Effective Nuclear Charge Flashcards
(9 cards)
What is effective nuclear charge?
A measure of the attractive force felt by the valence shell towards the nucleus.
Effective nuclear charge helps predict properties of elements and explains trends in the periodic table.
How does effective nuclear charge relate to lithium?
Lithium has an effective nuclear charge of +1 due to 3 protons and 2 inner shell electrons shielding the valence electron.
Lithium’s atomic number is 3, with 2 electrons in the first shell and 1 in the second.
What is the formula for calculating effective nuclear charge?
Effective nuclear charge = number of protons – number of electrons in the inner shells.
This formula accounts for the shielding effect of inner shell electrons.
What is the effective nuclear charge of chlorine?
+7, calculated from 17 protons and 10 inner shell electrons.
Chlorine has 7 valence electrons.
Determine the effective nuclear charge of an atom of helium.
Helium has an effective nuclear charge of +2.
Helium has 2 protons and no inner shell electrons.
What is the trend in effective nuclear charge down a group?
Remains constant.
Valence electrons are held less strongly due to increased distance from the nucleus and more inner shells.
What happens to the effective nuclear charge left to right across a period?
Increases.
Valence electrons are more attracted to the nucleus as effective nuclear charge increases.
True or False: The effective nuclear charge of a main group element is equal to the number of valence electrons.
True.
This observation highlights the relationship between effective nuclear charge and valence electrons.
What is the shielding effect?
The reduction in attraction between the nucleus and valence shell electrons due to inner shell electron repulsion.
This effect is significant in atoms with multiple electron shells.
