chemical substances

• Atom The smallest particle of a chemical element that can exists
• Element are made from only one type of atom
• Compound made from two or more elements that are chemically combined
• The law of conservation of mass tells us that the total mass of products=total mass of reactants
• If the leaf turns blue or black it contains starch
• A mixture is a substance made up of two or more different types of particles which have been mixed together but not chemically changed.
• Oxidation is the gain of oxygen
• Reduction is the loss of oxygen
• An example of reduction cn be found in a thermal decomposition reaction.
• Combustion is an exothermic reaction because it releases energy to the surroundings
• Combustion A reaction that use oxygen to burn fuel and release energy.