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Learn about elements, compounds and mixtures in this KS3 Chemistry guide from BBC Bitesize.
Elements combine to form chemical compounds that are often divided into two categories. Metals often react with nonmetals to form ionic compounds. These compounds are composed of positive and negative ions formed by adding or subtracting electrons from neutral atoms and molecules.
Compounds are formed when atoms of different elements react together. Compounds can be decomposed into elements using chemical means. Most pure substances are compounds. Compounds have a chemical formula. The chemical formula is made up from the symbols of the elements in the compound.
Matter can be broken down into two categories: pure substances and mixtures. Pure substances are further broken down into elements and compounds. Mixtures are physically combined structures that can be separated into their original components. A chemical substance is composed of one type of atom or molecule.
A compound contains atoms of different elements, chemically joined together. Compounds form in chemical reactions, and you need other chemical reactions to separate a compound into its...
Today we often use chemical formulas, such as NaCl, C 12 H 22 O 11, and Co (NH 3) 6 (ClO 4) 3 , to describe chemical compounds. But we still need unique names that unambiguously identify each compound. Common Names.
A compound is represented using its chemical formula that represents the symbols of its constituent elements and the number of atoms of each element in one molecule of the compound. Mixtures cannot be represented by chemical formulas.
