1. Ions Ion – an atom with a positive or negative charge.
When atoms gain or lose electrons they become ions.

2. A positive ion is called a cation.
A negative ion is called an anion.

5. Valence Electrons and the Periodic Table
Group 1 – All have 1 valence e-
Group 2 – All have 2 valence e-
Group 13 – All have 3 valence e-
Group 14 – All have 4 valence e-
Group 15 – All have 5 valence e-
Group 16 – All have 6 valence e-
Group 17 – All have 7 valence e-
Group 18 – All have 8 valence e-

7. Cations How does an atom become a cation?
To become a cation, an atom loses an electron(or electrons) to have a complete outer shell. Now it has more positive charges than negative charges and is positively charged.
Na --- Na e-

8. Another
Magnesium – to the board….

9. Anion How does an atom become an anion?
To become an anion, an atom gains an electron(or electrons) to have a complete outer shell. Now it has more negative charges than positive charges and is negatively charged.

10. Ion Charges and the Periodic Table
Group 1 – forms ions with a 1+ charge
Group 2 – forms ions with a 2+ charge
Group 13 – forms ions with a 3+ charge
Group 15 – forms ions with a 3- charge
Group 16 – forms ions with a 2- charge
Group 17 – forms ions with a 1- charge
Metals always form positive ions(cations), they lose electrons.
Nonmetals always form negative ions(anions), they gain electrons.

11. How many protons and electron in the following ions:
A. F-
B. Cu2+
C. Sr+
D. Ni2+
E. As3-

12. For each of the following atomic numbers, use the periodic table to write the chemical formula for the ion that the element is most likely to form:
a. 16 b. 20 c. 37 d e. 15

13. Warm-Up
#1: Give the number of valence electrons in each of the following elements:
a. magnesium
b. boron
c. bromine
d. neon

14. #2: Indicated the number of protons and electrons in the following ions:
A. O2-
B. Fe3+
C. Li+
D. Ba+
E. F-

15. #3.For each of the following atomic numbers, use the periodic table to write the chemical formula for the ion that the element is most likely to form:
a. 4 b. 34 c. 37 d e. 7

16. #4. Cations have a __________________ charge because they have fewer ______________ than protons.

17. Periodicity
In the context of chemistry and the periodic table, periodicity refers to trends or recurring variations in element properties with increasing atomic number. 
Periodicity is caused by regular and predictable variations in element atomic structure.

18. Atomic Radius
The size of atoms get larger going down a group on the periodic table.
Size gets small going from left to right.

19. Why would an element on the left of period, example lithium which has 3 electrons, have a bigger radii than neon on the right side which has 10 electrons?
As the number of protons increases so does the positive charge of the nucleus. That charge tends to pull the valence electrons closer to the nucleus.

20. Ionization Energy
The energy required to remove a valence electron from a particular element.

21. Why do the metallic elements of a given period have relatively low ionization energies than do the nonmetallic elements of the same period?
The element of a given period have valence electrons in the same energy shell but nuclear charge increases going left to right. Atoms on the left have smaller nuclear charges and hold on to their electrons less tightly.

22. Ionic Radii

24. Electronegativity
The tendency of an atom in a compound to attract electrons to itself.

28. Why are there no electronegativity values for the Noble Gases?
The Noble Gases are not assigned electronegativity values because they tend not to gain or lose valence electrons because they have complete octets(8 valence electrons).

29. Reactivity of the Alkali Metals

30. Atoms and Their Electrons