Unit 1.7

Question 1

Factors Influencing Periodic Trends (3)

Answer 1

1. Electron Energy Level
2. Effective Nuclear Charge
3. Shielding Effect

Question 2

Electron Energy Level

Answer 2

Distance from the nucleus.

INCREASES down.

Question 3

Effective Nuclear Charge

Answer 3

The number of protons influences the pull on the electrons.

INCREASES across.

Question 4

Shielding Effect

Answer 4

Valence electrons are “shielded” from the pull/charge of the nucleus by all the electrons in between.

INCREASES down.

Question 5

Atomic Radius

Answer 5

Half the distance between nuclei of two atoms of the same element (a.k.a. Atomic Size).

INCREASES down ~ Energy Levels ↑
DECREASES across ~ Nuclear Charge ↑

Question 6

Ionic Radius

Answer 6

Half the distance between nuclei of two ions.

INCREASES down ~ Energy Levels ↑
DECREASES across* ~ Nuclear Charge ↑

*Decreases across RELATIVE TO NORMAL SIZE. Remember: cations are smaller than Anions; anions have more electrons, so nuclear charge is not as strong.

Question 7

Ionization Energy

Answer 7

Amount of energy required to remove a valence electron from an atom.

DECREASES down ~ Shielding Effect ↑
INCREASES across ~ Nuclear Charge ↑

Question 8

How do you use an Ionization Energy chart to determine how many valence electrons an element has?

Answer 8

There is a significant “jump” after the atom reaches “Noble Gas Formation”.