1. Periodic Trends Chapter 5 Part 2

2. Atomic Radius  The definition of the radius of an atom is 90 % of the electron density.

3. Atomic Radius  The radius of the atom decreases with each increase in the atomic number.  Why?  The pull of the increased atomic number attracts the electrons closer to the nucleus.

4. Ionization Energy  The ionization energy is the amount of energy it takes to detach one electron from a neutral atom.

6. Electron Affinity  The energy change with the addition of an electron.

7. Electronegativity

8. Summary

9. Groups and Periods  We learned about groups, the columns, and periods, the rows.  Now we will examine the trends seen in each group.

10. Group IA: Alkali Metals  Known as Alkali Metals  Very reactive  Never found free in nature  React readily with water

11. Group IIA: Alkaline Earth Metals  Known as Alkaline earth elements  All are metals  Occur only in compounds in nature.

12. Group IIIA  Metalloids  Includes Aluminum  (the most abundant metal in the earth)

13. Group IVA  Includes metals and nonmetals  Go from nonmetals at the top of the column to metals at the bottom

14. Group VA

16. Group VIIA: Halogens  As a group, the most electronegative.  Gains one electron to have a noble gas like electron configuration.  Called halogens, which mean "salt forming"  Are all highly reactive

17. Group VIIIA: Noble Gases  Least reactive group  All elements are gases  Not very abundant on earth  Given the name noble gas because they are not very reactive

18. Metalloids  Elements that touch the stair case have both metal and non metal characteristics.  They are called semi- metals or metalloids.

19. Transitional Metals  These elements have valence electrons in the d orbital.