Ion Cr^2-

Symbol	Cr2-
Number	24
Atomic weight	51.9961000
Latin name	Chromium
English name	Chrome

How to build an electronic configuration by yourself? See link

Electronic configuration of of Chrome

Cr: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵ → Cr^2-:1s²2s²2p⁶3s²3p⁶4s¹3d⁷

The same amount of electrons as an ion of Chrome -2 have: Mn^-1, Fe, Co⁺¹, Ni⁺²

The order of filling the shells with electrons of Chrome (Cr^2-): 1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p → 5s → 4d → 5p → 6s → 4f → 5d → 6p → 7s → 5f → 6d → 7p.

On the sub level ‘s’ there might be 2 electrons at most, on ‘p’ - up to 6, on ‘d’ - up to 10 and up to 14 on ‘f’

Chrome has 24 electrons, let's fill electronic layers in described order:

2 electrons on 1s-sub level

2 electrons on 2s-sub level

6 electrons on 2p-sub level

2 electrons on 3s-sub level

6 electrons on 3p-sub level

1 electron on 4s-sub level

7 electrons on 3d-sub level

Oxidation state of Chrome

Atoms of Chrome in compounds have an oxidation state of 6, 5, 4, 3, 2, 1, 0, -1, -2, -3, -4.

The oxidation state is the conditional charge of an atom in a compound: the bond in a molecule between atoms is based on the sharing of electrons, thus, if the atom’s charge virtually increases, then the oxidation state is negative (electrons carry a negative charge), if the charge decreases, then the oxidation state is positive.

Oxidation state of an ion Cr^2- = -2

Ions of Chrome

Valence of Cr^2-

Atoms of Chrome in compounds have valence VI, V, IV, III, II, I.

Valence of Chrome is an ability of an atom Cr to build chemical bounds. The valence is based on electronic configuration of atom: electrons participated in chemical bounds are known as valence electrons. In general the valence is:

The number of possible chemical bounds with other atoms

The valence has no sign.

Quantum numbers Cr ^2-

Quantum numbers are defined by the last electron in configuration, for an ion Cr these numbers are N = 3, L = 2, M_l = -1, M_s = -½

Filling an electronic configuration (gif):



Result: