atomic structure

2. the force that causes one object to push another object away from itself.
3. an electric charge developed when an object contains more protons than electrons.
6. the center or middle.
7. moving in only one direction.
9. one polarity of a voltage, current, or charge that has an excess of electrons.
12. one of the three principal parts of an atom. Has a positive charge.
14. current that reverses its direction of flow periodically. Reversals generally occur at regular intervals.
16. a material used to electrically isolate two conductive surfaces.
17. a material that contains four valence electrons and is used in the production of solid-state devices.
19. one of the principal parts of an atom. Has no charge and is part of the nucleus.
21. the smallest part of an element that contains all the properties of that element.
22. the smallest part of a compound that is made of individual atoms.

1. current that does not reverse its direction of flow.
4. electrons located in the outer orbit of an atom.
5. the shell in which an electron moves around the nucleus of an atom.
8. This number is equal to the number of protons (positively charged particles) in the nucleus of an atom.
10. the force that causes one object to pull another object to itself.
11. anything that occupies space.
13. an object that moves in two directions.
15. one of the three major parts of an atom. Carries a negative charge.
18. a device or material that permits current to flow through it easily.
20. (1) one of the basic building blocks of nature. An atom is the smallest part of this; (2) one part of a group of devices.