4Pure Substance Elements Matter that can not be broken down into simpler substances under normal lab conditionsContains only one kind of atomAtom MoleculeElements (symbols) Na, Au, CWhere can you find a list of all the elements?
5Pure Substance Compounds Can be separated into elementsComposed of two or more elements that combine in a chemical reactionCombine in a fixed proportionExamples – NaCl, H2O, Fe(NO3)3++
6Which are elements and which are compounds? Compounds contain more than one element. They always have the same composition, regardless of source (law of constant composition; law of definite proportions).
7Mixtures Granite A blend or combination of two or more pure substances Not chemically combinedComposition of mixtures is variableGranite
8Mixtures Heterogeneous A heterogeneous mixture is one that does not blend smoothly throughout and in which the individual substances remain distinct.Mixture with visibly different parts.Sand + waterSalt + PepperM & M’s
9Mixtures HomogeneousA homogeneous mixture has constant composition throughout; it always has a single phase.Mixture with no visibly different parts.Sea water: H2O + NaClAir: N2 + O2 + CO2
10Practice Classifying Matter Make a list of 3 things (and their parts) found in the classroom. Classify these assolid, liquid, or gaspure substances or mixtureshomogeneous or heterogeneouselements or compoundsBe prepared to share your classifications?
11Classify Draw a picture that represents a pure compound. mixtures pure substanceselementscompoundsDraw a picture that represents a pure compound.
12ClassifyClassify each of the following as, a homogenous or heterogeneous mixture, pure substance; element or compound.CH4 (methane gas)KMnO4 (potassium permanganate)Co (cobalt)Al + H2O (aluminum and water)Draw atomic level pictures of each substance.
13Law of Definite Proportions (% By Mass) The mass of the compound is equal to the sum of the masses of the elements that make up the compound.The ratio of the mass of each element to the total mass of the compound is a percentage called the percent by mass.
14Review Questions Identify each of the following as an example of a homogeneous mixture or aheterogeneous mixture.A. a pile of rusty iron filingsB. 70% isopropyl rubbing alcoholC. SaltwaterD. Gasoline
15Review Questions Identify each of the following as an example of an element or a compound.A. sucrose (table sugar, C6H12O6)B. the helium in a balloon (He)C. baking soda (sodium bicarbonate, NaHCO3)D. a diamond (carbon, C)
16Review Questions A 134.50-g sample of aspirin is made up of 6.03 g of hydrogen, g of carbon,and g of oxygen. What is thepercent by mass of each element inaspirin?
17Review Questions A 2.89-g sample of sulfur reacts with 5.72 g of copper to form a blackcompound. What is the percentagecomposition of the compound?
18Calculate the % mass of each element in C6H12O6 Atomic mass of C = 12, H=1, O=16