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Learn about the different types of matter - atoms, elements, molecules, and compounds. Discover the characteristics of pure substances and how they form the basis of all materials around us. Explore the properties and structures of different elements and compounds, and understand how mixtures vary from pure substances.
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TheClassification of MatterAtoms, Elements, Molecules and Compounds
PURE SUBSTANCE Something that can not be broken down into simpler matter using physical methods. There are two types of substances… Elements & Compounds.
ELEMENTS Are the simplest kind of pure substance. There are ~ 110 elements, each made of a different type of atom (periodic table).
Most elements can exist as a single atom (Fe, Cu):But some elements (mostly gases) usually exist as diatomic molecules (groups of 2 atoms). Diatomic Gases Hydrogen H2 Nitrogen N2 Oxygen O2 Fluorine F2 Chlorine Cl2 Bromine Br2 Iodine I2
Allotropes Different structural forms of the same element. • Oxygen has 3 allotropes: O Monatomic Oxygen (Single Oxygen Atom) O3 Ozone Molecule O2 Diatomic Oxygen Molecule
Allotropes of Carbon All are pure carbon. Each has a different structure. Diamond Graphite Fullerenes Carbon Nanotubes
COMPOUNDS Are pure substances that are composed of multiple types of elements (2 or more), chemically bonded to one another. Compounds can not be broken down by physical methods (they can be broken down by chemical reactions).
COMPOUNDS Have definite compositions, with element ratios indicated bysubscripts (H2O). We call this building blockthe “water molecule”.
COMPOUNDS The properties of compounds are very different from the properties of the elements that make them up!
MIXTURES A mixture is something that CAN be broken down into simpler materials using physical methods. There are 3 possible types of mixtures: • Element + Another Element • Compound + Another Compound • Element + Compound
MIXTURES There are 2 main types of mixtures: • Homogeneous- The parts are distributed evenly. Examples: Salt water; syrup; air; brass.
MIXTURES Homogeneous mixtures of liquids are called solutions. Homogeneous mixtures of metallic atoms are called alloys.
b) Heterogeneous- The parts are distributed unevenly. Examples: Spaghetti and Meatballs; Water + Oil mixture.
We learned that the properties of compounds are TOTALLY DIFFERENT from the properties of the elements that make them up. In contrast, the properties of mixtures ARE related to the properties of the substances that make the mixtures up. Properties of Saltwater
MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be chemically decomposed? Matter Flowchart MATTER yes no Can it be physically separated? Homogeneous Mixture Solutions + Alloys Heterogeneous Mixture Compound Element
Four different molecules: • Which are compounds?
Warmup 11/21/11 (R)Types of Particles: Atoms or Molecules or Both?Types of Matter: Elements or Compounds or Mixture?
Chemical Symbols Represent Elements Chemical Symbols are either one or two letters. If one letter, it is always capitalized. If two letters, the first is capitalized, the second is lower case. A chemical symbol implies one atom of that element.
Chemical Formula # of elements # of atoms total # of Carbon atoms Chemical Formulas show how many atoms of each element are in one molecule of an element or compound: O2 1 2 0 H2O 2 3 0 C3H8O 3 12 3 C6H12O4Cl 4 23 6
Nuts, Bolts, Washers Is it an element, compound, or mixture? What are the element and compound formulas?
Nuts, Bolts, Washers Is it an element, compound, or mixture? What are the element and compound formulas?
Nuts, Bolts, Washers Is it an element, compound, or mixture? What are the element and compound formulas?
WRITING FORMULAS When writing formulas, list the elements in this order: First…bolts. (Bo) Second…nuts. (Nu) Third…washers. (Wa) Example: BoNuWa2
Single Chemical Formula: • All pure substances can be represented by a H2O If it’s really a pure substance, you should only need to write ONE chemical formula to describe it’s composition.
How many atoms of each element are present in one molecule of: How many atoms of each element are present in one molecule of: How many atoms of each element are present in one molecule of: (NH4)2SO3 (NH4)2SO3 (NH4)2SO3 (NH4)2SO3 N……………. H…………… S……………. O…………… 2 8 1 3 2 8 1 3 2 8 1 3 2 8 1 3
Methods of Mixture Separation • Mechanical Separation (often by hand) takes advantage of physical properties such as color and shape. Example: Recycling Plastic, Paper, Metal
Methods of Mixture Separation 2) Magnetic Separation takes advantage of the physical property of magnetism. Example: Separating Metals in a Scrap Yard
Methods of Mixture Separation 3) Filtration takes advantage of the physical property of the state of matter. A screen lets the liquid particles through, but traps the solid particles. Example: Filtering Coffee, Spaghetti
A filter can also be used to separate solid particles ofdifferent sizes. (ex. a window screen, an air filter, a sand sieve)
Methods of Mixture Separation 4) Decanting: To pour off a liquid, leaving another liquid or solid behind. Takes advantage of differences in density. Example: To decant a liquid from a precipitate or water from rice.
Methods of Mixture Separation 5 ) Distillation: The separation of a mixture of liquids based on the physical property of boiling point. Example: the distillation of alcohol or oil
Methods of Mixture Separation 6) Evaporation: Vaporizing a liquid and leaving the dissolved solid(s) behind. Used to separate salt solutions. Example: Obtaining sea salt from sea water
Methods of Mixture Separation Density Separation: More dense components sink to the bottom and less dense components float.
Methods of Mixture Separation 7) Centrifuge: Circular motion helps denser components sink to the bottom faster. Examples: The separation of blood or DNA from blood
Methods of Mixture Separation • Paper chromatography: Uses the property of molecular attraction to separate a mixture. Different molecules have different attractions for the paper (the stationary phase) vs. the solvent (the mobile phase) Example: the separation of plant pigments and dyes
Methods of Mixture Separation Fractional Crystallization: Dissolved substances crystallize out of a solution once their solubility limit is reached as the solution cools. Examples: Growing Rock Candy or the Crystallization of a Magma Chamber