Skip to main content
Ch.7 - Periodic Properties of the Elements
Chapter 7, Problem 31c

Consider the isoelectronic ions F- and Na+. (c) Repeat this calculation using Slater’s rules to estimate the screening constant, S.

Verified step by step guidance
1
Understand the concept of isoelectronic ions: Isoelectronic ions have the same number of electrons. In this case, F⁻ and Na⁺ both have 10 electrons.
Slater's rules are used to estimate the effective nuclear charge (Z_eff) experienced by an electron in a multi-electron atom. The effective nuclear charge is calculated using the formula: Z_eff = Z - S, where Z is the atomic number and S is the screening constant.
To calculate the screening constant (S) using Slater's rules, first identify the electron configuration of the ions. For F⁻, the electron configuration is 1s² 2s² 2p⁶, and for Na⁺, it is also 1s² 2s² 2p⁶.
Apply Slater's rules to determine the screening constant (S) for each ion. According to Slater's rules, electrons in the same group (n) contribute 0.35 to the screening constant, while electrons in the n-1 group contribute 0.85, and electrons in the n-2 or lower groups contribute 1.00.
Calculate the screening constant (S) for both F⁻ and Na⁺ using the electron configurations and Slater's rules. Compare the values to understand how the effective nuclear charge differs between these isoelectronic ions.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
5m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Isoelectronic Species

Isoelectronic species are atoms or ions that have the same number of electrons and, therefore, the same electronic configuration. In this case, F<sup>-</sup> and Na<sup>+</sup> both have 10 electrons, making them isoelectronic. Understanding this concept is crucial for comparing their chemical properties and behaviors, as they exhibit similar electron arrangements despite differing nuclear charges.
Recommended video:
Guided course
03:03
Amphoteric Species

Slater's Rules

Slater's rules provide a systematic method for estimating the effective nuclear charge experienced by an electron in a multi-electron atom. The rules involve calculating a screening constant (S) based on the contributions of other electrons to shield the nucleus's positive charge. This concept is essential for understanding how electron-electron interactions influence atomic properties and reactivity.
Recommended video:
Guided course
06:35
Effective Nuclear Charge Calculation with Slater's Rules

Screening Constant (S)

The screening constant (S) quantifies the extent to which inner electrons shield outer electrons from the full effect of the nuclear charge. A higher S value indicates greater shielding, which affects the effective nuclear charge felt by an electron. Calculating S using Slater's rules allows for a more accurate prediction of atomic behavior, particularly in isoelectronic species where electron configurations are identical.
Recommended video:
Guided course
01:14
Equilibrium Constant K