Ion electron configuration and radius

Positively charged ions are called positive ions or cations, and negatively charged ions are called negative ions or anions
.

1.
Ionic charge

Ionic charge is the number of electrons lost or gained by atoms in the process of forming ionic compounds
.

2.
Ion electron configuration

Simple ions generally have a stable 8 electronic configuration, such as F.
^- , CI ^- , O ^{2 -} , S ^{2 -} like structure the outermost layer of a rare gas have 8 electrons
.

2 Electronic configuration: ns ² , there are 2 electrons in the outermost layer, such as Li ⁺ , Be ²⁺ and so on
.

8 electron configuration: ns ² np ⁶ , there are 8 electrons in the outermost layer, such as Na ⁺ , K ⁺ , Mg ²⁺ and so on
.

(9-17) Electronic configuration: ns ² mp ⁶ nd ^1-9 , with 9-17 electrons in the outermost layer, such as Fe ²⁺ , Mn ²⁺ , Cu ²⁺ and so on
.

18 electronic configuration: NS ² NP ^.
6 Nd ¹⁰ , outermost layer 18 electrons, such as a Cu ⁺ , of Ag ⁺ , a Zn ²⁺ , Hg ²⁺ and the like
.

(18+2) electronic configuration: (n-1)s ² (n-1)p ⁶ (n-1)d ¹⁰ ns ² , there are 18 electrons in the second outer layer and 2 electrons in the outermost layer, such as Tl ⁺ , Pb ²⁺ , Bi ³⁺ and so on
.

3.
Ionic radius

If the ions as spheres, positive and negative ions in the crystal nucleus tangential spacing d at a positive ions and negative ions radius radii r + and r- sum (FIG.
6-1), i.
e.
, = R & lt d ⁺ + R & lt ^-
.

Figure 6-1 The relationship between nuclear distance and ion radius

The nucleus distance d of the ionic crystal can be easily measured by X-ray diffraction method
.

In 1926, German VM Goldchmidt determined from optical data that the F ^- and O ^2- radii were 133pm and 132pm, respectively
.

In 1927, Pauling fully considered the effects of nuclear charge and shielding constant and calculated a set of ion radius
.

(1) Elements of the same main group with the same charge increase successively with the number of electron layers, and the ionic radius also increases successively
.

Li ⁺ <of Na ⁺ <K ⁺ <Rb ⁺ <Cs ⁺          F.
^- <CI ^- <Br ^- <the I ^-

(2) In the same periodic element, the higher the charge number of positive ions, the smaller the radius; the higher the charge number of negative ions, the larger the radius
.

Na ⁺ > of Mg ^{2 +} > of Al ³⁺               P ^3- > S ^2- > a C1 ^-

(3) For the same ion, the radius increases as the coordination number increases
.

(4) Ions of the same element and different valence states have a small radius with a higher charge
.
E.
g

Fe ^{3 +} <Fe ²⁺                       Sn ⁴⁺ <Sn ²⁺