Chapter 10 Vocab

2. A negatively charged particle that moves around the nucleus of an atom; narrow rays of electrons create a picture on a TV screen.
4. Particle with no charge, 1800 times the mass of an electron; located in the nucleus of an atom.
6. An element with five or more electrons in the outer energy level; a poor conduction of heat and electricity; tends to gain electrons when it reacts with metals.
8. The average of the atomic masses of the naturally occurring isotopes that make up an element.
12. An arrangement of the chemical elements in rows according to increasing atomic numbers, in vertical columns having similar properties.
14. Region around the nucleus occupied by electrons.
16. An element that has properties of both metals and nonmetals; B, Si, Ge, As, Sb, Te, Po, At.
18. The horizontal rows of the periodic table.
19. Elements in Group 18 on the periodic table, all except helium have eight electrons in their outer energy level; member elements are stable and occur as single atoms in nature.
20. A positively charged particle in the nucleus of an atom.

1. The number of protons in the nucleus of an atom.
3. The elements in Groups 3 through 12 on the periodic table; usually have two electrons in the outer energy level; include some familiar metals.
5. Elements whose atoms generally have three or fewer electrons in their outer energy level; are shiny, conduct heat and electric current tend to lose electrons in reactions.
7. The smallest unit of an element that retains the properties of that element.
9. A vertical column in the periodic table; elements within a group have similar chemical properties.
10. The ease with which an element reacts with other elements.
11. Element in Group 17 on the periodic table; reactive nonmetals, each with seven electron in its out energy level.
13. The central portion of an atom containing neutrons and protons.
15. The sum of protons and neutrons in an atom.
17. Atoms of the same element with different numbers of neutrons.