Ion Se^2-

Symbol	Se2-
Number	34
Atomic weight	78.9710000
Latin name	Selenium
English name	Selenium

How to build an electronic configuration by yourself? See link

Electronic configuration of of Selenium

Se: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁴ → Se^2-:1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶

Same electronic configuration has an ion of Selenium -2 and As^-3, Br^-1, Kr, Rb⁺¹, Sr⁺², Y⁺³, Zr⁺⁴, Tc⁺⁷

The order of filling the shells with electrons of Selenium (Se^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’

Selenium has 34 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

2 electrons on 4s-sub level

10 electrons on 3d-sub level

6 electrons on 4p-sub level

Oxidation state of Selenium

Atoms of Selenium in compounds have an oxidation state of 6, 4, 2, 1, -2.

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 Se^2- = -2

Ions of Selenium

Valence of Se^2-

Atoms of Selenium in compounds have valence VI, IV, II, I.

Valence of Selenium is an ability of an atom Se 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 Se ^2-

Quantum numbers are defined by the last electron in configuration, for an ion Se these numbers are N = 4, L = 1, M_l = 1, M_s = -½

Filling an electronic configuration (gif):



Result: