Question

1. the ionization energies for an element from period 3 are listed below. based on the data, the element is most likely:

1st 2nd 3rd 4th 5th
8 ev 15 ev 80 ev 109 ev 141 ev

Explanation:

Step1: Recall ionization energy trends

Ionization energy (IE) is the energy required to remove an electron from an atom. A large jump in IE indicates a change in electron shell (removing an electron from a more stable, inner shell). For period 3 elements, valence electrons are in the 3rd shell. After removing valence electrons, IE jumps when removing from the 2nd shell (core electrons).

Step2: Analyze the IE data

• 1st IE: 8 eV, 2nd IE: 15 eV (both relatively low, removing valence electrons).
• 3rd IE: 80 eV (large jump, now removing from a core shell, meaning the first two electrons were valence, and the 3rd is a core electron).

Step3: Determine valence electrons

Elements in period 3: Na (1 valence e⁻), Mg (2 valence e⁻), Al (3), Si (4), P (5), S (6), Cl (7), Ar (8). A large jump between 2nd and 3rd IE means the element has 2 valence electrons (since after removing 2, the next is a core electron). Mg has 2 valence electrons (electron configuration: \(1s^2 2s^2 2p^6 3s^2\)). Removing the two 3s electrons (1st and 2nd IE) is easy, then removing from 2p⁶ (core) requires much more energy (3rd IE jump).

Answer:

Magnesium (Mg)