MODERN PERIODIC TABLE

3. Horizontal rows in the periodic table.
6. Elements in Groups 3–12; also known as transition ______.
7. Group of elements containing fluorine, chlorine, bromine, iodine, and astatine.
8. The element in Group 1 that reacts violently with water.
11. The scientist who arranged elements in octaves.
14. Shells The period number represents the number of these energy levels.
15. The scientist who arranged elements in triads.
17. The group known as the salt formers.
20. Earth Elements in Group 2; also called alkaline earth metals.
21. Elements that are dull, brittle, and poor conductors of heat and electricity.
23. Gases Elements in Group 18; very stable and unreactive gases.

1. The element that is a nonmetal but placed with Group 1 because of its single electron.
2. Periodic Law The law stating that properties of elements are periodic functions of their atomic numbers.
4. Elements in Group 1; very reactive metals.
5. The scientist who arranged elements by increasing atomic number.
9. Elements that are shiny, malleable, and good conductors of heat and electricity.
10. The Russian chemist who created the first periodic table.
12. The most abundant gas in Earth’s atmosphere, found in Group 15.
13. Elements with properties of both metals and nonmetals.
16. The element symbol for calcium, found in Group 2.
17. The element symbol for the lightest noble gas.
18. Vertical columns in the periodic table.
19. Scientist who discovered the concept of atomic number through X-ray experiments.
22. Number The number of protons in an atom, used to arrange elements in the modern periodic table.