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properties of matter. Physical and chemical properties and changes. Chemistry: big ideas. The use of elements and compounds has both positive and negative effects on society and the environment
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properties of matter Physical and chemical properties and changes
Chemistry: big ideas • The use of elements and compounds has both positive and negative effects on society and the environment • Elements and compounds have specific physical and chemical properties that determine their practical uses. • What does that mean? • Individual characteristics of substances determine how they are used.
Matter • Everything is made of matter. • Your desk • Your shoes • Your lunch • To determine what type of matter something is we use our senses to make observations of its properties. • 5 senses? • Sight • Smell • Touch • Sound • Taste
Matter • Knowing the properties of matter means knowing how to handle it safely- especially when something goes wrong. *WHMIS • Tell me about this: • All matter has both physical and chemical properties.
Physical properties • Characteristics of a substance that are observed with the senses • Can be observed or measured without changing the composition of the substance • The boiling point of water is 100°C • The melting point of water is 0°C • Can be measured without breaking the molecules apart into hydrogen atoms and oxygen atoms • There are 2 types of physical properties….
Physical properties • Qualitative: • Characteristics that can be described but not measured (i.e. no numerical information) • Ex: the solution is an opaque, dark blue colour • Quantitative: • Characteristics that can be measured numerically • Data represented with numbers • Ex: We have 238 ml of the solution
Physical properties Qualitative
Physical properties Quantitative
Characteristic Physical properties • Physical properties can be used to identify a substance: • Eg) The specific temperature at which a substance changes state is a characteristicphysical property • Melting point: temp at which a solid turns into a liquid • Boiling point: temp at which a liquid turns into a gas • Density – Substances have a specific density ratio
Water has very unique physical properties: Can exist in 3 states at the same time Unusually high boiling point Temperature moderation Very soluble! Can dissolve a large variety of chemical substances Liquid is more dense than solid Water's Unusual Properties
Chemical properties • Describe the ability of a substance to react with another substance and form a new substance • Eg. Ability of copper to turn green (oxidizing) is a chemical property
Reactivity A substance’s tendency to react to different substances is a chemical property Reaction with Water Sodium explosion http://www.youtube.com/watch?v=MTcgo46nxNE Calcium carbide light http://www.youtube.com/watch?v=thkgrwGgALw Reaction with Oxygen Iron rust Combustion fire Reaction with acids or bases Baking soda and acid produce CO2 makes dough rise http://www.youtube.com/watch?v=Sgr9gery9dY
Physical Changes Objects do not change their chemical nature Physical properties change - texture, shape, size, colour, odour Eg. Baseball bat Eg. Sugar water
Chemical Changes Atoms combine to form new molecules One or more of the following indicates a chemical change: Change of colour Gas produced Energy released or consumed Precipitate is formed
Physical change think… Change in shape Change in appearance Chemical change think … Burning Cooking Rusting Film processing [Was there production of a new substance?] Physical or Chemical change?
homework Using the tables in your notes, add an everyday example of each property