Image from W.H. Freeman and Sinauer Associates, used by permission. Those atoms are held together usually by one of the three bonds discussed above. Molecular formulas are an expression in the simplest whole-number terms of the composition of a substance. Determination of molecular weights by addition of the weights of the atoms that make up the molecule. Image from W.H. Freeman and Sinauer Associates, used by permission.
Chemical reactions occur in nature, and some also can be performed in a laboratory setting.
Chemical Equations are linear representations of how these reactions occur. This chemical reaction takes place in a camping stove as well as in certain welding torches. Image from W.H. Freeman and Sinauer Associates, used by permission. Biological systems, while unique to each species, are based on the chemical bonding properties of carbon. All forms of matter are composed of one or more elements.