Classifying Matter


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  • chalk = calcium carbonite (CaCH3) ammonia = NH3
  • Jell-O is a colloid: a heterogeneous mixture with particles larger than those in a solution, but not large enough to settle out. Milk, paint, and mayo are, too (and aerosols).
  • brass = copper + zinc vinegar = acetic acid and water.
  • CuSO4 = copper sulfate
  • Quick review on rounding to a whole number: Jeanne's method: circle the one's place number draw arrow to number on the right if it's 5 or above, the circled number is raised one digit if it's 4 or below, the circled number STAYS THE SAME In the example here, round the mass to 96. Neutrons = 96-42 = 54 Isotopes: One of two or more atoms that have the same atomic number (the same number of protons) but a different number of neutrons. Carbon 12, the most common form of carbon, has six  protons and six neutrons, whereas carbon 14 has six protons and eight neutrons. Isotopes of a given element typically behave alike chemically. With the exception of hydrogen, elements found on Earth generally have the same number of protons and neutrons; heavier and lighter isotopes (with more or fewer neutrons) are often unstable and undergo radioactive decay .
  • Don't go into too much detail at this point about valence electrons and reactivity.
  • Classifying Matter

    1. 1. Classifying Matter Basic Chemistry Heartlife Physical Science
    2. 2. Matter - What is it? <ul><li>Matter is anything that: </li></ul><ul><ul><li>has mass </li></ul></ul><ul><ul><li>takes up space </li></ul></ul><ul><li>All matter is made up of atoms </li></ul><ul><ul><li>more than 100 different kinds </li></ul></ul><ul><ul><li>two or more combined (joined) atoms make a molecule </li></ul></ul><ul><li>Elements are substances made from only one type of atom </li></ul><ul><ul><li>i.e. gold, carbon, helium, neon, sulfur </li></ul></ul><ul><li>Compounds are substances made from two or more different combined elements </li></ul><ul><ul><li>ratios remain constant (there will always be twice as much Helium as Oxygen in water) </li></ul></ul><ul><ul><li>i.e. carbon dioxide, sodium chloride (salt), iron oxide (rust), ammonia, water, chalk </li></ul></ul>Oxygen Molecule O 2 Water Molecule H 2 O Oxygen atom O
    3. 3. Mixtures <ul><li>A mixture is made of different substances (elements or compounds) that can be physically separated </li></ul><ul><ul><li>contain different ratios of substances </li></ul></ul><ul><ul><li>examples: </li></ul></ul><ul><ul><ul><li>some fruit salad might have more grapes than bananas </li></ul></ul></ul><ul><ul><ul><li>some granite has more feldspar in with the mica than others </li></ul></ul></ul>Granite <ul><ul><li>How can substances be separated out of mixtures? </li></ul></ul><ul><ul><ul><li>by hand or with tweezers </li></ul></ul></ul><ul><ul><ul><li>evaporation or distillation </li></ul></ul></ul><ul><ul><ul><li>filtering </li></ul></ul></ul><ul><ul><ul><li>settling in layers (centrifuge) </li></ul></ul></ul><ul><ul><ul><li>magnets </li></ul></ul></ul>
    4. 4. Mixtures - Fruit Salad vs. Whipped Cream <ul><li>Heterogeneous mixtures are unevenly mixed </li></ul><ul><ul><li>different substances clump together </li></ul></ul><ul><ul><li>easily identified as separate substances </li></ul></ul><ul><ul><li>examples: granite, soil, sand, salad dressing, OJ </li></ul></ul><ul><li>Homogeneous mixtures are evenly mixed </li></ul><ul><ul><li>particles are uniformly dispersed (spread out) </li></ul></ul><ul><ul><li>even with a microscope, different substances can't be identified </li></ul></ul><ul><ul><li>examples: air, brass, antifreeze, whipped cream, apple juice </li></ul></ul>
    5. 5. Solutions <ul><li>A solution is a homogeneous mixture in which one or more solutes (particles of a substance) are distributed uniformly throughout another substance (the solvent ) </li></ul><ul><ul><li>solutes & solvents can be solids, liquids or gases </li></ul></ul><ul><ul><li>the solvent is the substance in greatest quantity in the solution </li></ul></ul><ul><li>Examples: </li></ul><ul><ul><li>air is a solution of several different gases (O 2 , CO 2 , Ar) equally distributed in Nitrogen gas </li></ul></ul><ul><ul><li>alloys (such as sterling silver or dental fillings) are solid solutions </li></ul></ul><ul><ul><li>carbonated drinks are sugar, flavorings and carbon dioxide gas solutes uniformly dispersed in water </li></ul></ul>
    6. 6. Summing up the &quot;Matter&quot;
    7. 7. Properties of Matter <ul><li>Physical properties : observed characteristics that describe a substance </li></ul><ul><ul><li>State of matter (solid, liquid, gas, plasma, B-E condensate) </li></ul></ul><ul><ul><li>Melting and boiling point </li></ul></ul><ul><ul><li>Size, density, mass, volume </li></ul></ul><ul><ul><li>Temperature, color , texture, etc. </li></ul></ul><ul><li>Chemical properties : characteristics that describe how a substance's composition can change (undergo a chemical reaction) </li></ul><ul><ul><li>Flammability </li></ul></ul><ul><ul><li>Susceptibility to rust (oxidation state) </li></ul></ul><ul><ul><li>Resistance to decomposition </li></ul></ul><ul><ul><li>Reactivity to other substances </li></ul></ul><ul><ul><li>Toxicity </li></ul></ul>
