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The Particle Theory. Ch. 2. The Particle Theory. More than 2000 years ago, a Greek philosopher Democritus suggested that matter was made of tiny particles too small to be seen.
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The Particle Theory Ch. 2
The Particle Theory More than 2000 years ago, a Greek philosopher Democritus suggested that matter was made of tiny particles too small to be seen. He thought if you kept cutting a substance into smaller and smaller pieces, you would find the building blocks of matter. Democritus “the Laughing Philosopher” 400 BCE
Four Principles of the Particle Theory • All matter is made of tiny particles. • All particles of one substance are the same. - Different substances are made of different particles. • The particles are always moving. - The more energy the particles have, the faster they move. • There are attractive forces between particles. - These forces are stronger when the particles are closer together.
Two Categories of Substances The particle theory helps to explain two categories of substances that are encountered in chemistry. Category 1: Pure Substances - contains only one kind of particle - Types: elements and compounds Category 2: Mixtures - contains two or more different pure substances - Types: homogeneous and heterogeneous mixtures
Category 1: Pure Substances Type 1: Elements – pure substances that cannot be broken down into simpler substances - Examples: think Periodic table (oxygen, hydrogen) Type 2: Compounds – pure substances that contain two or more elements - Examples: Water (H2O), sugar (C6H12O6)
Category 2: Mixtures Type 1: Homogeneous (also known as solutions) – may be made up of solids, liquids or gases - this mixture is uniform (the same) throughout - Examples: air, alloys, kool aid, white vinegar, orange juice without the pulp Type 2: Heterogeneous – see each part easily, separated physically - this mixture is not uniform throughout - Examples: pizza, garbage, beach sand, vegetable soup
Atoms - each atom is made of one type of element - the periodic table of elements has 118 elements • Molecules - contains two or more atoms C4H8 – contains 4 carbon atoms and 8 hydrogen atoms
Classification of Matter Concept Map (ho-oh)Homework Assignment #1: p. 44-47 #1, 3, 4