Atoms and Bonding

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Atoms and Bonding

  1. 1. σ- O H H σ+ σ+Atoms and Bonding Intro to Chemistry MrT staylor@canacad.ac.jp
  2. 2. It has electrons and protons in the nucleus and neutrons outside. The electrons are the heaviest part, which is why they’re outside. The nucleus is overall positive and the electrons are negatively charged.Clipart people from: http://www.clker.com/search/krug/1
  3. 3. Atoms and Bonding Unit Questions: “How can we know what we cannot see?” Enduring Understandings: • Patterns and structures lead to predictability Areas of interaction: Human Ingenuity The Periodic Table is an amazing feat of the scientific method and reason.Criterion Assessment TasksB: Communication Sports Drinks LabC: Knowledge & Understanding Mystery elements bonding task (test conditions) Quia Review Quizzes: • 2.1 Atoms, ions, isotopes • 2.2 Periodic Table and structure • 2.3 Ionic and Covalent Bonding • 2.4 Intermolecular forces
  4. 4. Atoms and BondingAssessment Statements • Define valence electrons and outline the duet• Describe the components of the atom and octet rules. (protons, neutrons, electrons), in terms of • Draw Lewis dot structures for the valence size and charge. electrons of elements on the periodic table.• Outline the structure of the atom. • Deduce whether two elements will form an• Distinguish between atomic number, mass number and atomic mass. ionic or covalent compounds from their position on the periodic table• Deduce the atomic number and mass • Explain the formation of ionic bonds. number of an element from its position on • Describe the properties of ionic compounds. the periodic table. • Describe metallic bonds and their properties.• Outline the formation of isotopes, using • Define molecule. examples. • Explain the formation of covalent bonds,• Distinguish between atoms and ions. using Lewis dot structures.• Explain how cations and anions are formed, • Describe the properties of covalently bonded with examples. molecules.• Outline the organisation of the periodic • Outline how covalent bonding leads to polar table in terms of groups, periods and bonds and molecules. families. • Explain hydrogen bonding in water as an• Describe the trend in atomic structure through the periodic table. example of dipole-dipole attractions. • Describe Van der Waals Forces.
  5. 5. Build an AtomRun the simulation and build the following:1. a hydrogen atom.2. the hydrogen cation.3. helium.4. a stable isotope of helium.5. an unstable istotope of helium.Answer the following:1. Which subatomic particle determines the element’s atomic number? Build an Atom, from PhET. Click Run Now. http://phet.colorado.edu/en/simulation/build-an-atom2. Which two subatomic particles determine the element’s mass number? If you’re done:3. How is ionic charge (net charge) What level can you reach on the game? determined and what makes an ion?4. What is an isotope and how is it made?Then test yourself (and research further):http://www.quia.com/quiz/3320413.html(firstnamelastname230, milk)
  6. 6. - Atom Nucleus and electron cloud Electron (e-) (mass = negligible, charge: -1) Neutron (n0) + (mass = 1amu*, charge: 0) Nucleus contains nucleons + Proton (p+) (mass = 1amu, charge: +1) Mass number is the Atomic number is Atomic mass is the total number of the number of mean mass of an protons plus protons. This element’s atom neutrons. defines the based on isotopes. element. -*atomic mass unit (neutrons are slightly more than 1amu)
  7. 7. - Atomic number is the number of protons. 2 He+ helium + 4.00 Atomic mass is the mean mass of an element’s atom based on isotopes. Different periodic tables place the atomic number, atomic mass and mass number in - different positions, so pay attention to the key.
  8. 8. What’s this? ? + ? ? ?
  9. 9. What’s this? An atom of hydrogen has one proton and one electron only. 1 + H hydrogen 1.01 Why the 1.01? In nature some isotopes of hydrogen exist. These have 1 neutron (deuterium, mass 2amu) or 2 neutrons (tritium, mass 3amu) How would you change the diagram to show each of these isotopes?
  10. 10. What’s the mean numberof legs per person in:• this class?• the world? Image: Stacked http://www.flickr.com/photos/17731548@N00/2153132167 Found on flickrcc.net
  11. 11. What’s the mean numberof legs per person in:• this class?• the world?Slightly less than one!Why? Image: Stacked http://www.flickr.com/photos/17731548@N00/2153132167 Found on flickrcc.net
  12. 12. What’s this? ? + ? ? ?
