Electrons in an atom can be classified as core electrons and valence electrons. Valence electrons are those electrons which are present in valence shell and participates in bond formation. While, Core electrons are all remaining electrons which are not present in valence shell, hence not take part in bonding.
Atomic number of Selenium (Se) is 34 hence it has 34 electrons with following electronic configuration;
1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁴
From electronic configuration it is found that the valence shell is 4, and the number of electrons present in valence shell are 6. So,
Core Electrons = Total Electrons - Valence Electrons
Core Electrons = 34 - 6
Core Electrons = 28
Result:
There are 28 core electrons in Selenium.
There are 1000 meters in 1 Kilometer.
Hope this helps you. :)
Answer:
MgBr2
Explanation:
On the periodic table, Magnesium has 2+ charge and Bromine has -1 charge.
You cross charges and get MgBr2
<u>Answer:</u>
<u>When an alkyl benzene is heated with strong oxidizing asgents like acidic or alkline KMnO4</u>
<u> or acidified K2Cr2O7</u>
<u>, etc. gives aromatic carboxyllic acid. The alkyl side chain gets oxidised to −COOH</u>
<u> group irrespective of the size of the chain.</u>
Explanation:
