Agenda Day 1. Classifying Matter. Objectives. Matter and Its Characteristics. Mass and Weight

Transcription

1 Agenda Day 1 Safety Video What is hemistry/intro Definitions KI + Pb(N3)2 lassifying Matter Elements, ompounds, Mixtures and Solutions Periodic Table lab safety bjectives Define Matter ompare and contrast mass and weight. Distinguish between elements and compounds ontrast mixtures and pure substances. lassify mixtures as homogenous or heterogeneous. List and describe several techniques used to separate mixtures. Matter and Its haracteristics Everything we see is matter. Matter: is anything that has mass and takes up space. Mass: is a measurement that reflects the amount of matter. Mass and Weight Don t get mass confused with weight. Weight: is a measure of matter, but also the affect of Earth s gravitational pull on that matter. It has two parts to the definition. Not the same everywhere on Earth. You weigh less on the top of Mt. Everest than at Key West, Florida. Defining matter Matter with the same properties throughout is homogeneous Matter that has parts with different properties is heterogeneous Appearance alone cannot always distinguish heterogeneous matter from homogeneous. 1

2 eterogeneous Matter eterogeneous matter is made of more than one kind of substance. It can be easily separated by physical means such as evaporation, magnetic separation, or picking pieces apart. omogeneous matter omogeneous matter may be pure substances or solutions Solutions are homogeneous mixtures Pure substances may be compounds or elements ompounds Elements Solutions Elements Elements are the new building blocks Found on the periodic table Made of atoms Pure substances All atoms of an element are identical ydrogen arbon-6 Nitrogen-7 xygen-8 arbon-6 Extreme Diversity Nitrogen-7 Fluorine-9 ompounds Made of 2 or more elements chemically joined Pure substances xygen-8 Neon-10 Made up of molecules All molecules of a compound are identical water molecules 2

3 ompounds are 2 or more different elements combined ompounds can have very different properties than the elements that make them up! ompounds = diversity. ydrogen arbon-6 ompounds are two or more elements that share electrons or have taken or given electrons away. Atoms and Molecules are always in motion ydrogen ydrogen ydrogen Si Si Si Si Si 3

4 9/6/2013 rganic compounds are compounds that usually come from organisms. They always have carbon plus a few other elements like hydrogen, oxygen, and nitrogen. Examples: Alcohol, Sugar, Fat, Protein Si Si Si Si Si The other common elements in order of abundance are the metals aluminum, iron, calcium, sodium, and potassium. ydrocarbons Plastic Diversity within Same Element Motor il Diesel Gasoline Diversity within Same Element Diversity within Same Element Amorphous arbon. Lampblack Used in black inks in paints, copiers, ink-jet printers. 4

5 bon Nanotubes Mixtures ombination of two or more pure substances in which each pure substance retains its individual chemical properties. Salt in water, Sand in water, Salt and Iron (Fe) Types of Mixtures eterogeneous Mixture: does not blend smoothly throughout and in which the individual substances remain distinct. etero- : ther; different. Sand and Water mixture Fresh Squeezed range Juice omogeneous Mixtures as a constant composition throughout; it always has a single phase. Salt water at the top of a beaker has the same concentration as salt water at the bottom of the beaker. Solution: homogeneous mixture that can be a gas, liquid, or solid or any combination of these. 5

6 Solutions Solutions are homogeneous mixtures They have different parts which are uniformly distributed and are too small to distinguish with the eye. Examples: salt water, pop Solid solutions are called alloys; they are a mixture of metals Examples: brass, sterling silver, 12K gold Solutions Gas-Gas: Air Gas-Liquid: Pop/Soda water Liquid-Gas: umid air Liquid-Liquid: Vinegar (water and acetic acid) Solid-Liquid: Kool-aid Solid-Solid: Steel (alloy of iron containing carbon) Solutions Rootbeer is a solution of water, sugar, carbon dioxide, and other flavorings Brass is a solution of opper and zinc Atoms of an Element Molecules of a ompound Diatomic Molecules of an Element Mixture of Elements & ompound Pure Substances and Mixtures lassification of Matter Pure Substances and Mixtures If matter is not uniform throughout, then it is a heterogeneous mixture. If matter is uniform throughout, it is homogeneous. If homogeneous matter can be separated by physical means, then the matter is a mixture. If homogeneous matter cannot be separated by physical means, then the matter is a pure substance. If a pure substance can be decomposed into something else, then the substance is a compound. 6

