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  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  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, CO 2, H 2 O  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  Pure substances composed of two or more elements that are chemically combined. Ex. NaCl, CO 2, H 2 O  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  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  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  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  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  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