    8. 8. Chemical Formulas <ul><li>Each element has a symbol </li></ul><ul><ul><li>O for Oxygen, C for Carbon, Cl for Chlorine, etc. </li></ul></ul><ul><ul><li>Periodic Table of the Elements lists these symbols </li></ul></ul><ul><li>A compound's chemical composition can be written out as a formula showing the ratio of different elements </li></ul><ul><li>The subscript # refers to the symbol before it </li></ul><ul><li>Example: Water </li></ul><ul><ul><li>For every one atom of Oxygen, there are two Hydrogen atoms </li></ul></ul>H 2 O Water NaCl Sodium Chloride CH 4 Methane H 2 O 2 Hydrogen peroxide CO Carbon monoxide CO 2 Carbon dioxide NH 3 Ammonia Chemical Formula Compound Common Compounds
    9. 9. Physical vs. Chemical Changes <ul><li>When matter undergoes a physical change: </li></ul><ul><ul><li>it alters the state, shape or appearance </li></ul></ul><ul><ul><li>it retains it's chemical composition </li></ul></ul><ul><ul><li>the original matter can be recovered </li></ul></ul><ul><ul><ul><li>i.e. wood is still wood after being cut or shredded into sawdust, but its size and shape may change </li></ul></ul></ul><ul><li>When matter undergoes a chemical change: </li></ul><ul><ul><li>it changes into a totally different type of matter </li></ul></ul><ul><ul><li>it's chemical composition changes (atoms and molecules are broken apart or combined differently to form new substances) </li></ul></ul><ul><ul><li>the original matter cannot be recovered </li></ul></ul><ul><ul><ul><li>i.e. wood that is burned changes into charcoal and ashes </li></ul></ul></ul>
    10. 10. Examples of Physical & Chemical Changes You fry an egg. Your body digests food.  You take an antacid to settle your stomach.  A match is lit. Food scraps turn into compost.   Hydrogen peroxide bubbles in a cut.  Rubbing alcohol evaporates on your hand. Gasoline is ignited. A juice box in the freezer freezes. Rust forms on a nail left outside. Water evaporates from the ocean's surface. Bread becomes toast. Butter melts on warm toast. Jewelry tarnishes. Clay is molded into a new shape. Milk goes sour. Aluminum foil is cut in half. Chemical Changes Physical Changes
    11. 11. <ul><li>Atoms are the smallest particles comprising matter </li></ul><ul><ul><li>every atom is made up of </li></ul></ul><ul><ul><ul><li>at least one positively charged proton </li></ul></ul></ul><ul><ul><ul><li>one or more neutrons (except hydrogen) </li></ul></ul></ul><ul><ul><ul><li>one or more shells of negatively charged electrons </li></ul></ul></ul>What is matter made of? in a dense, central nucleus Atoms are mostly empty space!
    12. 12. Nuclear Particles <ul><li>Protons </li></ul><ul><ul><li>located in the nucleus of an atom </li></ul></ul><ul><ul><li>each proton has a positive (+1) charge </li></ul></ul><ul><ul><li>&quot;heavy&quot; (has a significant mass) </li></ul></ul><ul><li>The number of protons in an atom determines the type of element </li></ul><ul><ul><li>1 proton = Hydrogen </li></ul></ul><ul><ul><li>3 protons = Lithium </li></ul></ul><ul><ul><li>8 protons = Oxygen </li></ul></ul><ul><li># of protons can be found on the periodic chart as the atomic number </li></ul>p +
    13. 13. Nuclear Particles <ul><li>Neutrons </li></ul><ul><ul><li>located in the nucleus </li></ul></ul><ul><ul><li>neutrons have no charge (0) </li></ul></ul><ul><ul><li>&quot;heavy&quot; (has a significant mass) </li></ul></ul>n 0 <ul><li>The number of neutrons varies within elements </li></ul><ul><ul><li># of neutrons can be determined using the periodic chart </li></ul></ul><ul><ul><ul><li>atomic mass = average weight of protons & neutrons combined (taking into account all its isotopes ) </li></ul></ul></ul><ul><ul><ul><li>neutrons = atomic mass (rounded to nearest whole #) minus the atomic number </li></ul></ul></ul>
    14. 14. Orbiting Particles <ul><li>Electrons </li></ul><ul><ul><li>travel around the nucleus in a circular pattern </li></ul></ul><ul><ul><ul><li>impossible to know the exact position or velocity </li></ul></ul></ul><ul><ul><li>each electron has a negative (-1) charge </li></ul></ul><ul><ul><li>&quot;light&quot; (contributes virtually nothing to the mass of an atom) </li></ul></ul>e - <ul><li>The number of electrons usually equals the number of protons (atomic #) </li></ul><ul><ul><li>When the # of negative charges (electrons) equals # of positive charges (protons), they balance out. </li></ul></ul><ul><ul><li>Sometimes there are extra or missing electrons. </li></ul></ul><ul><ul><ul><li>This results in an ion (net (-) or (+) charge on the atom) </li></ul></ul></ul>
    15. 15. Electrons in Motion <ul><li>Electron Shells (also called energy levels or orbitals) show where electrons are likely to spend most of their time. </li></ul><ul><ul><li>Each shell holds a different maximum number of electrons. </li></ul></ul><ul><ul><li>A better description of where electrons hang out is the term &quot;electron cloud&quot; </li></ul></ul><ul><li>Electrons are happiest </li></ul><ul><ul><li>in pairs </li></ul></ul><ul><ul><li>with full shells </li></ul></ul><ul><li>Lone electrons are unstable and highly reactive! </li></ul>