* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Why Study Chemistry
Inorganic chemistry wikipedia , lookup
Heat transfer wikipedia , lookup
Artificial photosynthesis wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
Chemical element wikipedia , lookup
Transition state theory wikipedia , lookup
Abundance of the chemical elements wikipedia , lookup
Al-Shifa pharmaceutical factory wikipedia , lookup
Computational chemistry wikipedia , lookup
Chemical industry wikipedia , lookup
Chemical weapon proliferation wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
California Green Chemistry Initiative wikipedia , lookup
Water pollution wikipedia , lookup
Chemical weapon wikipedia , lookup
Thermodynamics wikipedia , lookup
Chemical Corps wikipedia , lookup
Drug discovery wikipedia , lookup
Chemical plant wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Water splitting wikipedia , lookup
Chemical potential wikipedia , lookup
Electrolysis of water wikipedia , lookup
Condensed matter physics wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
Freshwater environmental quality parameters wikipedia , lookup
Molecular dynamics wikipedia , lookup
Registration, Evaluation, Authorisation and Restriction of Chemicals wikipedia , lookup
History of molecular theory wikipedia , lookup
Safety data sheet wikipedia , lookup
VX (nerve agent) wikipedia , lookup
History of chemistry wikipedia , lookup
Chemical thermodynamics wikipedia , lookup
Why Study Chemistry? • To be better informed • To be a knowledgeable consumer • To make better decisions for yourself and society • To learn problem-solving skills • To enhance analytical thinking Chemistry as the “Central Science” • Chemistry = the study of matter and the transformation it undergoes • EVERYTHING is a CHEMICAL – – – – – Table salt = sodium chloride, NaCl Table sugar = sucrose, C12H22O11 Clothes: Wool? Cotton? Polyester? Body: lipids, Proteins, Carbohydrates, DNA/RNA You name it– it’s a chemical! Chemistry as the “Central Science” • Chemistry is the driving force behind many “liberal arts” – Composition of paints? Colors? – Economies of industrial nations • #1 commercial chemical is sulfuric acid– LOTS of uses! • All idustry involves chemical processes – Economies of Developing Nations • Agriculture depends on chemicals as fertilizers, pesticides – Politics and Natural Resources The Study of Chemistry • Chemistry is everywhere! • Matter is everywhere! • Thus, chemistry matters! • Chemistry involves the study of matter – its properties and behavior. • Macroscopic observations are rooted in microscopic structure. Assignment: Chemistry in your major • Find a current news story or historical example that demonstrates the importance of chemistry to your major – For example: chemical resource as a key issue in a political / economic rift; wars fought over chemical resources; etc • Write a 2 paragraph summary on issue and its relevance to your studies Chemistry as the “Central Science” Classification of Matter 4 Physical States: solid, liquid, gas, plasma Solid: Fixed shape and fixed volume; Atoms tightly packed together Classification of Matter Liquid: No fixed shape but maintains a fixed volume Atoms loosely packed together, slide around each other Classification of Matter Gas: No fixed shape or volume Atoms not really associated with neighbors at all Classification of Matter Plasma: mix of subatomic particles with not organization (sun) States of Matter States of Matter Gases, liquids and solids are all made up of microscopic particles, but the behaviors of these particles differ in the three phases. The following figure illustrates the microscopic differences. Microscopic view of a gas. Microscopic view of a liquid. Microscopic view of a solid. States of Matter State Solid Liquid Gas Shape Keeps Shape Takes Shape of Container Takes Shape of Container Volume Compress Flow Keeps Volume Keeps Volume No No No Yes Takes Volume of Container Yes Yes Properties of Matter Physical Properties = characteristics of a material Color Mass Temperature Odor Density Hardness Solubility Conductivity (heat or electrical) Freezing/boiling point Chemical Properties = describe how a material reacts with another type of matter Ability to burn Ability to rust / corrode Ability to make a solution acidic or basic Lack of ability to react with something Properties of Matter • physical – measured without changing substance, e.g. physical state, color, odor, density, boiling point • chemical – describes a substance’s reactivity, e.g. flammability, corrosiveness • extensive – depends on the amount of matter present, e.g. mass, volume • intensive – does not depend on the amount of matter present, e.g. density, color, temperature • Properties: “ The characteristics that give each substance its unique identity “ • Physical Properties: “ Properties that can be observed without changing the identity of a substance “ Color Melting Temperature - a physical change of state Electrical conductivity Density Boiling Temperature - a physical change of state Solubility Hardness Chemical Properties: “ Properties that result in changes in the identity of one or more reactants “ The rusting of iron Hydrogen and oxygen burning to form water The baking of bread The absorption of oxygen by hemoglobin Changes in Matter Physical Changes = a change in a physical property; does NOT change the chemical composition or atomic arrangement of the material – Increase in temperature – Phase changes – Cutting into smaller pieces Chemical Changes = changes that alter the identity of a material, a change in the chemical