Which of the following non-metals reacts most readily with metals?

Analyze the question: We need the non-metal that is most reactive toward metals. Non-metals react with metals by gaining electrons, so the one with the strongest tendency to gain electrons (highest electronegativity and electron affinity) reacts most readily.

Explain the concept: Metals lose electrons to form positive ions. Non-metals gain electrons to form negative ions. The more easily a non-metal gains electrons, the more readily it reacts with metals. Reactivity of non-metals increases across a period (left to right) and decreases down a group. The halogens (Group 17) are the most reactive non-metals.

Solution:

| Non-metal | Group | Electrons needed to complete the octet | Electronegativity (approx.) | |---|---|---|---| | Carbon | 14 | 4 (usually shares) | 2.5 | | Nitrogen | 15 | 3 (very stable N≡N bond, so unreactive) | 3.0 | | Phosphorus | 15 | 3 | 2.1 | | Sulphur | 16 | 2 | 2.5 | | Chlorine | 17 | 1 | 3.0 |

• Chlorine needs only one electron to complete its octet, so it gains an electron very easily.
• It has a high electronegativity and high electron affinity.
• It reacts directly with most metals, for example: • 2Na + Cl₂ → 2NaCl (vigorous) • 2Fe + 3Cl₂ → 2FeCl₃
• Nitrogen is very unreactive because of its strong triple bond. Carbon is also relatively inert at normal temperatures. Sulphur and phosphorus react with metals only on heating, and less vigorously.

Answer: Chlorine, which is option B.

Tip: For "most reactive non-metal" questions, look for the halogen, or the element closest to fluorine in the periodic table. For "most reactive metal," look toward the bottom left (Group 1, such as K or Na).