: If you mean table salt i.e. sodium chloride. It is held together by ionic bonds between sodium (Na+) and chloride (Cl-) ions. The sodium ions have a positive charge and the chlorine ions have a negative charge. Since opposite charges attract, they form ionic bonds. Ionic bonds are nothing more than the attraction between positive and negative ions.
A carbon iota can bond with four other iotas and is just like the four-hole wheel, whereas an oxygen iota, which can bond only to two, is just like the two-hole wheel.
A cold front is the leading edge of a cooler mass of air, replacing at ground level a warmer mass of air, which lies within a fairly sharp surface trough of low pressure.
