CHEMISTRY

1. CHEMISTRY

2. Elements • Pure substances that cannot be broken down chemically into simpler kinds of matter • More than 100 elements (92 naturally occurring)

3. 90% of the mass of an organism is composed of 4 elements (oxygen, carbon, hydrogen and nitrogen)

4. A compound is a pure substance made up of atoms of two or more elements • The proportion of atoms are always fixed • Chemical formula shows the kind and proportion of atoms of each element that occurs in a particular compound C6H12O6 + 6O2  6H2O +6CO2 + 36ATP subscripts Coefficient

5. Molecules are the simplest part of a compound that retains all of the properties of the substance and exists in a free state • Some molecules are large and complex

6. Chemical Formulas • Subscript after a symbol tell the number of atoms of each element • H20 has 2 atoms of hydrogen & 1 atom of oxygen • Coefficients before a formula tell the number of molecules • 3O2represents 3 molecules of oxygen or (3x2) or 6 atoms of oxygen

7. The tendency of elements to combine and form compounds depends on the number and arrangement of electrons in their outermost energy level • Atoms are most stable when their outer most energy level is full

8. Most atoms are not stable in their natural state (If they’re full, they won’t react) • Tend to react (combine) with other atoms in order to become more stable (undergo chemical reactions)

9. What are the 4 most common elements found in living things? • Hydrogen, sulfur, phosporous, calcium • Nitrogen, hydorgen, carbon, oxygen • Oxygen, sulfur, hydrogen, calcium • Carbon, hydrogen, phosphorous, nitrogen

10. Bonding with the four main Elements • H-needs 1 electron • O-needs 2 electrons • N- needs 3 electrons • C- needs 4 electron

11. C6H12O6 + 6O2  6H2O +6CO2 + 36ATP Reactants Products Chemical equations represent chemical reactions.  

12. Covalent Bonds • Formed when two atoms share one or more pairs of electrons

13. Ionic Bonds • Some atoms become stable by losing or gaining electrons • Atoms that lose electrons are called positive ions

14. Atoms that gain electrons are called negative ions • Because positive and negative electrical charges attract each other ionic bonds form

15. 2. Why do atoms form bonds? • To change from a gaseous state • To become more stable • To build larger molecules • To gather more electrons

16. Energy and Matter • Energy • The ability to do work or cause change • Can be converted to another form

17. Energy and Chemical Reactions • Living things undergo thousands of chemical reactions as part of the life process (Metabolism)

18. Energy Transfer • Much of the energy organisms need is provided by sugar (glucose) • Undergoes a series of chemical reactions in which energy is released (cell respiration)

19. 3. How many bonds can carbon atoms form? • 1 • 2 • 3 • 4

20. 4. Where are reactants found in a chemical equation? • On the left side • On the right side • Beneath the arrow • Above the arrow

21. Most chemical reactions require energy to begin • The amount of energy needed to start the reaction is called activation energy

22. Certain chemical substances (catalysts)reduce the amount of activation energy required • Biological catalysts are called enzymes

23. Enzymes are an important class of catalysts in living organisms • Mostly protein • Thousands of different kinds • Each specific for a different chemical reaction

24. Enzyme Structure • Enzymes work on substances called substrates • Substrates must fit into a place on an enzyme called the active site • Enzymes are reusable!

25. 5. The place on the enzyme into which the substrate fits is the __________ site. • Reaction • Metabolizing • Catalyzing • Active

26. Solutions

27. Solutions • A solution is a mixture in which 2 or more substances are uniformly distributed in another substance

28. 6. An enzyme is a(n) • Protein • Element • Substrate • atom

29. Solute is the substance dissolved in the solution • Particles may be ions, atoms, or molecules • Solvent is the substance in which the solute is dissolved • Water is the universal solvent

30. Solutions can be composed of varying proportions of a given solute in a given solvent --- vary in concentration(measurement of the amount of solute) • A saturated solution is one in which no more solute can be dissolved • Aqueous solution(water) are universally important to living things

31. Dissociation of water • 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) • OH-(hydroxide ion) • H+(hydronium ion)

32. Acids and Bases • One of the most important aspects of a living system is the degree of acidity or alkalinity

33. Acids • Number of hydronium ions in solutions is greater than the number of hydroxide ions

34. Bases • Number of hydroxide ions in solution is greater than the number of hydronium ions

35. pH Scale • concentrations of hydronium ions and hydroxide ions in a solution • ranges from 0 to 14 • Each pH is 10X stronger than next • e.g. ph 1 is 10 times stronger than ph 2

36. the lower the pH the stronger the acid • the higher the pH the stronger the base • pH 7.0 is neutral

37. Buffers • Control of pH is very important • Most enzymes function only within a very narrow pH • Control is accomplished with buffers made by the body • Buffers keep a neutral pH (pH 7)

38. Buffers neutralize small amounts of either an acid or base added to a solution • Complex buffering systems maintain the pH values of your body’s many fluids at normal and safe levels

39. 7. A liquid that has a pH of 3 is a(n) • Acid • Base • Neutral • Ion