, positively charged protons and (usually) neutral neutrons

2. Electron
A tiny negatively charged particle that moves around the nucleus of an atom.

3. Electron Cloud Model
Model of an atom with a nucleus and electrons that move around the nucleus in unpredictable patterns. The cloud is where the electron might be at any moment.

4. Valence Electrons
The electrons in the outermost energy level of an atom. These are the electrons that are available to bond with other atoms.

5. Atomic Number
The number of protons in an atoms nucleus. This is equal to the number of electrons in the atom

6. Maleable
A Maleable substance is one that can be pounded or bent into shapes

7. Ductile
A ductile substance is one that can be pulled or stretched into wire

8. Conductors
A conductor allows heat and electricity to pass through it easily. Metals are often very good conductors.

9. Reactivity
The ease and speed with which one substance forms chemical bonds with another.
Reactive elements form bonds easily, non-reacitve elements do not.

10. Alkali Metal
An element in group 1 of the periodic table. -HIGHLY reactive -gray and shiny -soft enough to cut with a butter knife.
Alkali Metal Reacting with Water

11. Alkaline Earth Metals An element in group 2 of the periodic table.
-silvery or bright white
-slightly harder than alkali metals
-VERY reactive, although not quite as reactive as Alkali

12. Transition Metals
Any element between group 3 and group 12 of the periodic table
-Hard and Shiny
-Often gray but can be yellow, orange, etc
-Bond with lots of other elements

13. Metalloid
Has some characteristics of metals and some of non metals. Many are semi-conductors Examples = silicon, boron, and arsenic

14. Semi-Conductor
An element that can conduct electricity under certain conditions. Used to make computer chips and lasers. Example - silicon

15. Carbon Family
Group 14 of the periodic table, contains metals, nonmetals, and metalloids. 4 valence electrons

16. Halogens
Group 17 on the periodic table, almost all non metals, many members are gases, highly reactive, 7 valence electrons

17. Noble Gases
Group 18 on the periodic table. All gasses, very UNreactive, 8 valence electrons