Answer: Phosphorus has a half-filled 3p subshell (extra stability).
- A Phosphorus has a half-filled 3p subshell (extra stability)
- B Sulfur simply has more total electrons than phosphorus
- C Phosphorus has a lower nuclear charge than sulfur
- D Sulfur has a noticeably larger atomic radius than phosphorus
Correct answer: A. Phosphorus has a half-filled 3p subshell (extra stability)
Explanation: Phosphorus has a half-filled 3p<sup>3</sup> configuration, which is extra stable; pairing in S's 3p<sup>4</sup> makes one electron easier to remove.
The complete modern periodic table (118 elements). Image: Cepheus et al., Public Domain, via Wikimedia Commons.
Concept context
The periodic table organises all 118 elements by atomic number and similar properties. Study periodic trends like atomic radius, ionization energy, and electronegativity, and learn how an element's position predicts its behaviour.
Read the full Classification of Elements and Periodicity in Properties notes →