Select isoelectronic species among the following Na+, Cl–, F–, Li+

Isoelectronic species are atoms, ions or molecules that have the same number of electrons.

Step 1: Determine the number of electrons in each species.

• Na+ (Sodium ion): Sodium (Na) normally has 11 electrons, but it has lost one electron to become Na+, so it has 10 electrons.
• Cl– (Chloride ion): Chlorine (Cl) normally has 17 electrons, but it has gained one electron to become Cl–, so it has 18 electrons.
• F– (Fluoride ion): Fluorine (F) normally has 9 electrons, but it has gained one electron to become F–, so it has 10 electrons.
• Li+ (Lithium ion): Lithium (Li) normally has 3 electrons, but it has lost one electron to become Li+, so it has 2 electrons.

Step 2: Compare the number of electrons in each species.

From the above, we can see that Na+ and F– both have 10 electrons.

Therefore, Na+ and F– are isoelectronic species among the given options.