Practice: What is the identity of an element when the effective nuclear charge of its valence electrons is 18 while its shielding constant is 5?
Effective Nuclear Charge (Zeff) measures the force exerted onto an electron by the nucleus.
Effective Nuclear Charge
Concept #1: Periodic Trend: Effective Nuclear Charge
Higher the Effective Nuclear Charge (ZEff), greater the attractive force, which results in electrons being pulled closer to the nucleus.
Higher the Shielding Constant (S), greater the repulsive force between valence and inner core electrons, which results in valence electrons pushed away from the nucleus.
Concept #2: Periodic Trends
Moving towards the top right corner of the Periodic Table causes effective nuclear charge to increase.
Example #1: Which of the following represents a chalcogen with the greatest effective nuclear charge?
Concept #3: Calculate without Slater’s Rules
Example #2: What is the effective nuclear charge felt by an electron in the third shell of an aluminum atom?
Example #3: Using Slater’s Rules, calculate the effective nuclear charge of a 3p orbital electron in calcium.
Practice: In which orbital does an electron in a sulfur atom experience the greatest shielding?
Practice: Rank the following elements by effective nuclear charge, ZEff, for a valence electron: Kr, Se, Ca, K, Ge
Practice: Using Slater’s Rules calculate the effective nuclear charge of the 4d orbital electron in iodine.