UNIT 1 KEY TERMS

3. anything that occupies space.
5. Orbit the shell in which an electron moves around the nucleus of an atom.
6. Current (DC) current that does not reverse its direction of flow.
8. Electrons electrons located in the outer orbit of an atom.
10. one of the three major parts of an atom. Carries a negative charge.
13. one of the basic building blocks of nature. An atom is the smallest part of this; (2) one part of a group of devices.
14. the force that causes one object to pull another object to itself.
16. moving in only one direction.
17. the center or middle.
18. one of the principal parts of an atom. Has no charge and is part of the nucleus.
19. an object that moves in two directions.
21. one of the three principal parts of an atom. Has a positive charge.
22. Number This number is equal to the number of protons (positively charged particles) in the nucleus of an atom.

1. an electric charge developed when an object contains more protons than electrons.
2. one polarity of a voltage, current, or charge that has an excess of electrons.
4. the smallest part of a compound that is made of individual atoms.
7. a material used to electrically isolate two conductive surfaces.
9. Current (AC) current that reverses its direction of flow periodically. Reversals generally occur at regular intervals.
11. a material that contains four valence electrons and is used in the production of solid-state devices.
12. the smallest part of an element that contains all the properties of that element.
15. a device or material that permits current to flow through it easily.
20. the force that causes one object to push another object away from itself.