1. Click on start to begin the animation. You will see a periodic table partially filled. Look at the atomic size of the elements and indicate, in the periodic table below, all the trends you see. Check your reasoning with the TA.

2. Place the remaining elements in the periodic table according to the patterns found in question 1.

3. Look at the common ions of the elements in the periodic table.
1. Why is chlorine ion bigger than the neutral species? Explain your answer (hint: electrons repel each other because they have the same charge).

2. Why is sodium ion smaller than the neutral species? Explain your answer.

4. Identify the ionization pattern of groups 1A and 2A.

1A	Ion	2A	Trend explanation: ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Ion
Li		Be
Na		Mg
K		Ca
Rb		Sr
Cs		Ba
Fr		Ra

5. Identify the ionization patterns of ups 5A, 6A, and 7A. .

Trend explanation: _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

5A	Ion	6A	Ion	7A	Ion
N		O		F
P		S		Cl
		Se		Br
				I

6. In the previous activity you observed a pattern for the formation of ions. In this exercise, we want you to begin to understand the reason for the pattern.

1. What do Na⁺, F^-, and Ne have in common? Explain your answer (hint: think in terms of electrons).

2. What do P^3-, Cl^-, Ca²⁺, and Ar have in common? Explain your answer.

7. Based on the animation and your previous responses, answer the following questions.
1. Which groups of elements donate electrons more easily? Would the ionization energy be high or low for these groups? Explain your answer.

2. Which groups of elements receive electrons more easily? Would the ionization energy be high or low for these groups? Explain your answer.

3. For each of the following pairs indicate which atom will have the larger first ionization. Explain your reasoning.

Explanation: _______________________________________________________________________________________________________________________________________________________________________________________________________________________

O	Ne
Mg	Sr
Cs	La
Br	Sb
Si	N

4. Mg atoms are lager than O atoms. Explain why Mg²⁺ ions are smaller than S^2- ions. Which element should have the largest ionization energy?

8. Explain why the electron affinity of F is a negative value whereas the electron affinity is a positive value (hint: remember that when the electron affinity is a positive number the ion will not form).

9. Explain in your own words the similarities and differences between ionization energy and electron affinity. Donºt forget to include periodic trends.