Final answer:
Atoms bond to achieve stable electron configurations by filling their outermost shells, similar to noble gases. Covalent bonds involve sharing valence electrons, and vary from pure to polar covalent based on electronegativity differences.
Step-by-step explanation:
Atoms bond to achieve stability in their electron configurations.
Atoms seek to reach a state reminiscent of noble gases, which have full valence electron shells and are inherently stable. When atoms form covalent bonds, they share valence electrons to fill their outermost shells, achieving a stable electronic arrangement. An example of such bonding is seen in diamond, where carbon atoms bond covalently in a crystal lattice. Each carbon atom shares electrons with four others, forming a regular tetrahedron and completing the octet for each carbon atom, indicative of full valence shells and stability.
For instance, chlorine has seven valence electrons and by forming a Cl₂ molecule through a covalent bond, each chlorine atom can complete its valence shell. The various types of covalent bonds include pure or nonpolar covalent bonds (equally shared electrons) and polar covalent bonds (unequally shared electrons), depending on the electronegativity difference between the bonding atoms.