If an element contains 8 electrons how many electrons will be placed in the 2nd valence shell?

The number of electrons that will be placed in the second valence shell is 6 electrons

From a background understanding of the arrangement of electrons around the nucleus of atom, we understood that the 1st shell will hold a maximum of 2 electrons, while other shells a maximum of 8 electrons.

Considering the question given above, we have:

Total electron = 8 electrons

Remaining electrons = 8 – 2

Since the remaining elections is not more than 8 electrons, they will be place in the 2nd shell i.e

Thus, we can conclude that the 2nd shell will have 6 electrons.

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since the atomic number is the number of protons in the nucleus, as we move to the left on the periodic table, the electrostatic pull between the nucleus and the valence electron shell decreases. as we move down a group (vertical column), the valence shell energy level gets further and further from the nucleus.

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2