Across
- 2. the horizontal rows of the periodic table
- 4. the number of protons in the nucleus of an atom
- 7. an element that has properties of both metals and nonmetals
- 8. a positively charged particle in the nucleus of an Atom
- 10. the average of the atomic masses of the naturally occurring isotopes that makeup an element
- 11. 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
- 13. elements in Group 18 on the periodic table; all except helium have 8 electrons in their outer energy level; member elements are stable and occur as single atoms in nature
- 16. and arrangement of chemical elements in rows according to increasing atomic numbers, in the vertical columns having similar properties
- 18. particle with no charge; 1800 times the mass of an electron; located in the nucleus of an atom
- 19. the sum of protons and neutrons in an atom
Down
- 1. the central portion of an atom containing neutrons and protons
- 3. region around the nucleus occupied by electrons
- 5. the ease with which an element reacts with other elements
- 6. atoms of the same element with different numbers of neutrons
- 9. the elements in groups 3 through 12 on the periodic table: usually have two electrons in the outer energy level; include some familiar metals
- 12. elements in Group 17 on the periodic table; reactive nonmetals, each with seven electrons in its outer energy level
- 14. the smallest unit of an element that retains the properties of that element
- 15. vertical column in the periodic table; elements within a group have similar chemical properties
- 17. an element with five or more electrons in the outer energy level; a poor conductor of heat and electricity; tends to gain electrons when it reacts with metals
- 20. a negatively charged particle that moves around the nucleus of an atom; narrow rays of electrons create a picture on a tv screen