3.3 Mixtures of Matter A mixture is a physical combination of 2 or more substances. A heterogeneous mixture is a physical combination of 2 or more substances where the individual substances remain distinct and 2 or more phases are visible. A homogeneous mixture is a physical combination of constant composition where there is a single phase. Another name for a homogeneous mixture is a solution.

Separating Mixtures Filtration is a method for separating heterogeneous mixtures by passing the mixture through a pouros filter or layer. In filtration, the precipitate is the solid phase that remains in the filter paper, or media, and the filtrate is the liquid portion that passes through. Distillation is a process that uses different boiling points to separate liquids or liquids from solids...as each substance reaches its boiling point, it leaves the mixture and is condensed in an apparatus called a condenser, then it drips away to be collected.

Separating Mixtures (Continued) Crystallization is a process that causes crystals to collect, out of a saturated or super-saturated solution. The crystals are a pure substance that can be collected. Sublimation is the conversion of a solid directly to a gas...gases can be collected and separated in this way, much like distillation.

Separating Mixtures (Continued) Chromatography is a method of separating different components of a mixture based upon different solubilities and different sizes of molecules. Soluble substances dissolved in a gas or liquid, the mobile phase, move through a medium, called the stationary phase. During paper chromatography, molecules that are soluble move with the solvent up the paper...small molecules go far and large molecules move less.

Elements and Compounds An element is the simplest form of matter that cannot be made simpler by physical or chemical means. Elements are represented on the periodic table. Each element has one capital letter so you can count capitol letters in a compound to find out how many different elements are present. Elements are represented on the periodic table. Rows of elements are called periods and columns of elements are called groups. Dmitri Mendeleev set up the original periodic table based on periodic properties or similarities and atomic masses.....the modern periodic table is set up based upon periodic properties and atomic numbers, which represent the number of protons in an atom.

Elements and Compounds (continued) A compound is a chemical combination of 2 or more elements. The properties of a compound are different from the component elements. Compounds can either be ionic (usually a metal and a non-metal) or molecular (usually composed of 2 non-metals.) The law of defininte proportions states that a compound is always composed of the same elements, in the same proportions.

Percent by Mass of a Compound To calculate the percent, by mass, of a compound, look up the element on the periodic table. 2. Add up the gram atomic mass of each element (the decimal number, usually under each element.) in a compound to get a total mass of the compound. 3. Divide the individual element mass by the total mass of the compound, for each element, then multiply by 100%...this will give the % composition for each element. 4. Your answer for % by mass should include the %, by mass, for each element in the compound.

Separating Compounds into Component Elements Electrolysis is a method for separation of compounds into individual elements.(See text pg. 88.)

The Law of Multiple Proportions When different compounds are composed of the same elements, different masses of one element combine with a fixed mass and proportion of the other element(s) that is the same for the compound each time, but each compound has its own unique ratio of masses of the elements. Examples H 2 O and H 2 O 2.

Formulas of Compounds A formula is used to represent each compound...the formula uses element symbols and a sub-number to tell the number of moles of each element. A mole, of an element, is a quantity that represents 6.02 x atoms of the element. The mole is the SI unit of counting used to represent 6.02 x atoms of an element or 6.02 x molecules of a compound.