Compounds, Molecules & Mixtures

• Compounds contain two or more elements chemically combined in fixed proportions
• Compounds normally have very different properties to the elements they were made from
• Mixtures are not chemically combined
• Mixtures can be separated by physical separation techniques such as distillation, filtration, crystallisation and chromotography.
• Compounds have to be separated by chemical reactions.
• A molecule has any number of atoms bonded together.
• Physical separation techniques can only be used to separate mixtures, NOT compounds.
• A molecule is a group of 2 or more atoms held together by chemical bonds
• Molecules can be multiple different elements
• Compounds are substances that contain 2 or more different elements held together by chemical bonds.
• Some molecules are also compounds, but only ones that have different elements.
• In compounds, the elements are always found in the same proportions. This means we can write formulas for compounds such as carbon dioxide which is CO2
• In formulas, brackets show that everything within them is the same number as on the outside of the bracket.
• mixtures are 2 or more substances that are not chemically combined together
• mixtures can be easily separated using physical methods