Bottle of solution of sodium dodecyl sulfate for use in the laboratory. The critical micelle concentration (CMC) in pure water at 25 Â°C is 8.2 mM, and the aggregation number at this concentration is usually considered to be about 62. The micelle ionization fraction (Î±) is around 0.3 (or 30%).
Definition: A pure substance is a sample of matter with both definite and constant composition with distinct chemical properties.
An element is a substance made up of atoms with the same number of protons. Elements are the simplest substances known. They can be metals (e.g. iron, copper, sodium magnesium) or non-metals (e.g. carbon, hydrogen, oxygen, nitrogen). There are just over 100 of them.