The electrons in the atoms of two elements X and Y are distributed in three shells having 1 and 7 electrons respectively in their outermost shells.
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer
(a) Element X has 1 electron in its outermost shell → Group 1. Element Y has 7 electrons in its outermost shell → Group 17.
(b) X donates 1 electron and Y accepts 1 electron. The molecular formula is XY (e.g., NaCl type). (Formula: XY)
(c) Element X is electropositive, as it tends to lose electrons and form a positive ion.
Source: Chapter 3, Section 3.3
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Explanation
- Elements with 1 valence electron are in Group 1 (alkali metals); elements with 7 are in Group 17 (halogens).
- Since X needs to lose 1 electron and Y needs to gain 1, they combine in a 1:1 ratio → formula XY.
- Electropositive elements are those that lose electrons easily (metals/Group 1), so X is electropositive. Examiners expect you to justify briefly — "loses electrons" is the key phrase.