Write the formulas for the analogous species of the elements of period 3; would you expect them to have the same hybridization at the central atom?

Explanation:

The elements belonging to third period which corresponds to B,C and N are Al, Si and P. All these elements in the third period tries to combine with four of hydrogen atoms and form an analogous species.

The formulae of these species are given as

All these species have a central atom which has four electron domain and the geometry of the electron domain is tetrahedral. The hybridization which corresponds to the geometry of tetrahedral electron domain is .

So have the same hybridization at the central atom such as .

n+h→nh3

we must remember that nitrogen and hydrogen are both diatomic molecules in their standard gas form. this adjusts the equation to

n2+h2→nh3

now we need to adjust coefficients in order to balance the atoms on each side of the equation. currently we have 2 atoms of nitrogen and 2 atoms of hydrogen on the reactant side and 1 atom of nitrogen and 3 atoms of hydrogen on the product side.

we can balance the hydrogens by placing a coefficient of 2 in front of ammonia and a coefficient of 3 in front of the hydrogen.

n2+3h2→2nh3

this gives us 6 hydrogen on each side and coincidentally the nitrogens now equal 2 on each side.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.