composition or atomic arrangement of the material – Wood burns in air to produce CO2 and H2O – Cooking an egg (change molecular structure of the proteins, loss of water) – Formation of rust (iron to iron oxide) Changes in Matter: Is it Physical or Chemical? • Properties: “ The characteristics that give each substance its unique identity “ • Physical Properties: “ Properties that can be observed without changing the identity of a substance Color Melting Temperature - a physical change of state Electrical conductivity Density Boiling Temperature - a physical change of state Solubility Hardness continue….. Changes in Matter (cont) • Chemical Properties: “ Properties that result in changes in the identity of one or more reactants “ The rusting of iron Hydrogen and oxygen burning to form water The baking of bread The absorption of oxygen by hemoglobin continue….. Changes in Matter (cont) Chemical Reactions: “ Process in which one or more pure substances are converted to one or more different pure substances “ Reactants: “ Substances that undergo change in a chemical reaction “ Reactants are on the left side of the chemical equation Products: “ Substances formed as the result of a chemical reaction “ Products are on the right side of the chemical equation Reactants Hydrogen + Oxygen Products Water Changes in Matter - Physical & Chemical • Physical Change: “ A change that alters the physical form of matter without changing its chemical identity “ • Chemical Change: “ A change which changes the chemical identity of the substance and creates one or more new substances “ continue….. Changes in Matter - Physical Change •Example of a Physical Change: A Melting Ice Sickle Solid Water Liquid Water continue….. Changes in Matter - Chemical Change • Example of a Chemical Change: The Electrolysis of Water (H2O) Particulate Viewpoint Oxygen Gas Hydrogen Gas Negative Electrode 2H2O Positive Electrode 2H2 + O2 continue….. The Chemical Identity of Water ( H2O ) is changed into the elements Hydrogen ( H2 ) and Oxygen ( O2 ) 24 2.7 Using Chemical Symbols (cont) Chemical Equations: “ Representations of chemical reactions by the formulas of reactants and products “ 2 C (s) + O2 (g) 2 CO At the Macroscopic Level: “ Carbon, a solid plus oxygen gas yields carbon monoxide “ At the Particulate Level: “ Two atoms of carbon plus one diatomic molecule of oxygen yields two molecules of carbon monoxide “ Equation Coefficients: “ Gives the relative amount of each compound involved in the chemical equation “ Balanced Chemical Equations: “ The number of each kind of atom on the reactant side must equal the number of each kind of atom on the product side “ Classification of Matter Matter - Anything that occupies space and has mass (solid, liquid or gas) Heterogeneous Mixture: Non-uniform composition Physically Separable Into Pure Substances: Fixed composition; cannot be further purified Homogeneous Matter: Uniform composition Physically Separable Into Solution: Homogeneous mixture Chemically decomposable Into Compounds: Elements united in fixed ratios Combine Chemically to Elements: Cannot be subdivided by chemical or physical changes 26 The Chemical View of Matter What are elements and chemical compounds made of? What is the difference between a mixture and a pure substance? What is the difference between a chemical and a physical process? What is the basic theme of chemistry? How are symbols for the elements used in formulas and equations to communicate chemical information? continue…. Macroscopic, Microscopic & Particulate Matter • • • • Matter: - “ Anything that has mass and takes up space (occupies volume) “ Matter can be studied on three levels: Macroscopic Level: “ Matter that can be seen with the human eye “ Beach Sand, Trees, Cars, Pen, CD, Mountains, Planets, Galaxies, etc • Length: 101 to 109 meters continue….. Macroscopic, Microscopic & Particulate Matter (cont) • Microscopic Level: “ Matter that is too small to be seen by the naked eye, but can be seen under a • microscope Very small plants, individual bacteria, cellular structures, DNA Molecule, Semiconductors, etc • Length: 10- 6 meters continue….. Macroscopic, Microscopic & Particulate Matter (cont) • Particulate Level: “ Matter too small to be seen with even the most powerful optical microscope “ Particulate matter consists of the tiny particles that make up all matter Molecules, atoms, protons & electron • Length: 10 - 10 meters (1 Angstrom = 10 - 10 meters ) continue….. Elements - The Most Simple Kind of Matter Pure Substance: “Something that with a uniform, fixed composition at the submicroscopic level” Recognized by the unchanging nature of their properties Element: “A pure substance composed of only one kind of atom” Atom: “The smallest particle of an element” Atoms of different elements are different and are shown on the periodic table Each element has a one or two letter abbreviation Hydrogen - H Helium - He Sodium - Na Lithium - Li Microscopic view of the atoms of the Microscopic view of the molecules of the element argon (gas phase). element nitrogen (gas phase). Elements The Periodic Table and the Elements (cont) Main Group Elements Main Group Elements Transition Metals continue…. Inner Transition Elements 34 Chemical Compounds - Atoms in Combination Chemical Compounds: “ Pure substances made of atoms of different elements combined in definite ways” Examples: H2O Water NaCl Sodium Chloride C2H6O Ethanol C6H12O6 Sugar Chemical Compounds (cont) • Compound: “ Any pure substance that can be decomposed by a • chemical change into two or more pure substances • is a