 Observations ◦ Existing knowledge – ask a question ◦ Do some background research ◦ Qualitative data – information that describes color, odor, shape or some other physical characteristic. ◦ Quantitative data – numerical information; tells you how much, how little, how big, how tall, how fast, etc.  Hypothesis ◦ Testable statement or prediction ◦ A proposed explanation for an observation

 Experiment ◦ A set of controlled observations that test the hypothesis ◦ Need data to support a hypothesis ◦ Independent Variable – variable that you change. ◦ Dependent Variable – variable that changes in response to the independent variable. ◦ Control – a standard for comparison ◦ Produces data ◦ May need to go back and revise hypothesis and start experiment over.

 Data - Analysis ◦ Collected from the experiment and organized, typically in a chart or table. ◦ Used to draw conclusions  Conclusion ◦ A judgment based on the information obtained ◦ Hypothesis can never be proven, so data is always said to “support hypothesis” ◦ If data does not support, hypothesis is discarded or modified ◦ Most hypotheses are not supported but yield new information ◦ Model – a visual, verbal and/or mathematical explanation of experimental data

 Experiments may lead to information that can be reproduced over and over  Theory – an explanation that has been supported by many, many experiments. ◦ States a broad principle of nature that has been supported over time ◦ Still subject to new experimental data and can be modified  i.e. Einstein’s Theory of Relativity

 Law – A relationship in nature that is supported by many experiments. ◦ Same conclusion reached over and over, without exception ◦ It is up to scientists to conduct experiments to explain why these exist  i.e. Newton’s Law’s

 Anything that has mass and takes up space  Mass – a measurement that reflects the amount of matter  Weight – a measure of the amount of matter and the effect of Earth’s gravitational pull on that matter.

 Solid – matter with its own definite shape and volume ◦ Ex: wood, iron, paper, sugar  Liquid – matter that flows ◦ Ex: water, blood, mercury  Gas – matter that flows to conform to the shape of its container and fills the entire volume ◦ Neon, methane, air

StateShapeVolumeCompressible? Solid Definite No Liquid IndefiniteDefiniteNo Gas Indefinite Yes

 A characteristic that can be observed or measured without changing the samples composition. ◦ Density ◦ Color ◦ Odor ◦ Taste ◦ Hardness ◦ Melting point ◦ Boiling point ◦ Solubility

 Extensive Properties ◦ Depends of how much (the extent) matter there is ◦ Ex: mass, length, volume  Intensive Properties ◦ Independent (does NOT depend) of how much matter ◦ Substance can often be identified by intensive property ◦ Ex: density, temperature

 Water boils at 100 o C  There are 50 lbs of sand in a bucket.  Oil is less dense than water.  A piece of copper is 10m long. intensive extensive

 The ability of a substance to combine with or change into one or more other substances ◦ Combustibility  Sodium reacts with water, may combust ◦ Reactivity with other substances  Iron rusts when exposed to oxygen

 Substance (Pure Substance) ◦ Matter that has uniform and unchanging composition ◦ Only 1 type of matter present  Element ◦ A pure substance that cannot be separated into simpler substances by physical or chemical means  Compound ◦ Combination of two or more different elements chemically combined  Mixture ◦ Combination of two or more pure substances in which each pure substances retains its chemical properties

 Sulfur dioxide  Brass (Zn + Cu)  Fluorine  Lemonade w/ pulp  Gasoline  Beach sand Pure substance, compound Mixture, homogenous Pure substance, element Mixture, heterogeneous Mixture, homogenous Mixture, heterogeneous

Matter Pure substancemixture elementhomogeneouscompoundheterogeneous

 Homogeneous Mixture- ◦ Has a constant composition throughout ◦ Single phase ◦ Looks the same throughout ◦ Also referred to as solutions  Heterogeneous Mixture- ◦ Does not blend smoothly throughout ◦ Individual substances remain distinct

 Metals – ◦ Have luster (shine) ◦ Malleable (not brittle) ◦ Ductile (can be drawn into wires) ◦ Conduct heat and electricity  Nonmetals – ◦ Brittle ◦ Poor conductors of heat and electricity  Metalloids – ◦ Have characteristics of both metals and nonmetals

 A homogeneous mixture  Composed of 2 parts ◦ Solvent – substance there is more of  Dissolving substance ◦ Solute – substance that is added to solvent  Dissolved substance

 Alter a substance without changing its composition  Identifying properties remain unchanged ◦ Phase change ◦ Breaking or cutting ◦ Dissolving ◦ Bend ◦ Crumple ◦ Split ◦ Crush

 One or more substances changing into new substances  Different substances formed ◦ Burning ◦ Rusting ◦ Decaying or spoiling ◦ Fermentation ◦ Acid reacting with metal

 Heat gained or lost  Production of a gas  Formation of a precipitate  Color change

 Mass is neither created nor destroyed during a chemical reaction, it is always conserved.  Mass of reactants always equals mass of products. Mass reactants = Mass products

 Regardless of amount, a compound is always composed of the same elements in the same proportion by mass. ◦ Water, H 2 O ◦ Always made of 2:H’s and 1:O no matter how much water you have

 When different compounds are formed by a combination of the same elements, different masses of one element combine with the same relative mass of the other element in a ratio of small whole numbers.  H 2 O vs. H 2 O 2  Water has 2 H’s for every 1 O  Hydrogen peroxide has 2 H’s for every 2 O’s

 Use different properties of substances to separate them ◦ Sand and iron filings ◦ Sand and salt ◦ Sand and water ◦ Water and salt water ◦ Oil in water (immiscible liquids) ◦ Mixture of pigments Remove iron with magnet Add water, dissolve salt, filter sand, evaporate water filter Distill the water Settle and extract less dense liquid Paper chromatography

 Defined unit in a system of measurement that is based on an object or event in the physical world.  Independent of other units.

QuantityBase Unit TimeSecond (s) LengthMeter (m) MassKilogram (kg) TemperatureKelvin (K) Amount of a SubstanceMole (mol) Electric CurrentAmpere (A) Luminous IntensityCandela (cd)

 Unit that is defined by a combination of base units. ◦ Volume – the space occupied by an object.  derived unit – m 3  cm 3 = mL ◦ Density – ratio that compares mass of an object to its volume.

 How can we rearrange this equation if we have the density and volume.

 Kelvin scale, founded by William Thompson who was known as Lord Kelvin. ◦ Water freezes at 273 K ◦ It boils at 373K ◦ The scale is the same as Celsius, just different temperature points  Celsius = Kelvin  Kelvin – 273 = Celsius

 If the density of an object is 2.70 g/cm3 and the mass of the object is 1.65g, what is the volume of the sample?

 An object has a density of 7.7g/cm 3 and a volume of 5 mL, what is the density of the object? m = v x D m = 5 cm 3 x 7.7g/cm 3 = 39 g

 Convert the following: ◦ 357 o C to Kelvin  357 o C = 630K ◦ -39 o C to Kelvin  -39 o C = 234K ◦ 266K to Celsius  266K – 273 = -7 o C ◦ 332K to Celsius  332K – 273 = 59 o C

 Precision ◦ The agreement between measurements. ◦ How close a set of measurements are to each other.  Accuracy ◦ The nearness of a measurement to its actual value. ◦ How close you are to the true value.

 You analyze a sample of copper sulfate and find that it is 68% copper. The theoretical value of copper is 80%. What is the percent error?