A chemical substance is a form of matter that has constant chemical composition and characteristic properties.
Chemical composition, also known as chemical makeup or simply, composition, is a concept in chemistry that has different, but similar, meanings if referred to a single pure substance or a mixture.
An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge.
Before the 20th century, the term matter included ordinary matter composed of atoms and excluded other energy phenomena such as light or sound.
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It cannot be separated into components by physical separation methods, i.e., without breaking chemical bonds.
In mathematics, a ratio is a relationship between two numbers indicating how many times the first number contains the second.
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Chemical substances can be chemical elements, chemical compounds, ions or alloys.
A chemical compound is an entity consisting of two or more atoms, at least two from different elements, which associate via chemical bonds.
A chemical element or element is a species of atoms having the same number of protons in their atomic nuclei.
An alloy is a mixture of metals or a mixture of a metal and another element.
Chemical substances are often called 'pure' to set them apart from mixtures.
In chemistry, a mixture is a material system made up of two or more different substances which are mixed but are not combined chemically.
A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory.
A laboratory is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed.
Other chemical substances commonly encountered in pure form are diamond, gold, table salt and refined sugar.
Common salt is a mineral composed primarily of sodium chloride, a chemical compound belonging to the larger class of salts; salt in its natural form as a crystalline mineral is known as rock salt or halite.
Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice.
Sugar is the generalized name for sweet, short-chain, soluble carbohydrates, many of which are used in food.
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
Chemical substances exist as solids, liquids, gases or plasma, and may change between these phases of matter with changes in temperature or pressure.
A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a constant volume independent of pressure.
Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.
A temperature is an objective comparative measure of hot or cold.
Chemical substances may be combined or converted to others by means of chemical reactions.
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another.
Other forms of energy, such as light and heat, are matter, and are thus not "substances" in this regard.
In physics, heat is energy that spontaneously passes between a system and its surroundings in some way other than through work or the transfer of matter.
In physics, energy is a property of objects which can be transferred to other objects or converted into different forms.
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.