7 lassification of Matter Elements If a pure substance cannot be decomposed into something else, then the substance is an element. There are 114 elements known. Each element is given a unique chemical symbol (one or two letters). Elements are building blocks of matter. The earth s crust consists of 5 main elements. The human body consists mostly of 3 main elements. lassification of Matter ompounds Most elements interact to form compounds. Example, 2 The proportions of elements in compounds are the same irrespective of how the compound was formed. Law of onstant omposition (or Law of Definite Proportions): The composition of a pure compound is always the same. Formulas and Symbols Elements are represented by chemical symbols found on the periodic table. Examples:, N, S,, P, Au, g, Na ompounds are represented by chemical formulas Examples: N 2, N 3, Nal, Mixtures and solutions cannot be represented by a single formula or symbol Properties of Matter Physical vs. hemical Properties Physical properties can be measure without changing the basic identity of the substance (e.g., color, density, odor, melting point) hemical properties describe how substances react or change to form different substances (e.g., hydrogen burns in oxygen) Intensive physical properties do not depend on how much of the substance is present. Examples: density, temperature, and melting point. Extensive physical properties depend on the amount of substance present. Examples: mass, volume, pressure. Properties of Matter Separation of Mixtures Mixtures can be separated if their physical properties are different. Solids can be separated from liquids by means of filtration. The solid is collected in filter paper, and the solution, called the filtrate, passes through the filter paper and is collected in a flask. 7

8 Filtration Properties of Matter Separation of Mixtures omogeneous liquid mixtures can be separated by distillation. Distillation requires the different liquids to have different boiling points. In essence, each component of the mixture is boiled and collected. The lowest boiling fraction is collected first &w=314&sz=6&hl=en&start=2&tbnid=TjJ-tpPmQU5TM:&tbnh=122&tbnw=103&prev=/images%3Fq%3Dfiltration%26svnum%3D10% 26hl%3Den%26lr%3D%26rls %3DGWYG,GWYG: ,GWYG:en%26sa%3DN Distillation Separates homogeneous mixtures. Uses differences in boiling points. Properties of Matter Separation of Mixtures hromatography can be used to separate mixtures that have different abilities to adhere to solid surfaces. The greater the affinity the component has for the surface (paper) the slower it moves. The greater affinity the component has for the liquid, the faster it moves. hromatography can be used to separate the different colors of inks in a pen. hromatography Technique used to separate the components of a mixture on the basis of the tendency of each material to travel across the surface of another material. rystallization Separation technique that results in the formation of pure solid particles of a substance from a solution containing the dissolved substance

9 Energy The capacity to do some kind of work i.e. moving an object, forming a new compound, generating light More on Energy Kinetic energy is the energy of an object due to its motion Potential Energy is the energy associated with the relative position of bonds in a system. hemical energy is stored in chemical bonds. When broken, that energy can be released. More on Energy Energy is often transferred - scientists track the flow of energy between a system and its surroundings Energy can be transferred into different forms - chemical, mechanical, light, heat, electrical, sound, nuclear etc. Law of onservation of Matter Matter cannot be created or destroyed but can be changed from one form to another 9

10 Law of onservation of Energy Types of Energy Energy cannot be created or destroyed but can be changed from one form to another Type Kinetic or Potential Light - Electromagnetic Radition Electrical Electric current hemical hemical hanges eat Temperature transfer Mechanical Energy of doing work Nuclear Energy associated with mass of atoms Type Types of Energy Kinetic or Potential Solid Liquid Gas (Vapor) Plasma States of Matter Solid Definite shape Solid Molecules do not move Small space between molecules 10

11 Liquid Liquid Liquid takes the shape of its container Molecules move around slowly Moderate space between molecules Gas No definite shape Gas Molecules move fast Great space between molecules Plasma Plasma No definite shape Molecules move fast Great space between molecules 11

12 Some places where plasmas are found Flames Lightning Aurora (Northern Lights) The Sun is an example of a star in its plasma state Examples of Plasma ompare Space between Molecules Shape Solid Liquid Gas Plasma small moderate great great set container none none Speed of Molecules none slow fast fast Animation Video 12

13 Properties of Matter Physical and hemical hanges When a substance undergoes a physical change, its physical appearance changes. Ice melts: a solid is converted into a liquid. Physical changes do not result in a change of composition. When a substance changes its composition, it undergoes a chemical change: When pure hydrogen and pure oxygen react completely, they form pure water. In the flask containing water, there is no oxygen or hydrogen left over. Animation Properties of Matter Physical and hemical hanges hemical Reaction ne or more substances change into new substances. Reactant starting substance Product substance formed Indications of a hemical Reactions 1. Evolution of eat & Light 2. Production of a Gas 3. Formation of a Precipitate 4. olor hange June 2012 June

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