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Properties of Matter. Physical Properties. Characteristics that can be observed without changing the identity of the substance. Physical properties help identify substances. Observations of Physical properties. Use senses to observe physical properties
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Physical Properties • Characteristics that can be observed without changing the identity of the substance. • Physical properties help identify substances
Observations of Physical properties • Use senses to observe physical properties • Can observe the state of something (solid, liquid, or gas)
Measuring Physical Properties • Melting point- substance changes from a solid to a liquid. • Boiling point- substance changes from a liquid to a gas • Others: strength, hardness, magnetism, ability to conduct electricity, density
Chemical Properties • Describes how a substance changes into a new substance • Can happen by combining with other elements or breaking down • Generally not easy to observe
Examples of Chemical Properties • Flammability –the ability to burn • Reactivity-the capability of a substance to combine with another substance • Ex. Iron combining with oxygen
Physical Changes • Affects one or more physical properties of a substance without changing the identity of a substance. • Ex. melting, cutting, crushing, dissolving
Chemical Change • Happens when one or more substances are changed into entirely new substances that have different properties • Ex. a battery dying, leaves changing colors, rust • Chemical changes can not be reversed by physical changes! • Ex. unbaking bread
Clues for chemical changes • Odor • Change in color • Fizzing or foaming • Production of sound, light, or heat
Which is which? • Identify which changes are physical and which are chemical
Breaking down mixtures and compounds • Mixtures can be separated by physical changes • Ex. picking of ingredients of a pizza or heating things with different boiling points • Compounds must be broken down by chemical changes • Electric currents can be used to break compounds down or opening a soda