Changes

• Chemical Change

  Bonds between atoms or molecules are broken or new bonds between these particles are formed, thus making it difficult to reverse. They occur due to chemical reactions that rearrange the atoms.
• Physical Change

  Reversible change that does not involve altering bonds. Generally to do with changes in shape or size.
• Chemical change

  Change where a new substance is created.
• Reactants

  Substances that you begin with in terms of a chemical reaction.
• Products

  Substances that are produced by a chemical reaction.
• Explosions

  A type of chemical reaction that takes place very quickly, that releases a lot of heat, light and noise.
• Reaction Rate

  A measure of how quickly a chemical reaction occurs.
• Exothermic Reaction

  Chemical reaction that produce energy in the form of heat
• Endothermic Reaction

  Chemical reactions that absorb energy resulting in a decrease in temperature.
• Catalysts

  Increase the rate of a chemical reaction, however, is unchanged after the reaction and thus is not classified as a reactant. An example in the human body is enzymes
• Speeding up a reaction with heat

  Heating a substance adds energy to its particles, making them move more rapidly and collide more frequently. When they collide, bonds between the particles are broken and new ones are more easily formed with particles from other substances.
• Arrangements of atoms

  Elements are only made of one type of atom, but can be arranged in different ways such as single atoms (monatomic), multiple atoms (diatomic) and clusters of atoms (molecules) or lattices.