Question

Rank the elements by effective nuclear charge, eff, for a valence electron primarily based on:

a) Atomic number
b) Atomic mass
c) Electron configuration
d) Ionization energy

Answer 1

The elements can be ranked by effective nuclear charge
`(\(Z_{\text{eff}}\))`primarily based on c) Electron configuration. Therefore the correct answer is option c.

Step-by-step explanation:

Effective nuclear charge
`(\(Z_{\text{eff}}\))` is a measure of the net positive charge experienced by a valence electron in an atom, influencing its behavior in chemical reactions. The electron configuration, denoted by option c), plays a crucial role in determining
`\(Z_{\text{eff}}\). \(Z_{\text{eff}}\)` is influenced by the number of protons in the nucleus and the shielding effect caused by inner-shell electrons. The higher the effective nuclear charge, the stronger the attractive force on the valence electron.

The electron configuration dictates the arrangement of electrons in different energy levels and sublevels around the nucleus. As we move across a period in the periodic table, the atomic number increases, leading to a higher number of protons in the nucleus.

However, the shielding effect of inner electrons may not increase proportionally, resulting in a stronger
`\(Z_{\text{eff}}\)` for valence electrons. This is particularly evident in elements with half-filled or completely filled sublevels, where the added repulsion between electrons is minimized, leading to a higher
`\(Z_{\text{eff}}\)` for valence electrons.

In summary, the electron configuration is a key factor in determining the effective nuclear charge experienced by valence electrons. Understanding the arrangement of electrons within an atom provides insights into the atomic properties and behaviors of elements, crucial for predicting trends in chemical reactivity across the periodic table. Therefore the correct answer is option c.