Periodic History

4. A metal that is shiny and that conducts heat and electricity well.
6. One of the element of Group 18 of the Periodic Table.
10. A table of the chemical elements arranged in order of atomic number, usually in rows, so that elements with similar atomic structure appear in vertical columns.
11. An atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge.
13. The quantitative measure, usually given in electron-volts, of the tendency of an atom or molecule to capture an electron and to form a negative ion.
15. A negatively charged ion.
17. Any element in any of the series of elements with atomic numbers 21–29, 39–47, 57–79, and 89–107, that in a given inner orbital has less than a full quota of electrons.
19. A member of the rare-earth series of elements, whose atomic numbers range from 58 to 71.
20. An element that has properties of both metals and nonmetals.

1. Any of the series of heavy radioactive elements that extends from thorium through lawrencium on the periodic table.
2. The chemical and physical properties of the elements recur periodically when the elements are arranged in the order of their atomic weights.
3. The quality that determines the number of atoms or groups with which any single atom or group will unite chemically.
5. A measure of the ability of an atom in a chemical compound to attract electrons.
7. The energy required to remove an electron from an atom or ion.
8. An element in the s-block or p-block or the periodic table.
9. A positively charged ion.
12. An element that conducts heat and electricity poorly and that does not form positive ions in an electrolytic solution.
14. A substance made up of atoms of two or more different elements joined by chemical bonds.
16. The distance from the atomic nucleus to the outermost stable electron orbital in a atom at equilibrium.
18. To separate or change ions.