  13. 13. What’s this? This ion of hydrogen has one proton only. An electron has been lost. 1 + H + hydrogen 1.01 The overall charge of this ion is +1. It is a cation.
  14. 14. - What do you think? + + + It has 2 e-, but 3n0, so it must- be an isotope of helium It has 3 p+, so it must be an ion of lithium It has 2 e-, so it must be helium
  15. 15. - + + + -What do these represent? - + + + -
  16. 16. - + + + -An atom of hydrogen has one proton An atom of helium has two protons,and one electron only. two neutrons and two electrons. - + + + -An ion of hydrogen has one This isotope of helium has two protons,proton only – and therefore an one neutron and two electrons.overall charge of +1
  17. 17. mass number = 12 13 What do you ? ? think?atomic number = 6 Charge = 0 6 Charge = 0 They are both the same element, but have different mass numbers, so one must be an ion. The atomic mass of the second element is 13, so it must be aluminium Its atomic number is 6, so they must both be carbon
  18. 18. Marshmallow Isotopes neutrons 1. Make a hydrogen nucleus (a proton). nucleons 2. Make an alpha particle (helium nucleus) protons Use a lick to stick. Sticking forces in nuclei are weak. What are they? You need white and pink marshmallows This is called helium-4, as it has four nucleons. 3. Make a particle of the isotope helium-3. + What is different? + 4. He-5 is an unstable isotope. The alpha-particle Make it and then suggest why it is unstable. 5. C-12 is the main stable isotope of carbon. Make it. What other isotopes of carbon are there? What are their uses? 6. In the first few minutes of the universe, alpha particles formed. New elements can be made from combining alpha particles. Combine your He-4 with a C-12. What element have you made?Adapted from: http://www.lbl.gov/abc/marsh-nuclei/index.html Image from http://www.hancocks.co.uk/
  19. 19. Neutrons determine nuclear propertiesHave a go at this at home if you need more consolidation on isotopes, neutrons and mass number. Recreate some of the atoms and isotopes you made in the marshmallow activity. How does neutron number affect mass number of the atom? Are all isotopes of an element equally abundant in nature? What is nuclear ‘stability’?Isotopes & Atomic Mass, from PhET. Click Run Now.http://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass The number of neutrons does not always equal the number of protons in a stable element. As proton number increases, an increasing number of neutrons is needed to keep the atom stable. If there are too many or too few neutrons, it is unstable.
  20. 20. Not all periodic atomic numbertables organise thenumbers around theelements in the sameway. mass number symbolYou must pay nameattention to the key!
  21. 21. mass number = 127 131 What do you ? ? think?atomic number = 53 Charge = 0 53 Charge = 0Check the key! They are both isotopes of iodine. They have different numbers of neutrons and protons. They are both isotopes of iodine. They have different numbers of neutrons. They have the same atomic numbers but different mass numbers. They are ions.
  22. 22. Iodine has many isotopes. mass number = 127 131 I Iatomic number = 53 Charge = 0 53 Charge = 0 Iodine-127 Iodine-131 Protons: 53 Protons: 53 Neutrons: 74 Neutrons: 78 Stable Unstable Radioisotope used in treating Abundant Artifical thyroid cancer.The number of neutrons does not always equal the number of protons in a stableelement. As proton number increases, an increasing number of neutrons is neededto keep the atom stable. If there are too many or too few neutrons, it is unstable.
  23. 23. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 ? 1 Charge = +1
  24. 24. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 H ? 1 Charge = +1 92 Charge = 0 H+ ion
  25. 25. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 H U ? 1 Charge = +1 92 Charge = 0 92 Charge = 0 H+ ion Uranium
  26. 26. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U ? 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope
  27. 27. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U Co 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope Cobalt isotope 16 ? 8 Charge = 2-
  28. 28. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U Co 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope Cobalt isotope 16 238 O ? 8 Charge = 2- 94 Charge = 0 Oxygen ion
  29. 29. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U Co 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope Cobalt isotope 16 238 40 O Pu ? 8 Charge = 2- 94 Charge = 0 20 Charge = 2+ Oxygen ion Plutonium isotope
  30. 30. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U Co 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope Cobalt isotope 16 238 40 47 O Pu Ca ? 8 Charge = 2- 94 Charge = 0 20 Charge = 2+ 20 Charge = 0 Oxygen ion Plutonium isotope Calcium ion
  31. 31. mass number = 12 Atom, Ion or C Isotope?atomic number = 6 Charge = 0 1 238 235 60 H U U Co 1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0 H+ ion Uranium Uranium isotope Cobalt isotope 16 238 40 47 O Pu Ca Ca 8 Charge = 2- 94 Charge = 0 20 Charge = 2+ 20 Charge = 0 Oxygen ion Plutonium isotope Calcium ion Calcium isotope
  32. 32. What are they? How do we draw them? IONSHow do we name them? How do they make bonds?
