Lecture 2: Matter, Elements and Compounds, States of Matter, Physical and Chemical Changes
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Transcript of Lecture 2: Matter, Elements and Compounds, States of Matter, Physical and Chemical Changes
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ELEMENTS AND COMPOUNDS STATES OF MATTERPHYSICAL AND CHEMICAL PROPERTIES AND CHANGES
Lecture for 9/11/2007
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What is matter?
Anything that has mass and volume
Ancient Greece and India – intrigued by the origin of matter and the makeup of the universe
Is there anywhere that doesn’t contain matter?
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States of matter
Solid – holds a particular shape and has definite volume
Liquid – doesn’t hold its own shape but it does occupy a definite volume
Gas – has no definite shape or volume Plasma – exists inside stars and forms
briefly on Earth when electrical sparks separate atoms into their component parts.
Changes in state - Heating or cooling a substances
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Properties of matter
Physical properties Characteristics of a substance that can be
observed without altering the identity of the substance
Chemical properties Characteristics of a substance that cannot be
observed without altering the substance
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Physical and Chemical Changes
Physical changes – changes that don’t alter the identity of a substance
Chemical changes – alter the identity of the substance
Identify the following as physical or a chemical change:
Sugar ferments to form alcohol. Gallium metal melts in your hand. Platinum reacts with hydrogen peroxide
oxygen at room temperature. Leaves turn color in the Fall.
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Identify the following as physical or a chemical change CON’T:
Milk turns sour. Wax is melted over a flame and then
catches fire and burns. You make scrambled eggs. You step on a piece of chalk and it
becomes powdered. You light a candle when the electricity
goes out. Steam from your hot shower condenses
on a cold mirror.
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Law of conservation of matter
Antoine Lavoisier (1743 – 1794)
Matter, like energy, is neither created nor destroyed in any process
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Elements and Compounds
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Distinguishing Between Elements and Compounds
Both elements and compounds are pure substances
Difficult to determine when a more “fundamental” element was reached
Tear apart substances to see if a more simpler element can be reached