topic 1
first two points of particle model of matter and what they help explain
- all matter is made of tiny particles
- all particles in a substance are the same; different substances are made from different particles
these points help understand that matter is made of particles
element (pure substance¹)
- cannot be broken down into any simpler substance
- eg: iron, gold, oxygen
colloid and emulsion (mixture⁴)
- cloudy mixture
- particles too small to be filtered out easily
- emulsions are colloids in which liquids are dispersed in liquids
solid to gas
gas to solid
- sublimination
- deposition
clues to help decide if chemical change occured
- change in color/odor
- formation of gas (bubbles) in liquid
- formation of solid (precipitate) in liquid
- release or absorption of energy (heat)
- only guarantee: new substance formed
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- there are attractive forces among particles (can be weak or strong)
- particles are always moving; more energy = more speed
- particles have spaces between them (state of matter determines how large or how small the gaps are)
these points help explain density and how matter behave with temperature changes
compound (pure substance²)
- combination of two or more elements in fixed proportions
- eg: water, salt, sugar
what determines whether a mixture is a solution, colloid or suspension
- size of particles
- solubility
- mixing ability (miscibility)
solid to liquid
liquid to solid
- melting
- freezing
physical propery
any property that can be observed without forming a new substance
- color
- smell
- boiling point
- ductility
- solubility
- texture
- state
- hardness
- crystal shape
- density and conductivity (electrical and heat)
- luster
- melting point
- malleability
- viscosity
solid
- definite shape and volume
- particles move only a little
- strong attractive forces holding them in fixed positions
solution: homogenous (mixture¹)
- contain particles of different substances
- each substance in mixture isn't clearly visible
- substance dissolved in water = aqueous solution
liquid to gas
gas to liquid
- evaporation
- condensation
chemical property
any property describing how a substance reacts with another substance when forming a new substance
- reaction with acids
- reaction with water
- toxicity
- ability to burn (combustibility)
- behaviour in air
- reaction to heat
- stability
liquid
- take shape of their containers (definite volume)
- particles move more freely
- strong attractive forces
mechanical: heterogenous (mixture²)
- each substance in mixture clearly visible
- eg: blood, soil, concrete
physical change
when a material changes form but not composition
eg: change of state
gas
- fill any container they're in (no matter space/volume)
- weak attractive forces
- particles move a lot more, constantly and randomly
suspension (mixture³)
- cloudy mixtures
- small particles are held (suspended) with another substance (can be filtered out)
chemical change
occurs when two or more substances react, creating one or more new substances (often permanent)
eg: combustion