5. Electrons and shielding

Question 1

What is the limitation of the Schrodinger equation in relation to electrons?

Answer 1

I can’t be solved exactly for an atom with many electrons

The solution for H atom can be used for other atoms

Question 2

On what does the E of e depend for H and other atoms

Answer 2

For H depends only on the quantum number n

For all other atoms depends on quantum number n and l

Question 3

Explain the fourth quantum number

Answer 3

Question 4

Explain Pauli exclusion principle

Answer 4

Question 5

Explain the Aufbau principle and Hund’s rule

Answer 5

Degenerate orbitals - orbitals of the same energy

Question 6

What is the case when the Aufbau principle doesn’t work?

Answer 6

Less E configuration achieved

Question 7

Explain the concept of shielding

Answer 7

Outer electrons are partially shielded from the attractive force of the protons in the nucleus by inner electrons.

Question 8

Explain effective nuclear charge

Answer 8

Effective nuclear charge - net positive charge experienced by an electron in a polyelectronic atom

Shielding effect of negatively charged e prevent higher orbital e from experiencing the full nuclear charge of the nucleus due to the repelling effect of inner-layer e

Question 9

Do 1s e feel the full nuclear charge?

Answer 9

Question 10

Explain penetration in orbials

Answer 10

s orbitals tend to penetrate close to the nucleus

The closer the orbital to nucleus (the lower n quantum #) → the larger penetration → the better shielding

s>p>d>f

Question 11

Which properties are affected by shielding?

Answer 11

• Ionisation E
• atomic size