Chemistry 1211: Chapter 1 Book Notes
Chemistry 1211: Chapter 1 Book Notes 1211
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This 5 page Class Notes was uploaded by Caroline Holt on Sunday August 14, 2016. The Class Notes belongs to 1211 at University of Georgia taught by Jay Agarwal in Fall 2016. Since its upload, it has received 130 views. For similar materials see General Chemistry 1 (CHEM 1211) in Chemistry at University of Georgia.
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Date Created: 08/14/16
Chemistry 1211: Agarwal Chapter 1 Book Notes 1 What is Chemistry? 1.1The Scale of Chemistry Chemistry: the study of matter, its transformations, and how it behaves Matter: any physical substance that occupies space and has mass o Matter consists of atoms, molecules o Most chemical transformations take place at the atomic, molecular level Macroscopic scale: matter that can be seen with the naked eye Atomic scale: (also called nano, molecular scale) used when describing individual atoms or molecules o Observations are made on the macroscopic scale o Descriptions and explanations of chemical processes are made on the atomic level o Macroscopic scale observations explain atomic scale properties 1.2Measuring Matter o Being sure to make precise measurements before and after an experiment reveals information about the chemical composition 2 Classification of Matter 2.1Classifying Matter on the Atomic Scale Properties: collection of characteristics used to describe matter o A fundamental property of matter is the composition: specific types of atoms or molecules that make up the matter Element: simplest type of matter; a pure substance that cannot be broken down into simpler substances Atom: smallest indivisible unit of an element o An element is comprised of atoms ONLY of that element (Aluminum only has aluminum atoms) o To view atoms, scientists use scanning tunneling microscopy (STM) o Atoms of different elements have different sizes o An element MUST consist of the same atoms, even if there are multiple (O2) Chemical compound: substance formed when 2 or more elements are combined in a defined ratio o Compounds can be broken down into simpler substances Molecules: collections of atoms that are held together by chemical bonds 2.2Classifying Pure Substances on the Macroscopic Scale Pure substance: contains only one type of element or compound and has a fixed chemical composition o Has characteristic properties, measurable qualities that are independent 0f the sample size Physical properties: properties of a chemical substance that DO NOT change the chemical composition of the substance when they are measured o Examples of physical properties: Physical state Color Viscosity (resistance to flow) Opacity Density Conductivity Melting, boiling points States of matter: refer to the physical state of a material (solid, liquid, gas) o The macroscopic properties of the states of matter are directly related to the arrangement and properties of particles at the atomic level Solid: dense material with a defined shape o At atomic level, atoms and molecules are packed close together with no rearrangement Liquid: dense, flows, takes shape of container o Atoms, molecules are close together but move more and can flow past one another Gas: no fixed shape, volume o Atoms, molecules spaced widely apart and move rapidly past one another o Do not strongly interact with one another, move freely until they collide with one another or with walls of a container Melting point: the temperature at which solid is turned into a liquid when energy is added to a solid Freezing point: temperature where liquid turns to a solid (same temperature as melting point) Boiling point: temperature at which liquid is converted to a gas o Melting, freezing, boiling points are measured in Celsius or Kelvin o Not all substances can exist in all 3 states of matter Physical change: change in the physical property of a substance o May change appearance or physical state, do not change chemical composition Chemical properties: the properties that involve a chemical change in the material and often involve a substance interacting with other chemicals Chemical change: involves a change in the chemical composition of the material o Flammability is a chemical change because when something burns, the chemical composition changes 2.3Classifying Mixtures on the Macroscopic Scale Mixture: substance or compounds that have not reacted chemically o Relative amounts of each component in the mixture can vary Homogeneous Mixture: a mixture in which there is a constant composition throughout the material Heterogeneous Mixture: mixture in which the composition is not uniform o You can see individual components o Homogeneous, heterogeneous mixtures can usually be physically separated into individual components o Mixtures have physical, chemical properties that depend on the composition of the mixture 3 Units & Measurements 3.1Scientific Units & Scientific Notation SI Units: the units that are used in scientific measurements across most countries Base Units Length Meter m Mass Kilogram Kg Time Second s Electric Current Ampere A Temperature Kelvin K Amount of a Substance Mole Mol Luminous Intensity Candela Cd Derived Units 3 Volume n/a m 3 Density n/a Kg/m Energy n/a J (Joule) Common Prefixes: Mega M 106 3 Kilo K 10 Deci d 10-1 Centi c 10-2 -3 Milli m 10-6 Micro µ 10 Nano n 10-9 Pico p 10-12 Scientific notation: rexresentation of numbers that are very large or very small o Examples: N x 10 o 13433 = 1.3433 x 10 4 o 0.0058 = 5.8 x 10-3 3.2SI Units: Base Units & Derived Units Length: longest dimension of an object o SI Unit: meter: m Mass: measure of the quantity of matter in an object o SI Unit: kilogram: kg o 1 kg = 2.2 lbs Temperature: relative measure of how hot or cold a substance is o Measured using Celsius, Fahrenheit, or Kelvin o How to change between Celsius, Kelvin: T(C) = T(K) – 273.15 T(K) = T(C) + 273.15 o How to change between Celsius, Fahrenheit: T(F) = 9/5 [T(C)] + 32 T(C) = 5/9 [T(F)] - 32 Absolute zero: 0 K, the lowest possible temperature Volume: amount of space that a substance occupies o SI Unit: m : meters cubed o More common unit: liter: L o 1 mL = 1 cm 3 Energy: capacity to do work, transfer heat o SI unit: Joule: J o Common unit: calorie o 1 calorie = 4.184 Joules o 1 Calorie = 1000 calories Density: physical property that relates the mass of a substance to its volume D = m/v o Density of solids: g/cm o Density of liquids: g/mL o Density of gas: g/L o Density changes with temperature because volume fluctuates with temperature 3.3Significant Figures, Precision, and Accuracy o When using a non-digital measuring device, always estimate to the rightmost digit Significant Figures: certain and uncertain digits in a measurement o Significant Figures Rules: 1. All non-zero digits, zeros between non-zero digits are significant 2. In numbers containing a decimal point a. All zeros at the end of the number are significant b. All zeros at the beginning of the number are NOT significant 3. In numbers without a decimal point, all zeros at the end of the number are not significant o When calculating with significant figures, the final calculation is no more certain than the least certain measurement o The answer has the same number of significant figures as the measurement with the fewest number of significant figures Precision: how close the values in a set of measurements are to one another Accuracy: how close a measurement or set of measurements is to the real value 4 Unit Conversions 4.1Dimensional Analysis Conversion factor: an equality written as a ratio Dimensional analysis: method used to change the units of a quantity without changing the amount o Original value is multiplied by the conversion factor 4.2Unit Conversions Using Density o D = m/v o Use density to convert between units of mass and volume
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