• Water normally exists as a liquid that pours freely to fill any solid container, and will solidify if cooled, or evaporate if heated
• Properties such as color and taste of characteristics of matter
Purifying Matter
• Mixture – two (or more) kinds of matter that have separate identities
o Easily separated into component parts
o Said to be impure
o Mixtures like salt water or sugar water that look uniform throughout and do not scatter light are called solutions
o Separating solutions like salt water or sugar water by boiling them dry on the stove is called distillation
Characteristics of Pure Substances
• Pure substances have a constant boiling point
• Freezing point – the temperature at which a liquid solidifies
• Melting point – the temperature at which a solid liquefies
Chemical and Physical Changes
• Density – a property of matter that describes its mass per unit volume
• Chemical change – changes that produce a new kind of matter with different properties
• Decomposition – when one kind of matter breaks apart to create two or more kinds of matter
• Physical change – changes that are easily reversed to get the original material back again; do not appear to produce new kinds of matter
Compounds and Elements
• Electrolysis – involves passing an electric current through a substance to make it decompose into new kinds of matter
• Compounds – pure substances that can be decomposed into new kinds of matter
• Elements – elemental building blocks of all kinds of matter; cannot be decomposed
o 109 known elements
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