CHEM109 Chapter 1 Notes
CHEM109 Chapter 1 Notes CHEM 109
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This 4 page Class Notes was uploaded by Hannah Rapp on Tuesday August 30, 2016. The Class Notes belongs to CHEM 109 at University of Nebraska Lincoln taught by Jason Kautz in Fall 2016. Since its upload, it has received 178 views. For similar materials see General Chemistry 1 in Chemistry at University of Nebraska Lincoln.
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Date Created: 08/30/16
Classiﬁcation of Matter • Matter can be classiﬁed as a substance or mixture. • A substance is a form of matter that has a deﬁnite composition and distinct properties o Can be elements or compounds o An element cannot be separated into simpler substances - Consists of atoms/molecules - Diatomics: H 2 N 2 F 2 O 2,I2 , 2 Br 2 - Way to remember diatomics: • Have No Fear Of Ice Cold Beer o A compound is composed of 2 or more elements chemically united in ﬁxed proportions • Classiﬁed according to state of matter o Solids and liquids are in condensed phases o Types of motion in particles: - Vibrational: bonds stretch and bend - Rotational: rotation around X, Y, and Z axis - Translation: movement in a straight line o Solids: - Particles close together - Crystalline solids- highly ordered - Amorphous solids- lack order - Deﬁnite shape and volume - Only vibrational movement o Liquids: - Particles close together (not as close as solid) - Not highly ordered - Forms a surface - No deﬁnite shape, but has a deﬁnite volume - Vibrational movement; some rotational and translational movement o Gases: - Particles further apart - No organizational order - Fills/ expands to ﬁll container - No deﬁnite shape or volume - Compressible - Vibrational, rotational, and translation movement • A mixture is a physical combination of 2 or more substances o Homogenous: uniform throughout - Ex) salt water o Heterogenous: not uniform throughout o Mixture can be physically separated into pure components Properties of Matter • Qualitative: uses words to describe o Ex) it is warm • Quantitative: deals with numbers o Ex) it is 90 degrees • Physical property: observed/measured o Ex) color, texture • Physical change: change in state o Ex) sublimation, vaporization, condensation • Chemical property: interaction between substances o Ex) ﬂammability, boiling point, smell • Chemical change: results in a change in composition o Ex) oxidation, combustion, digestion • Extensive property: deals with amount o Ex) mass, volume • Intensive property: doesn’t depend on amount o Ex) temperature, density • Density: ratio of mass to volume o D=m v o SI unit- kg/m o Other common units: - g/cm (solids) - g/mL (liquids) - g/L (gases) Signiﬁcant Figures Rules • all non zeros are sig ﬁgs o 68.3 ———— 3 • all zeros between non zeros are sig ﬁgs o 101 ———— 3 • leading zeros are NOT sig ﬁgs o 0.012 –——— 2 • trailing zeros WITH a decimal place are sig ﬁgs o 27.00 ———— 4 • trailing zeros with NO decimal place are NOT sig ﬁgs o 2700 ———— 2 SIG FIG PRACTICE 1) 2507 ———— 4 2) 204,300 ———— 4 3) 24.0 ———— 3 4) 5000.0 ———— 5 • Addition and Subtraction with sig ﬁgs: o Least number of decimal places 1 24.37 + 2.336 would have 2 decimal places 26.71 2 104,700.1 – 20.034 would have 1 decimal place 104,680.1 • Multiplication and Division with sig ﬁgs: o Least number of signiﬁcant ﬁgures 1 100 x 204.3 would have 1 sig ﬁg 20,000 2 88.000 x 100,010 would have 5 sig ﬁgs 8,800,900 Scientiﬁc Measurement • The revised metric system is called the International System of Units and was designed for universal use Base Quantity Name of Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electric current Ampere A Temperature Kelvin K Amount of substance Mole mol Luminous intensity Candela cd • Derived SI unit for volume is m • A more practical unit for volume is the liter (L) o 1 dm = 1 L o 1 cm = 1 mL • Density: o If the item ﬂoats, it’s less dense o If the item sinks, it’s more dense Preﬁx Symbol Meaning Example Tera- T 1 x 1012 1 teragram (Tg)= 1 x 1012grams Giga- G 1 x 109 1 gigawatt (Gw)= 1 x 10 watts 6 6 Mega- M 1 x 10 1 megahertz (MHz)= 1 x 10 hertz Kilo- k 1 x 103 1 kilometer (km)= 1 x 10 meter Deci- d 1 x 10-1 1 deciliter (dL)= 1 x 10 liter Centi- c 1 x 10-2 1 centimeter (cm)= 1 x 10 meter Milli- m 1 x 10-3 1 millimeter (mm)= 1 x 10 meter -6 -6 Micro- µ 1 x 10 1 microliter (µL)= 1 x 10 liter Nano- n 1 x 10-9 1 nanosecond (ns)= 1 x 10 s9 -12 -12 Pico- p 1 x 10 1 picogram (pg)= 1 x 10 gram • There are two temperature scales in Chemistry o Celsius Scale (˚C) ―▯Freezing point: 0˚C ―▯Boiling point: 100˚C o Kelvin Scale (K) ―▯Absolute scale ―▯Lowest possible temperature is 0K K=˚C+ 273 Uncertainty in Measurement • Exact number have deﬁned values o 1 kg= 1000 g o 1 dozen= 12 o ∏ • Inexact numbers o ∏=3.14……. • Accuracy: how close a measurement is to the true value • Precision: how closely multiple measurements are to one another Student 1 Student 2 Student 3 0.335 g 0.357 g 0.369 g 0.331 g 0.375 g 0.371 g 0.333 g 0.338 g 0.373 g The true mass is 0.370 g Student 1 is precise, but not accurate Student 2 is neither precise not accurate Student 3 is both accurate and precise
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