Get the box of Stuff Wood, steel, aluminum, melamine Properties of Materials Goal: Students will be able to describe various physical properties that materials have Discussion differentiate between chemical and physical properties At your tables list examples of chemical and physical properties. I will call on each table and make a list of all the ones we can think of. Chemical Properties how a material interacts with another material “social” behavior response to other matter (or lack of response) reactions Chemical Properties Examples: burning reaction with acid reaction with water corrosion/rusting/oxidation others???? Physical Properties characteristics it possesses by itself “personal” traits response to energy (in and of itself) Physical Properties color size texture melting point boiling point solubility luster density magnetism odor viscosity crystalline structure Physical Properties Electrical properties conductor or insulator Optical properties – response to light index of refraction – bending of light transparent – light passes through translucent – some light passes through but no distinct image opaque – no light passes through Physical Properties Thermal properties – response to heat conductivity specific heat – how much energy it takes to change temperature thermal expansion – example: iron wire demo Mechanical Properties subgroup of physical response to force or stress force – a push or pull stress – force causing a deformation or distortion (force per unit area) Mechanical Properties Examples workability malleability – can be flattened ductility – can be drawn into wire (stretched), bent, or extruded Mechanical Properties Examples brittleness breaks instead of deforming when stress is applied hardness resistance to denting or scratching Mechanical Properties Examples elasticity ability to return to original shape after being deformed by stress rubber ball or piece of elastic plasticity retains new shape after being deformed by stress wet clay ball or piece of saran wrap Some of the properties At your tables you will find some signs with different physical properties. Go around between tables and answer the questions on a separate piece of paper. Index of Refraction Question. What two materials here have a similar index of refraction? (the three materials are glass, HDPE, and mineral oil) Electrical conductivity What materials here are non-conductive electrically? (the materials are brass, copper coated steel, wax, glass and carbon fiber) Hardness Which material here is the hardest? (Pine and Melamine) Mechanical Properties Examples toughness ability to absorb energy resistance to fracture strength resistance to distortion by stress or force several types: tensile, compressive, torsional, bending, shear Types of Stresses/Forces Tension pulling examples: tug-of-war, slingshot Compression pushing together or squeezing examples: bed springs, can crusher, bench vise straight line = elastic region curved line = plastic region Ceramic or glass stress metal polymer strain City of Materials http://www.cityofmaterials.com General Classes of Materials Polymers Ceramics Composites Metals and Alloys Metals and Alloys Wood and Wood Products Free write On a piece of paper please describe various physical and chemical properties that material's have. If you can include how you could test those physical properties.