Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the
Shades of cyan verdigris was the most vibrant green pigment available and was frequently used in painting. Verdigris was sometimes used to illustrate cyan colors in early color wheels. Viridian is a blue-green pigment, a hydrated chromium(III) oxide, of medium saturation and relatively dark in value. It is composed more of green than blue. Specifically, it is a dark shade of spring green, the color between green and cyan on the color wheel, or, in paint, a tertiary blue–green color. Viridian takes its name from the Latin "viridis", meaning "green". The first recorded use of "viridian" as a color name in English was