Question

True or False: Atoms with the greatest electronegativities are those that have the greater nuclear charge, but only when the number of shells is the same. Explain.

Short answer

True, under identical shell conditions, a greater nuclear charge leads to higher electronegativity.

Step-by-step solution

Understanding Electronegativity

Electronegativity refers to an atom's ability to attract and hold onto electrons during bonding. Generally, the greater the electronegativity, the more strongly an atom will attract electrons.

Analyzing Nuclear Charge

The nuclear charge of an atom is determined by the number of protons in its nucleus. A greater nuclear charge increases the atom's ability to attract electrons due to the stronger positive force exerted by the nucleus.

Considering the Number of Electron Shells

When the number of electron shells (or energy levels) is the same across different atoms, the shielding effect (reduction in effective nuclear charge due to electron-electron repulsion in outer shells) is minimized. This allows the nuclear charge to affect electron attraction more directly.

Evaluating the Proposition

Atoms with the greatest electronegativities do indeed possess a greater nuclear charge when the number of shells is the same. The minimal shielding effect allows the nuclear charge to play a significant role in electron attraction, leading to high electronegativity.

Final Determination

Given the conditions specified (greater nuclear charge and equal shell number), the statement is true. Atoms with higher nuclear charges under the same shell conditions typically have higher electronegativities.

Key concepts

Nuclear Charge

Nuclear charge is an important concept in understanding how atoms interact with electrons. It refers to the total charge of an atom's nucleus, which is determined by the number of protons contained within it. Protons have a positive charge, and the more protons present, the greater the nuclear charge.
This charge creates an attractive force on electrons, pulling them toward the nucleus.
Nuclear charge plays a crucial role in determining an atom's electronegativity, which is the tendency of an atom to attract additional electrons when forming chemical bonds.

• The greater the nuclear charge, the stronger the attraction for electrons.
• As nuclear charge increases, electronegativity tends to increase as well.

In molecules, nuclear charge can significantly influence which atoms attract electrons more effectively, thus impacting molecular shape and reactivity.

Electron Shells

Electron shells, also known as energy levels, are layers surrounding the nucleus where electrons reside. These shells are critical in determining an atom's chemical properties, including electronegativity.
The arrangement of electrons in shells helps manage how tightly an atom can hold onto its electrons and influences its ability to attract new ones.

• Electrons closer to the nucleus in lower energy shells experience a stronger attraction due to less shielding effect.
• Electrons in higher energy shells are further out and experience a weaker attraction to the nucleus.

When comparing atoms with the same number of electron shells, the influence of nuclear charge is more direct, as there are no additional layers to weaken the pull of the nucleus.
This allows for more straightforward comparisons of electronegativity between atoms, based largely on their nuclear charge.

Shielding Effect

The shielding effect occurs when inner electron shells reduce the effective nuclear charge felt by outer electrons.
This happens because inner electrons repel the outer ones, diminishing the attractive pull from the nucleus.
The more electron shells an atom has, the greater the shielding effect can become, impacting electronegativity in the following ways:

• The shielding effect reduces the effective nuclear charge, decreasing electronegativity.
• Greater shielding leads to less attraction of additional electrons.

When the number of electron shells in atoms is the same, the shielding effect is minimized, allowing the nuclear charge to be the main factor affecting electronegativity.
This explains why, with the same shell number, atoms having a greater nuclear charge also have higher electronegativities.