A chemical composition specifies the identity, arrangement, and ratio of the

elements Element or elements may refer to: Science * Chemical element, a pure substance of one type of atom * Heating element, a device that generates heat by electrical resistance * Orbital elements, parameters required to identify a specific orbit of ...

making up a compound. Chemical formulas can be used to describe the relative amounts of elements present in a compound. For example, the chemical formula for water is H₂O: this means that each molecule of water is constituted by 2

atom Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas ...

s of hydrogen (H) and 1 atom of oxygen (O). The chemical composition of water may be interpreted as a 2:1 ratio of hydrogen atoms to oxygen atoms. Different types of chemical formulas are used to convey composition information, such as an

empirical Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...

or molecular formula. Nomenclature can be used to express not only the elements present in a compound but their arrangement within the

molecules A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...

of the compound. In this way, compounds will have unique names which can describe their elemental composition.

Composite mixture

The chemical composition of a

mixture In chemistry, a mixture is a material made up of two or more different chemical substances which are not chemically bonded. A mixture is the physical combination of two or more substances in which the identities are retained and are mixed in the ...

can be defined as the distribution of the individual substances that constitute the mixture, called "components". In other words, it is equivalent to quantifying the concentration of each component. Because there are different ways to define the concentration of a component, there are also different ways to define the composition of a mixture. It may be expressed as molar fraction, volume fraction, mass fraction, molality, molarity or normality or

mixing ratio In chemistry and physics, the dimensionless mixing ratio is the abundance of one component of a mixture relative to that of all other components. The term can refer either to mole ratio (see concentration) or mass ratio (see stoichiometry). In at ...

. Chemical composition of a mixture can be represented graphically in plots like ternary plot and quaternary plot.

References

{{reflist Chemical properties Analytical chemistry pt:Composição química