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Intro to Chemistry. Chemistry is the branch of science concerned with the characteristics , composition and changes in matter. Matter is anything that has mass and occupies space (volume). Physical States of Matter Four Physical states of matter exist: solid liquid gas plasma.
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Chemistry is the branch of science concerned with the characteristics , composition and changes in matter. • Matter is anything that has mass and occupies space (volume).
Physical States of Matter • Four Physical states of matter exist: • solid • liquid • gas • plasma
Matter exists in three of theses states on Earth: • Solids have a definite shape and a definite volume. • Liquids have an indefinite shape (they take the shape of their container) and a definite volume. • Gases have indefinite shape and indefinite volume (they take the shape and fill the volume of their container). • The fourth state, plasma, results from nuclear fusion reactions which occur on stars i.e. Sun.
Chemical Properties of Matter • Chemical properties are characteristics of a substance that describe its ability to react chemically with other substances to form new products. • E.g. • When copper is exposed to moist air for long periods of time, it turns green (i.e. roof tops in Ottawa Parliament)
Common Chemical Properties of Matter • Reaction with water • Reaction with oxygen • Reaction with hydrogen • Reaction with acids or bases • Reaction with other pure substances • Toxicity • Stability • Combustibility
A physical change – is a change that does not produce a new substance • I.e. ice melting water is formed • A Chemical Reaction – is a change in matter that produces new substances with new properties. • I.e. vinegar + baking soda carbon dioxide
Chemical reactions involve energy. • Some release energy , some store energy • Products = The new substances that are formed are called. • Reactants = the substances that react together. • A chemical reaction can be written as: Reactants Products (the arrow means there was a chemical reaction!!)
Clues that a Chemical Reaction has occurred are: • Fizzing or gas bubbles • Change in color • Heat or light or odour is given off • A precipitate might form • Difficult to reverse
Activity 2.1 • http://www.youtube.com/watch?v=JmzBf3XGsOE • Answer Questions 1, 2
Question 1 Reactants = vinegar, baking soda Question 2 Water freezing is not a chemical reaction. There were no new products made because water can melt, it is only a change of physical state.