UNIT XI Matter and Change

Obj. 1…Pure Substances vs. Mixtures Matter: anything that takes up space and has mass. Matter can be uniform throughout (homogeneous) or non-uniform throughout (heterogeneous) Two categories of matter: Pure substances Pure substances Mixtures Mixtures

Pure Substances: have a definite composition have a definite composition written as symbol or formula written as symbol or formula homogenous (looks same throughout) homogenous (looks same throughout) Obj. 1 cont… (elements or compounds) 1 capital letter 2 or more capital letters Elements:  composed of one type of atom copper wire aluminum foil silver gold

composed of 2 or more elements that are chemically bonded together. composed of 2 or more elements that are chemically bonded together. they can be broken down only through chemical changes. they can be broken down only through chemical changes. Compounds: water Examples… Obj. 1 cont… salt (NaCl) carbon dioxide (CO 2 ) carbon dioxide (CO 2 ) sand (SiO 2 ) sand (SiO 2 ) (different properties than pure elements)

Same elements but two different compounds, each with a definite composition. For example… For example… Obj. 1 cont…

Mixtures:  composed of two or more different pure substances  composed of two or more different pure substances  cannot be identified by chemical formulas  cannot be identified by chemical formulas  can be separated through physical means  can be separated through physical means  can be homogeneous or heterogeneous  can be homogeneous or heterogeneous Obj. 1 cont… heterogeneous mixture homogeneous mixture

solutions, suspensions and colloids solutions, suspensions and colloids Obj. 1 cont… Three types of mixtures: homogenous heterogeneous Three states (phases) of matter: solids solids liquids liquids gases gases ** mixtures can be composed of any combo. of these!

Obj. 1 cont… Pure or Mixture?!?! 1. Kool-aid 2. distilled water 3. tap water 4. chocolate chip cookie 5. oxygen gas 6. atmosphere 7. Glucose (C 6 H 12 O 6 ) mixture mixture mixture mixture pure pure pure

Obj. 2…Homogenous Matter Three classes of homogenous matter: 1. elements 2. compounds 3. solutions pure mixture Obj. 3-4…Classification of Matter Element: Element: cannot be broken down – only 1 type of atom cannot be broken down – only 1 type of atom - one cap. letter Compound: Compound: chemically separated into elements chemically separated into elements - 2 or more cap. letter Mixture: Mixture: variable composition…no formula! variable composition…no formula!

Obj. 3-4 cont… Element, Compound or Mixture?!?! 1. silver 2. pine tree 3. orange juice 4. phosphorus 5. iced tea 6. Acetaminophen (aspirin) C 8 H 9 O 2 N element element mixture mixture mixture compound

Obj. 5…Metals, Non-Metals and Metalloids Metals… conduct electricity conduct electricity lose e- lose e- malleable malleable (can be hammered) (cations) ductile ductile (can be drawn into a wire) lustrous lustrous (shiny) mostly solids mostly solids Nickel (Ni)

Obj. 5 cont… Non-Metals… don’t conduct electricity don’t conduct electricity gain e- gain e- (anions) dull dull (no luster) usually gaseous usually gaseous Metalloids… properties of both metals and non-metals properties of both metals and non-metals friable friable can lose or gain e- can lose or gain e- some conduct electricity some conduct electricity Sulfur (S) Silicon (Si) (shatters easily)

Obj. 6…Organic vs. Inorganic Organic compounds contain carbon (element of life) Organic compounds contain carbon (element of life) Ex… glucose (C 6 H 12 O 6 ) glucose (C 6 H 12 O 6 ) methane (CH 4 ) methane (CH 4 ) ** Exceptions to the carbon rule… carbon monoxide (CO) carbon monoxide (CO) carbon dioxide (CO 2 ) carbon dioxide (CO 2 ) carbonate ion (CO 3 -1 ) carbonate ion (CO 3 -1 ) ** these exceptions and any compound w/out carbon are INORGANIC **

Obj. 7…Heterogeneous vs. Homogenous homogenous substances are completely uniform throughout. homogenous substances are completely uniform throughout. elements elements (cannot distinguish the different parts) compounds compounds solutions solutions heterogeneous substances are non-uniform throughout. heterogeneous substances are non-uniform throughout. (can distinguish the different parts) colloids colloids suspensions suspensions pure mixture mixtures

Obj. 7 cont… homogeneous heterogeneous

Obj. 8…Solutions, Suspensions & Colloids Solutions… smallest particle size (< 1 nanometer meter) smallest particle size (< 1 nanometer meter) homogenous homogenous particles do not settle out on standing particles do not settle out on standing ~ particles can pass through membrane and filter paper does not display Tyndall Effect (scattering of light) does not display Tyndall Effect (scattering of light) Ex…  salt water (salt and water)  unopened soft drink (water, syrup, CO 2 etc…)

Obj. 8 cont… Suspensions… largest particle size (> 100 nanometers) largest particle size (> 100 nanometers) heterogeneous heterogeneous particles settle out on standing particles settle out on standing ~ particles separated by membrane and filter paper does display Tyndall Effect (scattering of light) does display Tyndall Effect (scattering of light) ~ colloid is left after settling Ex…  muddy water  salad dressing

Obj. 8 cont… Colloids… medium particle size (1-100 nanometers) medium particle size (1-100 nanometers) heterogeneous heterogeneous particles do not settle out on standing particles do not settle out on standing ~ particles separated by membrane, NOT filter paper does display Tyndall Effect (scattering of light) does display Tyndall Effect (scattering of light) Ex…  milk  fog

Obj. 9…Tyndall Effect and Brownian Motion The Tyndall Effect can be seen in mixtures whose particles are large enough to scatter light. The Tyndall Effect can be seen in mixtures whose particles are large enough to scatter light. ~ can see a beam of light through the mixture ~ seen in colloids and suspensions

Tyndall Effect…

Obj. 9 cont… Brownian motion is the constant movement of particles in a mixture due to kinetic energy. Brownian motion is the constant movement of particles in a mixture due to kinetic energy. ~ why solutions and colloids don’t settle out.

Obj. 10…Parts of a Solution all solutions are composed of two parts… all solutions are composed of two parts… ~ solute …substance that gets dissolved ~ solvent …substance that does the dissolving ** the solvent ALWAYS occurs in the greater quantity! Ex… salt water… salt water… ~ solute = salt ~ solvent = water