Calcium has an atomic number of 20 and 2 valence electrons. Oxygen has an atomic number of 8 and 6 valence electrons. Neon has an atomic number of 10 and 8 valence electrons. Explain how the placement of these three elements on the periodic table compares and why they are placed where they are relative to each other.

Calcium is in group 2 period 4 of periodic table

Oxygen is in group 16 and period 2

neon is in period 2 and group 16.

Explanation:

Valence electron in calcium =2

valence electron in oxygen= 6

valence electron in neon= 8 valence electron.

 Calcium is placed in s block group 2 of period 4.

oxygen is placed in period 2 and group 16

Neon is a p block element, placed in period 2 and group 16.

Calcium is a elecropositive element which can share or donates its electrons to for compound, it has oxidation state of +2 and hence placed in group 2

Oxygen is electronegative as it can accept or share 2 electrons to form a bond. It has oxidation of -2.

Example is CaO.

Neon has its outer shell complete it is an inert element which will not share or donate electrons. it has oxidation state of 0

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