ENC and Shielding Effect

Question 1

Effective Nuclear Charge (ENC)

Answer 1

• Force experienced by an electron form the nucleus
• Protons cause charge to nucleus
• Every atom will have diff effect on nuclear charge (diff nucleus)

Question 2

Shielding Electrons

Answer 2

• Electrons below the valence shell/ between the nucleus and valence electrons
• Shield the valence electrons form force of nucleus

Question 3

Trend of Period in Shielding Electrons

Answer 3

• No change in the # of shielding electrons across period
• Stays the same

Question 4

Trend of Group in Shielding Electrons

Answer 4

• Going down a group causes increases in energy levels
• This causes increases in protons in nucleus, creating increase in shielding electrons

Question 5

Effective Nuclear Charge (Z^eff)

Answer 5

• The charge felt by electrons after taking into account of shielding electrons
• ENC= nuclear charge - # of shielding electrons

Question 6

ENC Trend Left-to-right in a period

Answer 6

of protons increase but shielding electrons stays the same
This causes the ENC to increase (more charge felt by valence electrons)

Question 7

ENC Trend Top-to-bottom in a group

Answer 7

Shielding electrons and protons both increase
Cancels out and causes ENC to stay the same