Effective Nuclear Charge, Shielding effect, & Periodic Trends

What are the two primary forces within an atom that contribute to its chemical behavior?

• Attraction between protons and neutrons, and repulsion between electrons.

• Attraction between electrons and protons, and repulsion between electrons.

• Attraction between protons and protons, and repulsion between electrons.

• Attraction between electrons and neutrons, and repulsion between protons.

In an atom, what is the term for the outer electrons that are primarily involved in chemical reactions?

• Core electrons

• Inner electrons

• Valence electrons

• Nuclear electrons

What is the effect of inner (core) electrons on outer (valence) electrons in an atom?

• Core electrons attract valence electrons, increasing their attraction to the nucleus.

• Core electrons repel valence electrons, decreasing their attraction to the nucleus.

• Core electrons have no effect on valence electrons.

• Core electrons share their charge with valence electrons, neutralizing them.

Which equation correctly represents the effective nuclear charge (Zeff) experienced by a valence electron?

• Zeff = # protons (Z) + S

• Zeff = # protons (Z) * S

• Zeff = # protons (Z) - S

• Zeff = S - # protons (Z)

What is the effective nuclear charge (Zeff) for Lithium (Li)?

• 0

• 1

• 2

• 3

Why do atoms generally get smaller when moving from left to right across a period in the periodic table?

• The number of core electrons increases, leading to greater repulsion.

• The number of protons increases, pulling valence electrons closer to the nucleus.

• New energy shells are added, increasing the overall size.

• The valence electrons are removed, reducing the atomic radius.

When moving from Neon (Ne) to Sodium (Na) in the periodic table, what happens to the number of shielding electrons and the effective nuclear charge (Zeff)?

• Shielding electrons decrease, Zeff increases.

• Shielding electrons increase, Zeff decreases.

• Both shielding electrons and Zeff increase.

• Both shielding electrons and Zeff decrease.

What is the primary reason for the increase in atomic size when moving down a group in the periodic table?

• A decrease in the effective nuclear charge (Zeff).

• An increase in the number of protons in the nucleus.

• The addition of new principal energy shells for valence electrons.

• A decrease in electron-electron repulsion.

What is the primary reason for the increase in atomic size when moving down a group in the periodic table?

• The effective nuclear charge (Zeff) significantly increases.

• Electrons are added to new, higher energy shells, placing them farther from the nucleus.

• The number of core electrons decreases, reducing repulsion.

• The number of protons decreases, weakening the nuclear attraction.

Why does ionization energy generally increase when moving from left to right across a period in the periodic table?

• The valence electrons are added to new, higher energy shells.

• The effective nuclear charge (Zeff) decreases, making electrons easier to remove.

• The valence shell gets closer to the nucleus, and Zeff increases, leading to a stronger hold on valence electrons.

• Increased shielding from core electrons makes it easier to remove valence electrons.