Which statement about isoelectronic species is true?

Which statement about isoelectronic species is true?

• A. True
• B. False
• C. Only occurs for noble gases
• D. It requires identical numbers of protons

Answer: (A)

Isoelectronic species are defined by having the same number of electrons, which gives them the same electron configuration as a noble gas with that electron count. For example, Ne, Na+, and F− all have 10 electrons and share the same 1s2 2s2 2p6 configuration. The key idea is that electron count, not the number of protons, determines isoelectronic relationships. Different nuclei can have different charges, so the atoms or ions can have different sizes or nuclear attractions even when their electron counts match. That’s why isoelectronic species aren’t limited to noble gases and don’t require identical proton numbers.

Isoelectronic species are defined by having the same number of electrons, which gives them the same electron configuration as a noble gas with that electron count. For example, Ne, Na+, and F− all have 10 electrons and share the same 1s2 2s2 2p6 configuration. The key idea is that electron count, not the number of protons, determines isoelectronic relationships. Different nuclei can have different charges, so the atoms or ions can have different sizes or nuclear attractions even when their electron counts match. That’s why isoelectronic species aren’t limited to noble gases and don’t require identical proton numbers.