 Chemistry – studies matter and the physical and chemical changes it undergoes  Branches of study include: ◦ Organic – carbon compounds (DNA, etc) ◦ Inorganic – non carbon cpds (medicines,etc) ◦ Physical – matter/energy changes (atoms) ◦ Analytical – material makeup (geometry of atoms) ◦ Biochemistry – chemistry of living things ◦ Theoretical – use of physics to understand chemical phenomena (quantum chemistry)

 Matter- anything that has mass and volume  Atom- smallest unit of an element that keeps the properties of element  Element- pure substance made of only one type of atom  Compound- substance made of 2 or more types of atoms that are chemically bonded  Molecule- type of compound in which bonds are covalent bonds

 Element ◦ Composed of identical atoms ◦ Cannot be made simpler by chemical or physical means ◦ EX: copper wire, aluminum foil

 Compound ◦ Composed of 2 or more elements in a fixed ratio that are chemically combined ◦ Able to be separated by chemical means ◦ Properties differ from those of individual elements ◦ EX: table salt (NaCl)

 Variable combination of 2 or more pure substances. ◦ Not chemically combined and can be separated through physical means HeterogeneousHomogeneous

 Homogeneous (solutions) ◦ Very small particles ◦ Particles don’t settle ◦ Appear to be the same throughout ◦ Examples: air, brass, salt water  Heterogeneous ◦ Medium/large particles ◦ Particles may/may not settle ◦ Not the same throughout ◦ Examples: concrete, cookie dough

CompoundMixture One kind of piece- Molecules More than one kind - Molecule or atoms Making is a chemical change Making is a physical change Only one kindVariable composition

MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes

 Characteristic properties of matter are used to classify substances  Types of Properties: ◦ Extensive Property  depends on the amount of matter  Ex: volume, mass ◦ Intensive Property  does not depend on amount  Ex: density, boiling/melting point, ability to conduct heat/electricity

 Examples: ◦ boiling point ◦ volume ◦ mass ◦ density ◦ conductivity intensive extensive intensive

 Physical Property ◦ can be observed without changing the identity of the substance. ◦ Mixtures separated using physical properties  Chemical Property ◦ describes the ability of a substance to undergo changes in identity ◦ Chemical reactions are evidence

 Examples: ◦ melting point ◦ flammable ◦ density ◦ magnetic ◦ tarnishes in air physical chemical physical chemical

 Physical Change ◦ Changes the form of a substance without changing its identity ◦ Properties remain the same ◦ Phase changes, dissolving, cutting, bending, etc ◦ Mixtures separated with a variety of techniques (filtering, evaporation, boiling, etc)  Chemical Change ◦ Changes the identity of a substance ◦ Products have different properties ◦ Combustion, production of odors, gases, light, rusting, precipitation, cooking,etc

 Reactants – The substances that react in a chemical change (stuff you start with)  Products – The substances that are formed by the chemical change (what you make).  NEW PROPERTIES  Not easily reversed reactants product carbon + oxygen → carbon dioxide

 Signs of a Chemical Change ◦ change in color or odor ◦ formation of a gas ◦ formation of a precipitate (solid) ◦ change in light or heat

 Examples: ◦ rusting iron ◦ dissolving in water ◦ burning a log ◦ melting ice ◦ grinding spices chemical physical chemical physical

 Exothermic Reaction- reaction that gives off energy (feels warm on outside)  Endothermic Reaction- reaction that uses up energy (feels cold on outside)

EEnergy is always involved when physical or chemical changes occur. EEnergy can be in various forms. ◦ heat ◦ light LLaw of Conservation of Energy. ◦E◦Energy can be absorbed or released in a change, it is not destroyed or created.

 Solids ◦ very low KE - particles vibrate but can’t move around ◦ fixed shape ◦ fixed volume

 Liquids ◦ low KE - particles can move around but are still close together ◦ variable shape ◦ fixed volume

 Gases ◦ high KE - particles can separate and move throughout container ◦ variable shape ◦ variable volume

 Plasma ◦ very high KE - particles collide with enough energy to break into charged particles (+/-) ◦ gas-like, variable shape & volume ◦ stars, fluorescent light bulbs, CRTs

◦ Particles of matter are always in motion. ◦ As temperature increases, so does speed (Kinetic Energy) of particles ◦ KMT evidence exists in the presence of the four states of matter

 Changing from any state to another state involves the addition or removal of energy from the system  Melting, freezing, vaporizing, evaporation, boiling, sublimation, condensation

Solid Liquid Gas Melt Evaporate Condense Freeze

 Groups (aka: families) ◦ vertical columns ◦ numbered 1  18 ◦ have similar chemical properties  Periods ◦ horizontal rows ◦ properties changes consistently across a period

 Metals ◦ an element that is a good conductor of electricity ◦ at room temperature, most are solids ◦ malleable- can be rolled or hammered into sheets ◦ ductile- can be made into wire ◦ high tensile strength- can resist breakage when pulled ◦ most have silvery or grayish white luster

 Nonmetals ◦ an element that is a poor conductor of heat and electricity ◦ many are gases at room temperature ◦ some are solids: usually brittle, not malleable Various nonmetal elements (a) carbon, (b) sulfur, (c) phosphorus, and (d) iodine

 Metalloids ◦ an element that has some characteristics of metals and nonmetals ◦ appear along staricase line ◦ B, Si, Ge, As, Sb, Te ◦ all are solids at room temperature ◦ less malleable than metals but less brittle than nonmetals ◦ are semiconductors

 Noble Gases ◦ generally unreactive gases ◦ in far right column of periodic table