2. Chapter 6 SOL.3 Page 145 Chemistry Of Life

3. Chemistry Objectives Students will be able to distinguish between ionic and covalent bonds. Students will be able to analyze the properties of water. Students will be able to differentiate between an acid and a base.

4. Why chemistry?  Because it will help you learn about biology since organisms including humans are chemical machines

5. Matter  Consists of ATOMS!  An atom is the smallest unit of matter  They are so small that their exact size is difficult to determine

6. Matter Name of ParticleLocationCharge Nucleus + 0 Surrounds the nucleus in energy levels -

7. Matter  Atoms typically have one electron for each proton so they have no charge

8. Matter  Electrons constantly move around an atom’s nucleus in energy levels.

9. Elements  An element is made up of only one type of atom  Considered a pure substance  Ex: In pure gold, there are only gold atoms

10. Elements  Groups vs periods   Each element has a symbol  First letter is capitalized  Second letter is lower case

11. Common Elements The most common elements in Biology: C Fe H O P K I N S Ca Mg Na Cl

12. Isotope Atoms of an element that contain different number of neutrons which give it a different mass Where is this used? Radioactive dating

13. Compound A substance made of the joined atoms of 2 or more different elements Example: NaCl = Table salt Water = H 2 O Carbon dioxide = CO 2 Methane = CH 4 Hydrochloric acid = HCl

14. 3 Types of Bonds  Covalent Bonds  Ionic Bonds  Hydrogen Bonds

15. Covalent Bonds Electrons are shared Electrons want to fill each energy level (They like even numbers ) Molecule = compound held together with cov. Bonds

16. Bonding Electrons are shared Electrons want to fill each energy level! (They like even numbers ) Because the number of protons is equal to the number of electrons the molecule has… No Charge! Stable! Examples: CO 2 and H 2 O

18. Ionic Bonds Electrons are gained or stolen! ION: An atom that has gained or lost an electron Ions have an electrical charge because they contain an unequal number of p + and e - An atom that has LOST an e - : + charge An atom that has GAINED an e - : - charge Why?

19. Ionic Bond Ions of opposite charges may interact to form an Ionic bond. Opposites attract… like magnets Which is a +ion and which is –ion?

20. Since Salt (NaCl) is formed from an ionic bond and water is said to be polar because of its charges; This enables salt to be easily dissolved into water because of the charges of all the elements Ionic Bond

21.  Opposites attract and the salt gets dissolved!!!

22. Hydrogen Bonds A weak chemical attraction between polar molecules Electrons in a water molecule are shared by oxygen and hydrogen atoms Therefore, the molecule has different charges and polar ends These ends are also known as poles This type of bond is weaker + + -

23. Head/Arms Demo

24. Chemical Reaction  Chemical reactions allow living things to grow, develop, reproduce and adapt  Process where atoms or groups of atoms in substances are reorganized into different substances  C + O 2 = CO 2

25. Chemical Reaction Chemical change – new substances are made New chemical makeup Physical change – the appearance changes, but it remains the same substance No new chemical makeup 

26. Chemical Reaction Reactants  products  means “yields”

27. Chemical Reaction The key to starting any chemical rxn is ENERGY Activation Energy The minimum amount of energy needed to start a chemical reaction

28. Chemical Reaction Endothermic Rxns The energy of the products is higher than the energy of the reactants Energy was absorbed

29. Chemical Reaction Exothermic Rxns The products have a lower amount of energy than the reactants Energy is released

30. Enzymes (Catalysts) All living things are chemical factories driven by chemical reactions. Catalyst – lowers the activation energy for chemical reactions. Does not increase product Does not get used up

31. Enzymes (Catalysts) Biological catalysts that speed up the rate of biological processes Proteins Essential for life Name describes what it does Amylase Lactase

32. Enzymes (Catalysts) Substrate: reactants that bond to substrates Active Site: the location where a substrate binds to the enzyme Heat and pH affect enzymes 

33. Enzymes (Catalysts)

34. WATER PROPERTIES

35. Water Water helps us maintain homeostasis All of your cells are 70% water One of the most important molecules for life

36. Water … Makes hydrogen bonds with other water molecules Weak attraction between water molecules Electrons are unevenly shared Oxygen = - (negative pole) Hydrogen = + (positive pole) Polar molecules: molecules that have an uneven distribution of molecules ONLY polar substances dissolve in water!!!!

37. Polarity Non polar molecules do not dissolve well in water Oil! Gasoline! When non-polar substances are placed in water the water molecules are more attracted to each other than the non-polar molecules

38. Water … Water molecules are like magnets to other water molecules They are attracted to each other

39. Cohesion The attraction between substances of the same kind. This creates surface tension Forms droplets This prevents the surface of water from stretching or breaking easily and things getting wet

40. Surface Tension

41. Adhesion Water forms h-bonds with materials on other surfaces Creates capillary action Water is pulled up a straw or a stem

42. Capillary Action

43. Mixtures Mixture: combination of 2 or more substances Homogenous mixtures: even composition throughout the solution Solute: substance being dissolved (Kool-Aid powder) Solvent: substance doing the dissolving (water)

44. Mixtures Heterogeneous mixture: you can still see individual components Suspension: contains solid particles too big to dissolve Colloid: big particles, but they do not settle out

45. Acids & Bases If water is broken down it forms hydrogen ions (H + ) and hydroxide ions (OH - ) H 2 0  H + + OH -

46. Acids form H + ions when dissolved in water Sour tasting Feels tingling/burning Can be very corrosive at high levels Turns blue litmus paper red Ranges from 0-6.9 On the left side Examples include:

47. Bases Compound that form hydroxide ions when dissolved in water AKA alkaline Taste bitter Feels slippery Turns red litmus paper blue Ranges from 7.1 – 14 On the right side Examples include:

48. pH scale measuring the concentratin of H+ ions in a solution

49. pH Scale (Power of Hydrogen Scale) Ranges from 0 to 14 Each number is 10 times stronger/weaker than the one next to it For example: 1 is 10x stronger than 2 or 100x stronger than 3 Neutral is at 7 Buffer: Keep pH within a certain range Antacids

50. Let’s Draw It!!

51. Litmus Paper Test http://www.bgfl.org/bgfl/custom/resour ces_ftp/client_ftp/ks3/science/acids/ Explains litmus paper Use this with your pH Lab Report to help you…. Be sure to print your results