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
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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