Molecule Chemistry

a ball-and-stick representation of caffeine molecule (c8h10n4o2).

a molecule smallest indivisible portion of pure chemical substance has unique set of chemical properties, is, potential undergo set of chemical reactions other substances. however, definition works substances composed of molecules, not true of many substances (see below). molecules typically set of atoms bound covalent bonds, such structure electrically neutral , valence electrons paired other electrons either in bonds or in lone pairs.

thus, molecules exist electrically neutral units, unlike ions. when rule broken, giving molecule charge, result named molecular ion or polyatomic ion. however, discrete , separate nature of molecular concept requires molecular ions present in well-separated form, such directed beam in vacuum in mass spectrometer. charged polyatomic collections residing in solids (for example, common sulfate or nitrate ions) not considered molecules in chemistry. molecules contain 1 or more unpaired electrons, creating radicals. radicals comparatively reactive, some, such nitric oxide (no) can stable.

a 2-d skeletal model of benzene molecule (c6h6)

the inert or noble gas elements (helium, neon, argon, krypton, xenon , radon) composed of lone atoms smallest discrete unit, other isolated chemical elements consist of either molecules or networks of atoms bonded each other in way. identifiable molecules compose familiar substances such water, air, , many organic compounds alcohol, sugar, gasoline, , various pharmaceuticals.

however, not substances or chemical compounds consist of discrete molecules, , indeed of solid substances make solid crust, mantle, , core of earth chemical compounds without molecules. these other types of substances, such ionic compounds , network solids, organized in such way lack existence of identifiable molecules per se. instead, these substances discussed in terms of formula units or unit cells smallest repeating structure within substance. examples of such substances mineral salts (such table salt), solids carbon , diamond, metals, , familiar silica , silicate minerals such quartz , granite.

one of main characteristics of molecule geometry called structure. while structure of diatomic, triatomic or tetra atomic molecules may trivial, (linear, angular pyramidal etc.) structure of polyatomic molecules, constituted of more 6 atoms (of several elements) can crucial chemical nature.