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Chemistry in Biology: Elements, Compounds & Isotopes

Explore the significance of chemistry in biology with a focus on elements, compounds, and isotopes. Learn about chemical formulas, atomic structure, isotopic notation, and uses of radioisotopes in various applications. Discover the basics of chemical bonds and ions.

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Chemistry in Biology: Elements, Compounds & Isotopes

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  1. Honors Biology Chapter 2 Chemistry

  2. Are you wondering why we are learning chemistry in biology class? • All of our cells are made of chemical compounds. • All the activities of our bodies work on chemical reactions. • All of our body’s reactions use water. Such as neurotransmitters affecting neurons

  3. ELEMENTS • Substance that cannot be broken down to other substances by ordinary chemical means (heating, adding an acid…)

  4. COMPOUNDS • Substance of two or more different atoms chemically combined in a fixed ratio • EXAMPLES: CO2 • H2SO4 • H2O • CO • How is a compound written differently than an element? • More than one kind of element (more than one capital letter). • NOTE: H2 is not a compound – its an element • (Only one kind of element) Subscripts (tell how many atoms there are)

  5. Formula • Formula is the abbreviation for a compound. • CO2 H2SO4 H2O • Carbon dioxide sulfuric acid water • What rules seem to apply to writing a formula? • Capital letters for elements • Subscript number behind and just below the line of what element it represents

  6. Which are compounds? • Na N H2 NO2 H2O Why? • NO2 • H2O • 2 or more different elements chemically joined (2+ diff. capital letters)

  7. Can you figure out the difference between a mixture and a compound? • A mixtureis two or more elements (or compounds) NOT chemically joined. • A compound is two or more atoms chemically joined. • Do Worksheet: Elements, Compounds, Mixtures

  8. Atoms are made of protons, neutrons, electrons • Do you know what these particles are?

  9. Answers: • Do you know what these particles are? Protons Neutrons Electrons

  10. Basic Atomic Structure Youtube (1:57)

  11. What is the charge of each subatomic particle? • Proton Neutron Electron • + O _ • positive none negative

  12. What is the relative size? • Proton neutron electron • 1 amu 1 amu ~1/1836 amu • AMU = atomic mass unit = 1/12 CARBON ATOM • (standard)

  13. Neutral Atoms (no charge)(as seen on the periodic table) • 39 Mass Number p + n K Symbol • 19 Atomic Number p • (electrons = number of protons) • Neutral if negative charges = positive ) • n=mass no. – at.no.

  14. How can you tell the mass number and atomic number?

  15. Atomic Number In order Identify element by its number of protons Mass Number A decimal (average of masses of all isotopes of that element) When looking on the periodic table…

  16. Why is the mass number a decimal?Average of the Isotopes of Carbon • What is the mass number decimal? • 12.011 • What would you round it to? • 12

  17. What is the atomic number of? • Silicon fluorine sodium WHY? • 14 9 11 • Number in succession (not a decimal) • Number of protons

  18. What is the mass number of…? • Carbon nitrogen hydrogen • WHY? • 12 14 1 • Decimal number on periodic table • Not other number in succession • Number of p + n

  19. How do you find the number of…? • Protonselectrons neutrons Atomic atomic mass number numbernumber minus atomic no. (if neutral)

  20. How many? • Protons electrons neutrons • Carbon 6 6 6 • Chlorine • 17 17 18

  21. What is the atomic number?Mass Number? • Number of p? • Number of e-? • Number of n?

  22. Do Atomic Mass and Atomic Number WORKSHEET • Collaborate with your partner next to you, then we’ll see what’s right.

  23. ISOTOPES INTRO • Isotopes (Virtual School) (2:51) • Watch the video and list what facts you learned about isotopes. • No, not about the Albuquerque Isotopes

  24. Isotope • Atoms that differ in number of neutrons • Also differ in mass number(since it is p + n) • But all have the same number of protons

  25. Isotope Examples • What are isotopes? (7:56)

  26. Which is the most common isotope of Li? (check the periodic table)

  27. Why is the Mass Number a Decimal? • Finding the Average Atomic Mass (2:55) • Watch this and find out how…

  28. How do you write chemical notation for isotopes?

  29. 2.4 Radioactive Isotopes • An isotope that decays spontaneously to emit (give off) particles or energy until it is stable • Here a radioisotope is used to examine a thyroid gland • Radioactive Tracers in Medicine (3:57)

  30. Radioactive Decay Examples

  31. Uses of Radioisotopes • C-14 dating (can date living things up to 6,000 years old) Carbon Dating (2:00 mins) • Technetium 99 Radioisotope (2:58) • Nuclear Medicine: What to expect (2:46 mins) • Bozeman Biology Radioactive Dating (9 mins) • Carbon-14 Dating (2 mins) PET SCAN: detect tumors, weak spots in arteries Highlight parts of the body for diagnosis Thyroid tumor

  32. Uses of Radioisotopes • Iodine-131 PIB molecule to treat thyroid cancer detect Alzheimers PET scan

  33. Negative Effects of Nuclear Radiation • Chernobyl Nuclear Plant Accident

  34. Negative Effects of Radon • Radon, a radioactive gas, causes lung cancer • Found in regions containing uranium

  35. 2.5-2.7 Chemical Bonds

  36. Ion • Charged atom • Differs in number of electrons • 39 Same mass number K+ means lost one electron • 19 Same atomic number

  37. ION • Charged atom • Na+ (has lost one electron) • O-2 (has gained two electrons) • Shown with superscript +/- and number on upper right • (can omit number if a “1”) • What's and Ion? Youtube (6:52)

  38. Ions form by gaining or losing electrons

  39. O-2 has gained two electrons Na has lost an e- so it is Na+1

  40. Cation Anion Negative ion Cl- O-2 gained electrons • Positive ion • Na+ • Mg+2 • Lost electrons

  41. If one electron is… • Lost what charge will the ion have? • +1 11p+ 11 e- 11p+ 10e-

  42. Which are ions? • Cl O-2 Na+1 N2 Why? • O-2 Na+1 • Charged atoms (lost or gained electrons) • show charges as superscripts

  43. Valence Electrons • Outer shell electrons • Determines the bonding capacity of an atom

  44. How do electrons arrange themselves in an atom… • In the outer electron shells (energy levels)? • They are full with 2, 8, 8 • Fill inner shell first, then go to next shell out (Outermost shell has the greatest energy) Can you see any pattern how the e- arrange themselves?

  45. Get kinda complicated beyond 2,8,8…so that’s all we’ll do for now!

  46. Which electrons determine… • The chemical properties of the atom? • Outermost shell

  47. If one electron is gained… • What charge will the ion have? • -1

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