Why is an element considered a pure substance?

Pure substance are made of only one kind of particles and fixed constant.

Explanation:

Pure substance are combined in fixed ratio into separate by chemical methods into a physical and chemical methods.

Pure substance are the classified by the compounds and elements, that pure substance fixed into melting and boiling points.Pure substance is used to the chemical reaction product, and there are homogeneous nature only one type.Pure substance include that the copper, oxygen and gold, and water or crystals as that used in pure substance.Pure substance are made the single element,and mainly used in uniform composition throughout.Pure substance element are contain the only one atom to perform the substance the physical and chemical.Pure substance elements into similar substance by heat and electricity reactions with other substance.Pure substance compound contain the two or more elements combined in a fixed proportion.Pure substance compound perform the separate by the physical methods, by that the electric chemical methods.Pure substance compound has fixed composition, and it has two elements hydrogen and oxygen in a ratio to combined.