which of the folllowing species is not isoelctric with any of the others?
a)V3+
b)Ca2+
c)Ar
d)CL-
e)S2-
This is much easier to answer if you look at a Periodic Table, say
http://en.wikipedia.org/wiki/Periodic_table
In order the elements are
Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V
adding an electron will make the element isoelectronic with the element to the right, removing an electron will make it isoelectronic with the element to the left. So
Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V
_________________________V3+
______________Ca2+
______________Cl-
______________S2-
Oh dear the formatting didn't work. I'll try again
Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V
___________________V3+
_________Ca2+
_________Cl-
_________S2-
So four are isoelectronic.
To determine which of the following species is not isoelectric with any of the others, we need to understand the concept of isoelectricity.
Isoelectronic species are atoms or ions that have the same number of electrons. In other words, they have the same electron configuration. To find the isoelectronic species, we need to examine the electronic configuration of each option:
a) V3+:
The atomic number of vanadium (V) is 23. When it loses three electrons to form the +3 cation, its electronic configuration becomes 1s2 2s2 2p6 3s2 3p6 3d2. Therefore, V3+ has the electronic configuration 1s2 2s2 2p6 3s2 3p6.
b) Ca2+:
The atomic number of calcium (Ca) is 20. When it loses two electrons to form the +2 cation, its electronic configuration becomes 1s2 2s2 2p6 3s2 3p6. Therefore, Ca2+ has the electronic configuration 1s2 2s2 2p6.
c) Ar:
Argon (Ar) is a noble gas with the atomic number 18. It has a filled electron shell, so its electronic configuration is 1s2 2s2 2p6 3s2 3p6.
d) Cl-:
Chlorine (Cl) has the atomic number 17. When it accepts one electron to form the -1 anion, its electronic configuration becomes 1s2 2s2 2p6 3s2 3p6. Therefore, Cl- has the electronic configuration 1s2 2s2 2p6 3s2 3p6.
e) S2-:
Sulfur (S) has the atomic number 16. When it gains two electrons to form the -2 anion, its electronic configuration becomes 1s2 2s2 2p6 3s2 3p6. Therefore, S2- has the electronic configuration 1s2 2s2 2p6 3s2 3p6.
To determine which species is not isoelectric with any of the others, we need to compare their electronic configurations. From the above analysis, it is clear that option c) Ar has a different electronic configuration (1s2 2s2 2p6 3s2 3p6) compared to the other options (1s2 2s2 2p6 3s2 3p6). Therefore, the species Ar is not isoelectric with the others.
So, the answer is c) Ar.