Unit 6 Periodic Trends (trends/application)

Question 1

Trend for atomic radii across a period

Answer 1

It decreases in size because there is a greater proton charge in the nucleus forcing the electrons to get closer to the nuclues

Question 2

Trend for atomic radii down a group

Answer 2

Increases in size because as energy levels increase outer electrons get farther from the nucleus and are held less tightly

Question 3

Trend for electron affinity across a period

Answer 3

a general increase (decreases among + ions; increases among -ions), more stable (greater energy charge) as ion approaches meeting octet rule.

Question 4

Trend for electron affinity down a group (- = energy is released)

Answer 4

a general decrease because as proton charge increases electron affinity and an increase in atomic radii that decreases electron affinities causes it.

Question 5

Trend for ionization energy across a period

Answer 5

Increases because of increasing proton charge that attracts electrons in the same energy level - it becomes harder to drop electrons as group 15-17 elements what to add electrons, not lose them.Noble gases don’t want to lose or gain anything.

Question 6

Trend for ionization energy down a group

Answer 6

Decreases because electrons down a group are in successively farther energy levels and held less tightly by the nucleus and due to electron shielding - as you go down it’s easier to remove an electron

Question 7

Trend for ionic radii across a period

Answer 7

It decreases thru group 3/13 major increase at group 4/14 then size decreases again because as atoms lose successive electrons, the proton charge is larger and condenses the electron cloud; major increase in size occurs as atoms gain electrons and then size decreases again due to increased proton charge

Question 8

Trend for ionic radii down a group

Answer 8

increase down a group because of more energy levels

Question 9

Trend for valence electrons across a period

Answer 9

Increases across a period because atoms are successively filling s and p orbitals - a larger valence shell

Question 10

Trend for valence electrons down a group

Answer 10

Stays the same; as # of energy levels increase the number of valence electrons stay the same (they are in the same group <– you know this :) )

Question 11

Trend for electronegativity across a period

Answer 11

Increases across a period because atoms have greater attraction for electrons as they move towards an attractive electron config

Question 12

Trend for electronegativity

Answer 12

Decreases down a group because atoms have less proton charge to pull in electrons