Name __________________________________ Hour_____ Date____________________
Trends WS
1. As the atomic number increases across a row in the periodic table, does the
Valence electron – nucleus attraction increase or decrease?
2. Using your answer to the valence electron – nucleus attraction in question 1, explain why
(a) atomic radius decreases across a period?
(b) ionization energy increases across a period?
3. In going from hydrogen to helium, what do the changes in atomic radius (37 to 32 pm) and ionization energy
(1311 kJ/mole to 2377 kJ/mole) suggest about the relative magnitudes of the change in the electron – nucleus
attraction? Why?
4. What happens to the atomic radii and ionization energies in going down a group, e.g., from Ne to Xe or Li to
Rb? How are they related?
5. Atoms with large atomic radii tend to form positive ions. Why?
6. Peaks in ionization energy occur at atomic numbers equal to 10, 18, 36, and 54, but these elements have very
small or zero electron affinities. Peaks in the electron affinity occur at atomic numbers equal to 9, 17, 35, and
53. Why does an increase of 1 for the atomic number in each period, result in such a drastic change in electron
affinity?
7. Identify the atom with the largest atomic radius for each pair and then explain why that one is larger.
oxygen or sulfur
calcium or potassium
8. Select the atom in each pair that has the greater electron affinity and explain why.
C or O
Cl or Br
9. Name the element identified.
a. Most massive element in group 15
b. Least massive element in group 5
c. Most reactive non-metal in in group 16
d. Least reactive metal in group 2
e. Element in period two that exhibits the most shielding
f. Element in group 7 with the most shielding
g. Element in period 4 with an electron configuration ending in d10