Unit 4 The Periodic Table

2. The modern periodic table is organized by increasing what?
4. Atom or group of atoms with a positive or negative charge
5. Energy needed to remove an electron from an atom in the gaseous state
8. F- and O2- are examples of this
9. Have properties of both metals and nonmetals
10. Na+ and Mg2+ are examples of this
13. These are found underground and can be dull
16. Ability of an atom of an element when in a compound to attract electrons
19. Most are gases. If a solid, it is usually brittle.
20. Father of the periodic table
21. Shiny, easily cut, and very reactive

1. 1/2 the distance between two nuclei of the same element when joined
3. Most of these don't exist naturally
6. An example of an element that has been known for thousands of years
7. The most electronegative element
11. When elements are arranged in order of increasing atomic number, there is a repetition of physical and chemical properties
12. Generally good conductors of heat and electricity
14. Inert and have a full outer electron shell
15. The first periodic table was organized by what?
17. Found in the d block and used in a variety of ways
18. Most reactive nonmetal group