alleryStart learning →The calcium ion Ca2+ is isoelectronic with which noble gas?
ANeon gas
BKrypton gas
CHelium gas
DArgon gas
Answer & Solution
Correct answer: D. Argon gas
1. Isoelectronic means having the same number of electrons as another species.
2. Calcium has 20 electrons, and losing two leaves 18.
3. The calcium ion is therefore isoelectronic with the noble gas argon.
4. Neon has 10 electrons and krypton has 36, so neither matches.
5. Reaching a noble gas configuration is exactly why calcium forms a 2 plus ion.
_Source: OpenStax Chemistry 2e (CC BY 4.0), Ch 7 'Chemical Bonding and Molecular Geometry', sections 7.1-7.6_
Keep practising Chemical Bonding and Molecular Geometry
Browse all Chemical Bonding and Molecular Geometry questions for AP Chemistry, or explore more Chemistry topics.
Related questions
Complete the ionisation ruleMatch each term to its meaningWork the bonding numbersTrue or false: bondingIonic or covalent?An ionic formula such as Al2O3 does not tell you:For p-block elements forming cations, electrons are removed from which orbitals first?In a chlorine molecule, each chlorine atom ends up surrounded by how many electrons in tot