Question

use the periodic table to answer the following questions.
what is the predicted order of first ionization energies from highest to lowest for beryllium, calcium, magnesium, and strontium?
$\boldsymbol{circ}$ be > ca > mg > sr
$\boldsymbol{checkmark}$ be > mg > ca > sr
$\boldsymbol{circ}$ ca > sr > be > mg
$\boldsymbol{circ}$ sr > ca > mg > be
complete
what is the predicted order of first ionization energies from highest to lowest for aluminum, phosphorus, silicon, and sulfur?
$\boldsymbol{circ}$ al > p > si > s
$\boldsymbol{circ}$ al > si > p > s
$\boldsymbol{circ}$ s > p > si > al
$\boldsymbol{circ}$ p > s > si > al
done

Explanation:

1. For beryllium (Be), calcium (Ca), magnesium (Mg), strontium (Sr): These are Group 2 elements. First ionization energy decreases down a group as atomic radius increases, so the order from highest to lowest is Be > Mg > Ca > Sr.
2. For aluminum (Al), phosphorus (P), silicon (Si), sulfur (S): These are Period 3 elements. Ionization energy generally increases across a period, but P has a higher ionization energy than S because P has a half-filled stable 3p subshell. So the order from highest to lowest is P > S > Si > Al.

Answer:

1. Be > Mg > Ca > Sr
2. P > S > Si > Al