Question

When two atoms of chlorine combine to form one molecule of chlorine gas, the energy of the molecule:
(A) Greater than that of separate atoms
(B) Equal to that of separate atoms
(C) Lower than that of separate atoms
(D) None of the above

Answer 1

Hint: In chemistry, elements are not always stable in every state that it exists. The elements combine in various fashions that are optimal for them to become stable. The elements that bond do so, to increase their existence in the environment. The elements release or gain some of the electrons for achieving stability.

Complete step by step answer:
The atoms in the atmosphere exist in various forms be it in various forms. These forms include alloys, ions, or inert metals.
The reactivity of the element depends on the electronic structure of the element that means the ways the electrons are arranged in the outermost orbital of the element.
The element generally falls in one of the categories, is that is either inert and doesn’t react to other elements, release electrons to gain a stable electronic configuration to gain stability, or lose an electron to gain stability.
The electrons that are the inert elements usually have a favorable structure in their orbital and all the other elements tend to lose or gain an electron to achieve this state. So, the inert elements act as a role model for other elements.
Chlorine atoms exist in the state of chlorine ions which is negatively charged or the chlorine molecule. The chlorine atom is less stable and has high energy and thus forms a bond with another chlorine atom to gain stability.
The atoms combine to form a molecule that has energy lower than the actual chlorine atom. This decreases the net energy of the molecule and thus has higher stability.
Due to this lowering of energy the molecule is more stable.

So, the correct answer is Option C .

Note: The energy released in the reactions is usually in the form of heat. The reactions that are exothermic release energy and thus the final product of the reaction is of net lower energy. The reactions that are endothermic need heat for the reaction to carry out so the reaction tends to take that energy from the environment lowering the temperature.