12. Atomic Structure (HL)

Question 1

Ionization energy

Answer 1

Energy required to remove one electron from each atom in one mole of gaseous atoms under standard conditions

Question 2

Unit for ionization energy

Answer 2

kJ/mol

Question 3

What is Planck’s constant?

Answer 3

6.63 x 10^-34 Js

Question 4

What is relationship between energy and frequency?

Answer 4

Energy = hv (Planck’s constant x frequency of light)

Question 5

How do you calculate speed of light?

Answer 5

c= v x lambda (frequency x wavelength)

Question 6

What can you derive from the two equations: E= hv and c= v*lambda

Answer 6

E= hc/lambda a.k.a the energy of photons

Question 7

What is first ionization energy?

Answer 7

Energy required to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions

Question 8

What is second ionization energy of magnesium?

Answer 8

Mg+ –> Mg2+ + e-

Question 9

Why are ionization energies always positive?

Answer 9

They have to be added to overcome electrostatic attraction between nucleus and valence electrons hence it is endothermic

Question 10

Why is 2nd ionization energy higher than the first?

Answer 10

As first electron is removed, effective nuclear charge increases and charge becomes positive. Increase in attraction means more energy is required to overcome

Question 11

What should you remember when calculating ionization energy?

Answer 11

You have to multiply e=hv into 6.02*10^23 as you are calculating for 1 mole (Unit becomes kJ/mol)

Question 12

What is the energy of convergence limit?

Answer 12

It is the energy absorbed from n=1 to n=infinity

Question 13

Successive ionization energies

Answer 13

Consecutive energies required when removing electrons until only nucleus remains

Question 14

What should you always refer to in an answer about ionization energies?

Answer 14

• Proton number
• Shielding effect
• No. of energy levels
• Atomic radius
• Effective nuclear charge

Question 15

What is trend of ionization energy down a group?

Answer 15

It decreases as:

• proton number increases but
• energy levels increase
• shielding effect increase so effective nuclear charge decreases

Question 16

What is trend of ionization energy across a period?

Answer 16

It generally increases as:

• proton number increases
• shielding effect remains the same so effective nuclear charge increases and is hence stronger requiring more energy

Question 17

Why are Magnesium and Aluminum exceptions to the general trend of first ionization energy?

Answer 17

Magnesium has a higher first ionization energy because it has a complete s subshell while Aluminum has one valence electron in a p subshell making it easier to remove than Magnesium

Question 18

Why are Phosphorus and Sulfur exceptions to the general trend of ionization energy?

Answer 18

Phosphorus has higher first ionization energy than sulfur because it has 3 half paired orbitals while sulfur has 1 paired orbital. It’s easier to remove a paired electron because of repulsion and so sulfur has a lower first ionization energy

Question 19

Q) X has ionization energies: 500, 1100, 3000, 3900. Which group is it in?

Answer 19

It is in Group 2 because biggest jump is between 2nd and 3rd ionization energy so it likely has 2 valence electrons as it is harder to remove an electron from a stable configuration and one that’s closer to the nucleus