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CHEMISTRY -

CHEMISTRY - . the study of the structure and composition of matter , the physical and chemical changes it undergoes and the energy that is exchanged. ?. structure is the order in which the atoms are actually hooked together and how they bond

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CHEMISTRY -

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  1. CHEMISTRY - the study of the structure and composition of matter, the physical and chemical changes it undergoes and the energythat is exchanged.

  2. ? • structure is the order in which the atoms are actually hooked together and how they bond • composition is what kinds of elements actually make-up something • Matter is the physical "stuff" of the universe. It is defined as anything which has mass and occupies space. • Law of Conservation of Matter: Matter can neither be created nor destroyed only changed by physical or chemical means.

  3. Homogeneous Matter homogeneousmeans that it is one phase throughout; completely uniform ex: water ELEMENT - matter composed of only one type of atom; the simplest form of matter; cannot be changed to another element except by a NUCLEAR reaction • 112 have been discovered but only 109 have been named and their names accepted; only 88 elements are naturally occurring; all others are man made • the symbol for an element is 1 capital letter OR 1 capital letter and 1 lower-case letter. • Some elements are named by their English names the element Carbon is symbolized by its English name: Carbon: C • Some are named by their Latin names: • Ex: The element Sodium is symbolized by its Latin name: Natrium: Na

  4. Homogeneous matter COMPOUNDS are substances composed of more than one atom chemically joined together • compounds can be changed to other compounds and separated by chemical reactions only cannot be physically separated. • compounds do not have the same properties of the elements which make them up. EX: H2O • the chemical formula for a compound will have more than 1 capital letter in it because it contains more than one element, Ex: C12H22O22 • the proportions of elements in a compound do not change or you have changed the compound. For example H2O vs H2O2

  5. Homogeneous Solutions • SOLUTIONS are a uniform mix of two or more substances which are NOT chemicallybonded and therefore, unlike compounds, each component retains its original identity and properties, you cannot see the particles of these two substances and thus a solution allows the transmittance of light. A solution has TWO parts-- • SOLUTE is the component which whose phase is changed. ONLY if both components are the same phase, the solute is the one in the LESSER quantity For example: Sugar and water • SOLVENT is the component which remains unchanged. ONLY if both components are the same phase, the solvent is the one in the GREATER quantity. When two liquids are mixed, we describe their interaction as: • MISCIBLE: If they dissolve in each other completely and mix uniformly in any proportions An example of miscible liquids is vinegar and water. • IMMISCIBLE: If the two liquids do not dissolve in each other and form two distinct layers, they are said to be Examples of immiscible liquids are oil and water. • Alloy: When two metals are melted together, like gold and silver to make jewelry

  6. Gold Alloys • Percentage by WeightThe following table shows typical "recipes" for different common gold alloys.

  7. Example practice • Example 2-1: • Aluminum chloride is a white crystal. Alcohol is a clear liquid. When these are mixed, a clear liquid solution results. What is the solvent? • If there is 91% gold , 7 % silver and 3% copper in 22 kt gold, an alloy. What is the solvent? What are the solutes?

  8. Heterogeneous Matter:HETEROGENEOUS SUBSTANCES ARE ALWAYS MIXTURES! Theyare not uniform in composition. There is more than one phase present • Dry Heterogeneous Mixtures: made of dry particles of different types can be elements and/or compounds. If a solution has particles in it, it is not technically called a solution anymore. There are two ways we name these types of heterogeneous mixtures: • Colloid: a mixture who’s particles are evenly distributed and bigger than the particles in a solution but smaller than the particles in a suspension • Suspension: a mixture who’s particles are so large that they settle out unless constantly agitated.

  9. Practice: TO CLASSIFY MATTER, YOU MUST ALWAYS USE TWO WORDS--HOMOGENEOUS ELEMENT, HOMOGENEOUS COMPOUND, HOMOGENEOUS SOLUTION OR HETEROGENEOUS MIXTURE. • Vinegar (acetic acid diluted in water) • birdseed • cooking oil • mouthwash • ketchup • water • silver • mayonnaise

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