6atoms of element a combine with 8 atoms of element b to produce 6 compound particles. how many atoms of elemnt a and element b does each particle contain? are all atoms used to form compounds?

Each molecule contains one atom of A and one atom of B. The reaction does not use all of the atoms to form compounds.

                  A + B ⟶ Product

Particles: 6      8              6

If six A atoms form six product molecules, each molecule can contain only one A atom.

The formula of the product is ABₙ.

If n = 1, we need six atoms of B.

If n = 2, we need 12 atoms of B. However, we have only eight atoms of B, so the formula of the product must be AB.

Thus, 6A + 6B ⟶ 6AB, with two B atoms left over.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.