compound “ (another definition) • Compounds are made up of elements • Examples of Compounds: continue….. Using Chemical Symbols Chemical Formulas: “ Combinations of the symbols for the elements that represent the stable combinations of atoms in molecules “ Examples: Water H2O Carbon dioxide CO2 Ammonia NH3 Methane CH4 Carbon Tetrachloride CCl4 Subscripts: “ Indicate the relative numbers of atoms of each kind “ Using Chemical Symbols (cont) Structural Formulas: “ Formulas that show the connections between atoms in molecules “ H Ammonia H N H Water H O H H Methane H C H H Microscopic view of the molecules of the compound water (gas phase). Oxygen atoms are red and hydrogen atoms are white. Mixtures and Pure Substances • Homogeneous Sample: “ Matter that has a uniform appearance and • composition throughout “ A mixture of water and alcohol Sugar dissolved in water Gold blended with silver (18 karat gold) The air we breathe - a mixture of oxygen and nitrogen Solutions: “Homogeneous mixtures, either liquid, solid or gaseous” continue….. Mixtures and Pure Substances (cont) Table salt is stirred into water (left), forming a homogeneous mixture called a solution (right) 41 continue….. Mixtures and Pure Substances (cont) Heterogeneous Sample: “ Matter that does not have a uniform appearance and composition throughout “ A mixture of cooking oil and water (two phases develop) Concrete (sand, rock, cement, etc) A mixture of sand, sawdust, iron fillings and water continue….. Mixtures and Pure Substances (cont) Sand and water do not mix to form a uniform mixture continue….. Mixtures: Homogeneous • Same composition throughout sample • Ex- milk, tea, others? Heterogeneous • Different samples of the same mixture have different compositions • Ex- air in the room others? Microscopic view of a gaseous mixture containing two elements (argon and nitrogen) and a compound (water). Classification of Matter Substances vs Mixtures Substance – has a definite or fixed composition – Composition does not vary from sample to sample Mixture – Has a varied composition – Each individual component can be separated by physical means – Ex: salt and pepper, sugar in water, sea water Energy • The “fuel” of the universe • The capacity of something to do work – chemical, mechanical, thermal, electrical, radiant, sound, nuclear • The SI unit of energy is the Joule (J) – Other common units are • Calories (cal) • Kilowatt-hour (kW.hr) • Types of energy: – Potential – Kinetic – Heat • Energy cannot be created nor destroyed (but it does change from one type to another!) Changes in Matter - Energy Energy: “ The ability to cause change or, in formal terms of physics, the ability to do work “ Potential Energy: “ Energy in storage “ There is potential energy in gasoline called chemical energy Chemical energy is release as heat and light when it burns Chemical energy can also be released as electrical energy Kinetic Energy: “ Energy in motion “ Examples are - Muscle in movement, a rocket in flight, inflation of a car air bag during collision Heat & Temperature • Temperature is _____. – how hot or cold something is (a physical property) – related to the average (kinetic) energy of the substance (not the total energy) – Measured in units of • Degrees Fahrenheit (oF) • Degrees Celsius (oC) • Kelvin (K) • Heat is energy that _____. – flows from hot objects to cold objects – is absorbed/released by an object resulting in its change in temperature • Heat absorbed/released is measured by changes in temperature Substances Elements • Fundamental substances from which all things are constructed • Only one type of atom is present • Can not be broken down any further Substances Compounds • Substances made up of two or more elements in distinct ratios • Molecules: smallest characteristic part of a compound; composed of a distinct and unique arrangement of elements Temperature Scales • Fahrenheit Scale, °F – Water’s freezing point = 32°F, boiling point = 212°F • Celsius Scale, °C – Temperature unit larger than the Fahrenheit – Water’s freezing point = 0°C, boiling point = 100°C • Kelvin Scale, K – Temperature unit same size as Celsius – Water’s freezing point = 273 K, boiling point = 373 K Temperature of ice water and boiling water. • Heat Heat is the flow of energy due to a temperature difference – Heat flows from higher temperature to lower temperature • • • Heat is transferred due to “collisions” between atoms/molecules of different kinetic energy When produced by friction, heat is mechanical energy that is irretrievably removed from a system Processes involving Heat: 1. Exothermic = A process that releases heat energy. • Example: when a match is struck, it is an exothermic process because energy is produced as heat. 2. Endothermic = A process that absorbs energy. • Example: melting ice to form liquid water is an endothermic process. Heat (cont.) • The heat energy absorbed by an object is proportional to: – The mass of the object (m) – The change in temperature the object undergoes (DT) – Specific heat capacity (s) (a physical property unique to the substance) • To calculate heat (Q): Q = c . m . DT Specific Heat Capacity (c) • • The amount of heat energy (in J or Cal) required to increase the temperature of 1 gram of a substance by 1oC (or 1K) The Units of Specific Heat Capacity: 1. J/goC (SI) 2. cal/goC (metric & more useful in the lab) • Specific Heat Capacity is a unique physical property of different substances – Metals have low specific heat capacity – Non-metals have higher specific heat capacity – Water has an unusually large specific heat capacity c = Q/(mDT)