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Changing Matter 2-3 Objectives • > Explain physical change, and give examples of physical changes. • > Explain chemical change, and give examples of chemical changes. • > Compare and contrast physical and chemical changes. • > Describe how to detect whether a chemical change has occurred. Phases of Matter • There are 4 phases of Matter –Solid, Liquid, Gas, Plasma –Molecules are always moving. They can vibrate and they can expand. Molecular movement • Solids – molecules constantly vibrating • Liquids- molecules are spreading • Gases – Molecules are expanding Phases of Matter Matter can change from form to form depending on the amount of energy (heat) is available. Solid to liquid to gas. Ice in a pan melts then begins to boil and turn to steam. Phase changes & Temperature ___________ / / / / / _________________ Phase changes occur at 1 temperature. Physical Changes • Physical changes occur without creating something new. They effect the physical properties of a substance. Such as melting, mixing, or dissolving. If you can change it back it is a physical change. Chemical changes • Chemical changes occur when the composition is changed and something different is created. • You can tell because of odor, bubbles, color changes, sound, heat or light. • Chemical Change Clip Chemical changes • Chemical changes can not be reversed to go back to original state. • Chemical changes can break down compound such as water to create hydrogen and oxygen. Phases of matter • Solids- definite shape and volume –Crystalline- orderly arrangement of atomsdiamond –Amorphous-opposite- gum Phases Cont’d • Liquid- definite volume no definite shape. –Surface tension-force acting on particles at the surface causing droplets to form. Phases Cont’d Gas- no definite shape and no definite volume. Particles expand and spread out. Change in phase/state • Condensation- energy released when gas changes to a liquid • Temperature and state do not change together 100 Energy must be added 90 to separate the particles as ice melts; 80 the same amount of 70 energy is released when water freezes. Energy is absorbed when water vaporizes; the same amount of energy is released when the water vapor condenses. 60 50 Energy Released to condense 40 Energy absorbed To vaporize 30 20 Energy 10 Released to Energy absorbed Solidify 0 –20 0 to melt 20 40 Relative energy 60 80 Temperature (˚C) 100 120 Change in phase/state • Evaporization- energy required to change liquid to gas • Sublimation- energy required to change solid to a gas • States of Matter Clip Kinetic Theory • All matter is made of atoms that act like particles • Particles are always in motion, hotter= faster Kinetic Theory Cont’d • At same temperature heavier particles move slower than lighter particles. Energy • The ability to change matter and the capacity to do work –Kinetic energy – energy of motion –Potential energy- energy of position Energy Cont’d • Temperature- Average kinetic energy. • Amount of particles do not matter • High temperature means high kinetic energy Energy Cont’d –Thermal energy is the total kinetic energy of particles that make up the object. –The bigger the object more T.E. • Conservation of mass and energy– we cannot create or destroy either