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There are different ways to separate mixtures, for example by filtration, crystallisation, distillation, or chromatography. The method chosen depends upon the type of mixture.

Mendeleev made an early periodic table. In the modern table, elements are put in order of atomic number into periods and groups. Electron arrangements model how electrons are arranged in atoms.

Ionic bonds, covalent bonds and metallic bonds are examples of chemical bonds. The structure and bonding in a substance are modeled in different ways, including dot and cross diagrams.

Carbon atoms can form four covalent bonds. This lets it form many different organic substances, and to exist as diamond, graphite and fullerenes. Different substances have different bulk properties.