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Chemistry is the study of matter, which is anything that has mass and takes up spaces. Changes in matter is best described as physical properties, can be observed without changing the substance into another substance, and chemical properties, a substance that describes it's ability to change into other substances. An example of a physical property is melting point and flexibility. An example of a chemical property is burning and rusting.
Chemical changes may also occur when bonds break and new bonds are then formed. As a result of this, a new substance is formed. Something you can look for in physical properties are changes in color and if gases are produced from solids or liquids.