Why is energy required to break a covalent bond

Energy is required to break a covalent bond as a result of its necessity in the

formation of products.

Atoms in a covalent bond are usually much stable as a result of them

achieving the octet configuration. Energy is thereby required to break the

bonds in order to permit the interaction of the electrons of the substances

involved.

The interaction of the electrons is what acts as a precursor in the formation

of new products.

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the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.