Elements, Compounds, Mixtures
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Transcript Elements, Compounds, Mixtures
Elements, Compounds, Mixtures
Chapter 4
Elements
Pure substance that cannot be seperated into
simpler substances by physical or chemical
means. Ex. H, C, O, Au
Pure substance - only one type of particle
Each element has its own characteristic
properites: boiling point, melting point,
density, reactivity with acids or other physical
properties
Three Major Categories of
Elements
Metals - shiny, good conductors, malleable
Nonmetals - dull, poor conductors,
unmalleable
Metalloids - semi-conductors, properties of
both
Compounds
Pure substances composed of two or more
elements that are chemically combined. Ex. NaCl,
CO2, H2O
Two elements must react to combine
Each compound has its own properties: boiling point,
melting point, density, color (physical & chemical
properties)
Can be broken down into simpler substances through
chemical changes, but not physical changes
Mixtures
Combo of two or more substances that are
not chemically combined. Ex. Salad, trail
mix
Substances keep their identity
Substances can be physically separated
Common Techniques for
Separating Mixtures
Distillation
Magnetism
Using a Centrifuge
Filtration
Evaporation
Solutions
A mixture that appears to be a single substance,
but is composed of particles of two or more
substances evenly distributed
Homogenous mixture - same appearance and
properties throughout the mixture
Ex. Hot chocolate, Kool-aid, salt water
Heterogenous mixture - different components are
easily seen
Ex. Salad, Trail mix.
Suspensions: Particles are dispersed and will settle out. Ex.
Salad Dressing (oil & vinegar), dirty air, muddy water
Colloid: Particles dispersed, but don’t settle out. Ex. Milk,
Mayonaise, Fog
Solutions: Solute vs. Solvent
Solute - substance that gets dissolved
Solvent - substance that does the dissolving,
insoluable.
Ex. Kool-aid, solute=sugar & solvent=water
Concentration - measures how much solute
dissolves in a solvent (g/mL)
Concentrated: more solute
Dilute: less solute
Soluability
Ability to dissolve in another substance
Expressed in g/mL or solute/solvent
Soluability increases as temperature increases,
except for gases
Three ways to increase speed of dissolving:
Mixing
Heating
Crushing