Chemistry Edited

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Chemistry Edited

  1. 1. CHEMISTRY
  2. 2. Composition of Matter <ul><li>Matter - Everything in universe is composed of matter </li></ul><ul><ul><li>Matter is anything that occupies space or has mass </li></ul></ul><ul><ul><ul><li>Mass – quantity of matter an object has </li></ul></ul></ul><ul><ul><ul><li>Weight – pull of gravity on an object </li></ul></ul></ul>
  3. 3. Elements <ul><li>Pure substances that cannot be broken down chemically into simpler kinds of matter </li></ul><ul><li>More than 100 elements (92 naturally occurring) </li></ul>
  4. 4. <ul><li>90% of the mass of an organism is composed of 4 elements (oxygen, carbon, hydrogen and nitrogen) </li></ul><ul><li>Each element unique chemical symbol </li></ul><ul><ul><li>Consists of 1-2 letters </li></ul></ul><ul><ul><li>First letter is always capitalized </li></ul></ul>
  5. 5. Atoms <ul><li>The simplest particle of an element that retains all the properties of that element </li></ul><ul><li>Properties of atoms determine the structure and properties of the matter they compose </li></ul><ul><li>Our understanding of the structure of atoms based on scientific models not observation </li></ul>
  6. 6. The Nucleus <ul><li>Central core </li></ul><ul><li>Consists of positive charged protons and neutral neutrons </li></ul><ul><li>Positively charged </li></ul><ul><li>Contains most of the mass of the atom </li></ul>
  7. 7. The Protons <ul><li>All atoms of a given element have the same number of protons </li></ul><ul><li>Number of protons called the atomic number </li></ul><ul><li>Number of protons balanced by an equal number of negatively charged electrons </li></ul>
  8. 8. The Neutrons <ul><li>The number varies slightly among atoms of the same element </li></ul>
  9. 9. The Electrons <ul><li>Negatively charged high energy particles with little mass </li></ul><ul><li>Travel at very high speeds at various distances (energy levels) from the nucleus </li></ul>
  10. 10. <ul><ul><li>Electrons in the same energy level are approximately the same distance from the nucleus </li></ul></ul><ul><ul><li>Outer energy levels have more energy than inner levels </li></ul></ul><ul><ul><li>Each level holds only a certain number of electrons </li></ul></ul>
  11. 11. Compounds <ul><li>Most elements do not exist by themselves </li></ul><ul><li>Readily combine with other elements in a predictable fashion </li></ul>
  12. 12. <ul><li>A compound is a pure substance made up of atoms of two or more elements </li></ul><ul><ul><li>The proportion of atoms are always fixed </li></ul></ul><ul><li>Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound </li></ul>
  13. 13. <ul><li>The physical and chemical properties of a compound differ from the physical and chemical properties of the individual elements that compose it </li></ul>
  14. 14. <ul><li>The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their atoms </li></ul><ul><li>Atoms are most stable when their outer most energy level is filled </li></ul>
  15. 15. <ul><li>Most atoms are not stable in their natural state </li></ul><ul><li>Tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions) </li></ul><ul><li>In chemical reactions bonds are broken; atoms rearranged and new chemical bonds are formed </li></ul>
  16. 16. Covalent Bonds <ul><li>Formed when two atoms share one or more pairs of electrons </li></ul>
  17. 17. <ul><li>Molecules are the simplest part of a substance that retains all of the properties of the substance and exists in a free state </li></ul><ul><li>Some molecules are large and complex </li></ul>
  18. 18. Ionic Bonds <ul><li>Some atoms become stable by losing or gaining electrons </li></ul><ul><li>Atoms that lose electrons are called positive ions </li></ul>
  19. 19. <ul><li>Atoms that gain electrons are called negative ions </li></ul><ul><li>Because positive and negative electrical charges attract each other ionic bonds form </li></ul>
  20. 20. States of Matter <ul><li>Atoms are in constant motion </li></ul><ul><li>The rate at which atoms or molecules in a substance move determines its state </li></ul>
  21. 21. <ul><ul><li>Solid </li></ul></ul><ul><ul><ul><li>Molecules tightly linked together in a definite shape </li></ul></ul></ul><ul><ul><ul><li>Vibrate in place </li></ul></ul></ul><ul><ul><ul><li>Fixed volume and shape </li></ul></ul></ul>
  22. 22. <ul><ul><li>Liquids </li></ul></ul><ul><ul><ul><li>Molecules not as tightly linked as a solid </li></ul></ul></ul><ul><ul><ul><li>Maintain fixed volume </li></ul></ul></ul><ul><ul><ul><li>Able to flow and conform to shape of container </li></ul></ul></ul>
  23. 23. <ul><ul><li>Gas </li></ul></ul><ul><ul><ul><li>Molecules have little or no attraction to each other </li></ul></ul></ul><ul><ul><ul><li>Fill the volume of the occupied container </li></ul></ul></ul><ul><ul><ul><li>Move most rapidly </li></ul></ul></ul><ul><li>To cause a substance to change state, thermal energy must be added to or removed from a substance </li></ul>
  24. 24. Solutions <ul><li>A solution is a mixture in which 2 or more substances are uniformly distributed in another substance </li></ul>
  25. 25. <ul><li>Solute is the substance dissolved in the solution </li></ul><ul><ul><li>Particles may be ions, atoms, or molecules </li></ul></ul><ul><li>Solvent is the substance in which the solute is dissolved </li></ul>
  26. 26. <ul><li>Solutions can be composed of varying proportions of a given solute in a given solvent --- vary in concentration (measurement of the amount of solute) </li></ul><ul><li>A saturated solution is one in which no more solute can be dissolved </li></ul><ul><li>Aqueous solution (water) are universally important to living things </li></ul>
  27. 27. Acids and Bases <ul><li>One of the most important aspects of a living system is the degree of acidity or alkalinity </li></ul>
  28. 28. <ul><li>Dissociation of water </li></ul><ul><ul><li>Breaking apart of the water molecule into two ions of opposite charge (due to strong attraction of oxygen atom of one molecule for H atom of another water molecule) </li></ul></ul><ul><ul><li>H 2 O  H + (hydrogen ion) + OH - (hydroxide ion) </li></ul></ul>
  29. 29. Acids <ul><li>Number of hydronium ions in solutions is greater than the number of hydroxide ions </li></ul><ul><ul><ul><li>HCl  H + + Cl - </li></ul></ul></ul>
  30. 30. Bases <ul><li>Number of hydroxide ions in solution is greater than the number of hydronium ions </li></ul><ul><ul><ul><li>NaOH  Na + + OH - </li></ul></ul></ul>
  31. 31. pH Scale <ul><li>logarithmic scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution </li></ul><ul><li>ranges from 0 to 14 </li></ul>
  32. 32. <ul><li>the lower the pH the stronger the acid </li></ul><ul><li>the higher the pH the stronger the base </li></ul><ul><li>pH 7.0 is neutral </li></ul>
  33. 33. Buffers <ul><li>Control of pH is very important </li></ul><ul><li>Most enzymes function only within a very narrow pH </li></ul><ul><li>Control is accomplished with buffers </li></ul>
  34. 34. <ul><li>Buffers neutralize small amounts of either an acid or base added to a solution </li></ul><ul><li>Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels </li></ul>

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