Chemical Bonding, Equations, Nomenclature and Reactions

Atoms bond because having a full outer shell of electrons is more stable than having a half-empty one. Metals like sodium hold their outer electron loosely, so they give it away entirely to a nonmetal like chlorine, which wants one more electron to fill its shell. The result is an ionic bond: sodium becomes a positive ion, chlorine becomes a negative ion, and the two stick together by opposite-charge attraction. That's why sodium chloride, table salt, behaves nothing like raw sodium or raw chlorine gas. The compound has its own identity, set by the bond, not by averaging the ingredients. Covalent bonds work differently: instead of one atom giving an electron away, two atoms each contribute an electron and share the pair between them, which is how nonmetals like carbon, oxygen, and hydrogen link up in molecules such as CH4 or H2O.

A chemical equation is a bookkeeping statement: every atom present before the reaction has to still be present after, just rearranged into new molecules. Balancing means adjusting the coefficients in front of each formula until the count of each element matches on both sides of the arrow. You never change the subscripts inside a formula, since that would describe a different substance entirely; you only scale whole molecules up or down. This atom-counting rule is the same reason mass is conserved in a sealed reaction: if no atoms disappear, the total mass on the balance can't change either. Bonding explains why substances have the properties they do, and balancing equations is just tracking that bonding rearranging itself without any atom vanishing.