Module 3: Trends

Question 1

Things to explore

Answer 1

Atomic radius
Ionic radius
Ionization(Electronegativity- later)

Question 2

Shielding

Answer 2

e- exist around nucleus in orbitals

• They have different energies
• They exist in different subshells(s

Question 3

Effective nuclear charge

Answer 3

Zeff = atomic#(=#p+)
Z*=Z-S
Z = atomic number
S = core e-
Relies on electron configuration
Zeff is a measure of how strong the "pull" from the nucleus is on outer e-

Question 4

examples of Zeff

Answer 4

Na[Ne]3s1 Z* = 11-10 = +1

Mg[Ne]3s^2 Z* = 12-10 = +2

Question 5

Atomic radius

Answer 5

Distance between r=distance between nuclei *0.5
As you proceed down the table, atomic radius increases due extra shell. However, as you move to the right, the atomic radius decreases due to nucleus having one more proton than the last as well as moving through shell.

Question 6

Ionic gas

Answer 6

Measure from distance between particles in ion =in gymnessing
From period 7 to 1 size decreases

Question 7

Which one has a larger radius Na or Mg

Answer 7

Mg is smaller due

Question 8

Why do cations get smaller and anions get larger?

Answer 8

Na[Ne]3s1 –> Na+ [HE]2s32p^6 Z* = 11-2 = 9
Z* = 1
The much larger Zeff causes cations to contract as the greater effective nuclear charge pulls on the “new” outer e-
Anions:
Cl [Ne]3s2 3p5 Z* = 17-10 = 7
Cl- [Ne]3s2 3p6 Z* = 17-10 = 7
For the same Z* the extra electron in an anion causes more e-/e- repulsion and anions expand.`

Question 9

Ionization energy

Answer 9

E –> E+ + e- process of losing electron
IE is promotion of an e- to n = inf. Usually the e- in the highest energy orbital is removed first as it requires the least amount of Energy.
IE increases by going up and to the right

Question 10

General trend for IE

Answer 10

Increase across the PT
increases going up the PT
IE reflects atomic size trends
Size decreases, IE increases

Question 11

Ionic radius

Answer 11

Adding an electron makes IR bigger

Removing an electron makes IR smaller

Question 12

Account for some discrepancy sees in IE trend

Answer 12

Orbital symmetry means more energy is required to pull electron away from atom.

Question 13

Account for some discrepancy sees in IE trend

Answer 13

Orbital symmetry means more energy is required to pull electron away from atom.