The law of Conservation of Mass states that the mass of matter before and after a chemical change remains the same. The number of atoms also remains the same. The only thing that changes is the arrangement of the atoms. For example, the mass of hydrogen and oxygen before they combine to make water is
Like matter, energy can be classified in different ways. For example, energy can either be kinetic or potential. Kinetic energy is energy of motion. Gases are made of molecules that have more kinetic energy than molecules in the solid phase of that substance. For example, water molecules in steam have greater kinetic energy than molecules
Substances can undergo three type of changes: – Physical changes – Chemical changes (also known as chemical reactions) – Nuclear changes (also known as nuclear reactions) In a physical change the appearance (color, shape, etc.) of the substance may change, but the substance will remain the same substance. A phase change is an example of