Chemical and Physical Properties and Changes Learning Intentions 1. I can distinguish a chemical property from a physical property. 2. I can understand materials can be changed through chemical and physical processes. 3. I can understand why we would want to change the physical properties of an object. 4. I can say some natural processes that involve chemical and physical changes. What are properties All substances have properties that we use to identify them •Orca- Black and white, white eye patch, big teeth, large marine mammal •The more properties we know, the better we can identify something •There are two types of properties • Physical • Chemical Physical Properties •Description of an object •Can be determined by our five senses •Include: size, shape, color, texture etc. • Melting point and freezing point (melting point of water vs plastic vs metal) •Physical properties can be changed, sometimes permanently and sometimes irreversibly • What are some examples? Chemical Properties •Are the change of one type of matter into another type of matter •Are determined by a substances ability to react with different substances •Characteristics of a material that can only be observed and measured during a chemical change (NOT WHEN THE MATERIAL IS NOT CHANGING). • You cannot see or feel the chemical properties. • Something (chemical change) must happen to be able to see the chemical properties Examples of Chemical Properties •Ability to react with air: rust, tarnish, corrode, rot •Ability to catch fire: flammability (wood vs paper) Physical vs Chemical Properties C AN YOU N AME S OME D I F F EREN T C HEMI C AL AN D PHYS I C AL PROPERT I ES ? Physical or Chemical Property? Ability of gun powder and fire to explode. Chemical Property Physical or Chemical Property? The color of a sunset. Physical Property Physical or Chemical Property? The ability of a nail to rust. Chemical Property Physical or Chemical Property? The shape of a leaf. Physical Property Physical or Chemical Property? The ability of wood to burn. Chemical Property Physical or Chemical Property? The hardness of a diamond. Physical Property Physical or Chemical Property? The volume of your coke. Physical Property Physical or Chemical Property? The mass of two camels. Physical Property Physical Changes What is it? •Matter undergoes a physical change the material stays the same • The physical appearance of an object changes •Chemically substance is the same •When a physical change occurs the following can change position, size, shape, volume and phase of matter Physical Change Examples •Changing phases- melting, freezing, evaporating •Changing size or shape •Mixing of substances- mixing of cool aid and water Visually seeing Physical Change Physical property changes could include a change in: •Texture •Shape and size •Colour •Odor •Volume, mass, weight, density Chemical Changes What are they? • Changes matter undergoes when it becomes new or different matter. • Occurs when atoms making up matter rearrange •New substance has completely different properties Chemical Change Examples •Production of light- fireworks • A chemical change occurs when fireworks are used. Fireworks are made of metals such as magnesium and copper. These change chemically as they light up the sky. •Rust •Tarnish •Burning •Cooking •Digesting Evidence of Chemical Changes Signs a chemical change occurred include: •Colour change •Production of gas (Bubbles, fizzing, smoke) •Foaming •Light production, sparks, explosions, glowing •Temperature changes •Odor •Formation of a precipitate (solid, cloudy/ foggy solution Chemical vs Physical Changes Now you try With your group, locate a paper and some markers. You may draw, write, colour etc. the following: BE CREATIVE! Who has the strangest/ coolest answer? 1- Provide examples of physical change (2 minutes) 2- Provide examples of chemical change (2 minutes) 3- Regroup as a class. What did your group come up with? Which was easier? Why? Class Discussion PHYSICAL CHANGES CHEMICAL CHANGES Physical or Chemical Change? Water evaporates from the ocean. Physical or Chemical Change? The yolk of an egg, which contains sulfur, causes tarnish to form on silver. Physical or Chemical Change? The ice on a lake melts to become water in the lake. Physical or Chemical Change? Charcoal in a fire turns to ash after several hours. Physical or Chemical Change? A pencil is sharpened in a pencil sharpener, leaving behind shavings. Physical or Chemical Change? A battery makes electricity to turn on a flashlight. Physical or Chemical Change? A bicycle rusts when left in the rain. Physical or Chemical Change? A shirt is accidentally torn in the washing machine. Physical or Chemical Change? A log is split in two by an axe.
