Chapter 10

4. The number of protons and neutrons in the nucleas of an atom
6. The sum of protons and and neutrons in an atom
9. A negatively charged particle that moves around the nucleus of an atom
11. Atoms of the same element with different numbers of neutrons
13. Region around the nucleus occupied by electrons
14. the ease in which an elemnt reacts with other elements
16. Particle with no charge
17. An element with 5 or more electrons in the outer energy level; poor conducter of heat and electricity
18. An element that has properties of both metals and nonmetals; B,Si,Ge,As,Sb,Te,Po,At

1. The smallest unit of an element that retains the properties of that element
2. A positively charged particle in the nucleus of an atom
3. The horizontal rows of the periodic table
4. The average of the atomic masses of the naturally occuring isotopes that make up an element
5. Elements in group 17 on the periodic table; reactive nonmetals, each with seven electrons in its outer energy level
7. Elements in group 18; all except helium have 8 electrons in their outer energy level
8. A vertical column in the periodic table; elements within a group have similar chemical properties
10. The central portion of an atom containing neutrons and protrons
12. An arrangment of of the chemical elemnts in rows according to increasing atomic numbers, in vertical columns having similar properties
15. Elements whose atoms generally have three three or fewer electrons in their outer energy level; are shiny, conduct heatand electric current, tend to lose electrons in reactions