# 1.2 Properties and Changes of Matter 4 States of Matter - solid, liquid, gas, 4 th state – plasma.

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1.2 Properties and Changes of Matter 4 States of Matter - solid, liquid, gas, 4 th state – plasma

What are Physical Properties? Physical properties – characteristic of matter that does not change example: melting point, color, density, state of matter (solid, liquid or gas). Density - the amount of matter (mass) compared to the amount of space (volume) the object occupies

Density is a physical property of matter that expresses a relationship of mass to volume. The more mass an object contains in a given space, the more dense it is. It’s a constant for that substance (a number that does not change) Example: Density of Gold = 19.30 g / cm 3 Question: If you cut a brick of gold in half would the Density still be 19.30 g/cm 3 ? Yes…. Why? Ratio: cut mass in half – you are also cutting the volume in half

Formula: Density = mass/volume D = m / V The unit for mass is grams (g) or (kg), and the unit for volume is mL or cm 3 usually, So, the units for Density are g/mL, or g/cm 3

Common Densities  Density of water is 1.00 g/ml  The density of a material varies with temperature  Usually, if temperature increases – Density decreases.  Exception: Ice

Physical Properties of Matter: 1) State of matter (solid, liquid or a gas) 2) Density (D = M/V) 3) Malleability - ability to bend 4) Ductile – ability to be drawn out into thin wires 5) Melting point, boiling point, texture, color, odor

Physical Change – a change in matter that does not change the identity of individual substance. Phase Changes are Physical Changes Example: ice melting to water - Substance is still H 2 O

Clues for Physical Changes: 1) Change in shape – dissolving, cutting in half 2) Phase changes – liquid to gas, melting etc

Chemical Properties and Changes Chemical properties –are characteristics of a material that become evident when the material undergoes a chemical reaction or chemical change. Chemical Change - is any change that results in the formation of new chemical substances. Chemical Reactions describe how a substances change into other new substances. Ex: rusting of iron, leaves changing color, burning flame, combustion of gasoline in a car engine.

Chemical Properties 1) Ability to support burning – Oxygen gas In a Chemical Change, Matter is neither created nor destroyed: “Law of conservation of mass and energy” 2 Mg + O 2 ----  2 MgO

2) Reactivity – also a chemical property Ex: rusting, flammability

Clues Chemical Changes: 1) Bubbles – gas forming 2) Color Changes 3) Heat changes – warm or cold Chemical changes involve a change in energy Energy = ability to do work Energy is either added or taken away. Exothermic Reaction a reaction that releases energy (heat energy). ‘Exo’ – out; ‘thermic’ - heat The container in which an exothermic reaction is taking place will feel hot.

Endothermic Reaction – reaction that takes in energy or (heat). Endo = “into” - The container will feel cold.

Density Formula Wheel Formula wheels make it easy to solve density problems. Cover the property you are trying to find, and do what is left over. To find density, cover the word density. You have mass over volume remaining. So divide mass by volume to find density! Mass densityvolume

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