Answer:
The smallest ion is : Mg 2+
Increasing Order of size :
Mg2+ < Na+ < F- < O2-
Explanation:
Isoelectronic Species : Species having same number of electrons .
= Effective attraction of the nucleus felt by the outer shell electrons.
<u>The size of the atom is decided by </u>:
- Its atomic number (number of proton)
- the effective nuclear charge.
As the <u>positive charge increases</u> the<u> size</u> of the <u>ion decreases.</u>
As the<u> negative charge increases </u>the<u> size </u>of ion also<u> increases.</u>
<u>Negative charged ions</u> : F- , O2-
Negative charge are formed when electrons are added to the atoms.
<u>When Negative ion is formed</u> :
- Number of proton remain same
- Number of electron get increased
Hence it becomes difficult for the proton in the nucleus to attract the electrons.
Electron - electron Repulsion increases
= decreases
<u>Size increase</u>
<u>Positive charged ions</u> : Na+ , Mg2+
Positive charge are formed when electrons are removed from the atoms.
<u>When Positive ion is formed</u> :
- Number of proton remain same
- Number of electron get reduced
Hence more attraction of the nucleus is felt by the outer electron.
Electron - electron Repulsion Decreased
= increases
<u>Size decreases</u>
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