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Chemistry for Living Things

Chemistry for Living Things. Chapter 2. 2.1 Composition of Matter. Matter – anything that takes up space Mass – amount of matter in an object. Elements. Fundamental forms of matter Substances that are made up of 1 type of _______________ 92 occur naturally on Earth Others are man-made.

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Chemistry for Living Things

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  1. Chemistry for Living Things Chapter 2

  2. 2.1 Composition of Matter • Matter – anything that takes up space • Mass – amount of matter in an object

  3. Elements • Fundamental forms of matter • Substances that are made up of 1 type of _______________ • 92 occur naturally on Earth • Others are man-made atoms

  4. Most Common Elements in Living Organisms Carbon Hydrogen Oxygen Nitrogen

  5. What Are Atoms? • Smallest particles that keep properties of an element • Made up of 3 subatomic particles: • Protons (+) • Electrons (-) • Neutrons (no charge)

  6. - + - +

  7. electron proton neutron HYDROGEN HELIUM Hydrogen and Helium Atoms

  8. Atomic Number protons Atomic Number = Number of __________ • All atoms of an element have the same atomic number • Every element has a different atomic number • Atomic number of hydrogen = 1 • Atomic number of carbon = 6

  9. ATOMIC MASS Number of protons + Number of neutrons Isotopes vary in mass number

  10. atomic number 6 element symbol C atomic mass 12.011

  11. Isotopes • Atoms of an element with different numbers of _________________ • - they have a different mass number • eg. Hydrogen = protium (no neutron) • Hydrogen ISOTOPES: deuterium (1N) • tritium (2N) • Behave the same way in chemical reactions because they have the same # of electrons neutrons

  12. RADIOisotopes – emit (release) ENERGY

  13. <<LINK>> Isotopes of carbon 6 P 7 N 6 P 8 N 6 P 6 N 6 C 14 6 C 13 6 C 12 What is a difference between C12 and C14?

  14. Isotopes in Thyroid Scan • Measures health of thyroid by detecting radioactive iodine taken up by thyroid gland normal thyroid enlarged cancerous

  15. Radioactive urine for 24 hrs!

  16. What Determines Whether Atoms Will Interact? The number and arrangement of their electrons

  17. Electrons • Carry a negative charge • Repel one another • attracted to protons in the nucleus • Move in orbitals - volumes of space that surround the nucleus y Z X When all p orbitals are full

  18. Energy Levels – what is the max # electrons in each level? 2 8 8

  19. Show a Bohr Model for: Carbon (#6, mass12) Chlorine (#17, mass 35) Sodium (#11, mass 22)

  20. Lewis Dot Diagrams 9e • Represent the element by the chemical symbol and a “dot” for each valence electron. F 9 F 18 9 ___P ___N 9 electron Symbol for fluorine

  21. C Draw a Lewis Dot Diagram (aka Electron Dot or E Diagrams) for: Carbon Chlorine Sodium Cl Na

  22. Electron Vacancies • Unfilled shells make atoms likely to react • Hydrogen, carbon, oxygen, and nitrogen all have vacancies in their outer shells CARBON 6p+ , 6e- NITROGEN 7p+ , 7e- HYDROGEN 1p+ , 1e-

  23. Chemical Bonds, Molecules, & Compounds • Bond is union between electrons • Atoms bond to form molecules • Molecules may contain atoms of only one element - O2 (diatomic) (BrINClHOF) • Molecules of compounds contain more than one DIFFERENT element - H2O

  24. Chemical Formulas • Use symbols for elements and subscripts for the # of atoms • Formula for glucose is C6H12O6 • 6 carbons • 12 hydrogens • 6 oxygens

  25. Chemical Bookkeeping • Chemical equation shows required number of molecules to have the same number of atoms on both sides of the equation. Reactants --> Products • Equation for photosynthesis: CO2 + H2O ---> + C6H12O6 + H2O + O2 6CO2 + 12H2O ---> + C6H12O6 + 6H2O + 6O2

  26. Coefficients tell you the # of molecules • Subscripts tell you the # of each element in the chemical compound • YOU NEVER CHANGE SUBSCRIPTS to balance an equation, only coefficients

  27. Balancing EQUATIONS: 3 2 2 3 6 3 2

  28. Diatomic OR Compound Molecules Elements Atoms Subatomic particles

  29. Important Bonds Ionic Bonds - arrow Covalent Bonds – strongest, circle Polar covalent – H2O Hydrogen Bonds - weakest

  30. What is an ION? • A CHARGED atom or particle + -

  31. Ionic Bondingwhen you: If atom loses • __________ electrons, becomes positively charged ion • _____________ these electrons, becomes negatively charged ion • Charge difference attracts the two ions to each other If atom gains

  32. Formation of NaCl • Sodium atom (Na) • Outer shell has one electron • Chlorine atom (Cl) • Outer shell has seven electrons • Na transfers electron to Cl forming Na+and Cl- • Ions remain together as NaCl compound

  33. Formation of NaCl 7mm electron transfer SODIUM ATOM 11 p+ 11 e- CHLORINE ATOM 17 p+ 17 e- CHLORINE ION 17 p+ 18 e- SODIUM ION 11 p+ 10 e- Fig. 2.10a, p. 26

  34. Show a bond between magnesium(#12,mass24) and chlorine(#17,mass35): Note: MgCl2 means 1Mg and 2Cl atoms

  35. Covalent Bonding Atoms share a pair or pairs of electrons to fill outermost shell

  36. Methane CH4 3-D molecular model – shows actual shape/angle of the molecule

  37. Show a bond between carbon(#6,mass12) and hydrogens (#1,mass1) H H C H H

  38. Show a bond between silicon and oxygen atoms (hmm.. How many of each? What kind of bond will this be?)

  39. Show a bond between hydrogen and oxygen

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