Question

What element forms an ion with an electronic configuration of 1s22s22p63s23p63d104s24p6 (or [kr]) and a −2 charge? Give the symbol for the element?

Answer 1

Answer :  The symbol of the element is Selenium (Se).

Explanation :  

Electronic configuration is distribution of electrons in an atom in                    atomic orbitals.

The electronic configuration of [Kr] =  $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{6}$

Total number of electrons in [Kr] = 36

Due to -2 charge, 2 electrons are withdrawn from the electronic configuration of [Kr].

Now the total number of electrons left = 36 - 2 = 34

And the Selenium[Se] is the element which has 34 number of electrons.

Electronic configuration of [Se] = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{10}4s^{2}4p^{4}$

Answer 2

Electronic configuration is the systematic representation of the electrons filled in the orbitals of an element or atom. The electronic configuration of $\text{1s}^2\;\text{2s}^2\;\text{2p}^{6}\;\text{3s}^{2}\;\text{3p}^6\;\text{3d}^{10}\;\text{4s}^2\;\text{4p}^6 \text{(or [kr])}$ can be represented by the element Selenium or Se.

Electronic Configuration is the distribution of electrons in the orbitals or shells of the elements. The electronic configuration for Krypton or Kr is:

• $\text{[Kr]}&=\text{1s}^2\;\text{2s}^2\;\text{2p}^{6}\;\text{3s}^{2}\;\text{3p}^6\;\text{3d}^{10}\;\text{4s}^2\;\text{4p}^6$

Total number of electrons in Kr is  = 36

Given that,

The negative charge of 2 will result in the total number of electrons to be:

No. of electrons = 36 - 2 = 34

The 34 is the atomic number of selenium or Se, such that the electronic configuration of Selenium is:

• $\text{[Se]}&=\text{1s}^2\;\text{2s}^2\;\text{2p}^{6}\;\text{3s}^{2}\;\text{3p}^6\;\text{3d}^{10}\;\text{4s}^2\;\text{4p}^4$

Therefore, the number of electrons in the Selenium and Krypton ion is same, which is 34.

To know more about electronic configuration, refer to the following link:

https://brainly.com/question/3609895?referrer=searchResults