  33. 33. Electrons determine chemical properties An atom of helium has two protons, two neutrons and two electrons. - It is a small atom, with an electron ‘shell’ which 2p+ can hold only 2 electrons. 2n0 Because the ‘shell’ is full, He is stable and - unreactive – it is a noble gas. The inner shells ‘fill’ first, as the electrons are - - attracted to the positive nucleus. - Larger atoms have bigger shells. However, the outermost shell holds maximum 8 electrons. 9p+ - - 9n0 - What is this atom? How might it become more stable? - - -
  34. 34. Ions have unbalanced protons and electrons - H atom 1p+ 0n0 - - - F atom 9p+ - - 9n0 - - - -
  35. 35. Ions have unbalanced protons and electrons H+ ion 1p+ 0n0 Positively charged ions are cations. (Think: cats make old ladies happy) - - - F- ion - 9p+ - Negatively charged ions are anions. - 9n0 - (Think: A Negative ION) - - -
  36. 36. Octet Rule Atoms in a compound will tend to have the electron configuration of a noble gas: Eight electrons in the outer (valence) shell. Duet RuleThe inner shell can hold a maximum two electrons – the configuration of helium.
  37. 37. Atoms and the periodic table Group 1: Alkali metals columns Group 2: Alkaline earth metals are groups Group 7: Halogens (sometimes called 17) Group 8: Noble gases (sometimes 18 or 0) orphan hydrogenrows are periods Lanthanides Actinoids Interactive periodic table from: http://www.ptable.com/
  38. 38. Ions have unbalanced protons and electrons Common ions: Positively charged ions are cations. Negatively charged ions are anions. (Think: cats make old ladies happy) (Think: A Negative ION) What’s the difference between the ions in purple and those in black? Compare the elemental ions to the periodic table. Can you describe a trend? Can you explain why the elements above form these specific ions?
  39. 39. What’s the relationship between atomic structure and the periodic table? +1 +2 Ionic charges are in red. +3 -3 -2 -1 metals non-metals transition metalsPeriodic Table from the IBDP Chemistry Data Booklet
  40. 40. What’s the relationship between atomic structure and the periodic table?Interactive periodic table from: http://www.footprints-science.co.uk/flash/periodic2.swf
  41. 41. Atoms and the periodic table Group 1: Alkali metals columns Group 2: Alkaline earth metals are groups Group 17: Halogens Group 18: Noble gases orphan hydrogenrows are periods Lanthanides Actinoids Interactive periodic table from: http://www.ptable.com/
  42. 42. Valence Electrons & ConfigurationsIn the first period (H and He), there is onesmall electron shell. It can hold up to twoelectrons – a duet.As we move down each period, weadd an electron shell.The outer shell can holdup to 8 electrons. 4 shells, 1 valence electronValence electrons are the electrons inthe outer shell only. They are used inbonding.Once the outer shell is full, the atom isstable. This is the octet rule. Interactive periodic table from: http://www.ptable.com/
  43. 43. Complete the pattern… H He Li Be B C N O F NeWhat do the dots represent?What is the relationship with periodic table?Can you predict the pattern for aluminium?
  44. 44. Lewis dot configurations These dots show the number of valence electrons in an atom. H We can use them to predict bond types as well as the He structure of a compound. Li Be B C N O F NeWhat is the relationship with periodic table?Elements in the same group have the same All the Lewis dots:number of valence electrons.Can you predict the pattern for aluminium? Al http://www.roymech.co.uk/Related/Chemistry/Lewis_dot_structure.html
  45. 45. What’s in your sports drinks? Sports drinks contain ions to help with rehydration (if you really need it). Two of their main ingredients are sugar (sucrose) and salt (sodium chloride). In this investigation we will: • Determine whether sugar or salt is ionic • Compare the ion concentrations of two drinks https://docs.google.com/presentation/d/1Hqs6AMjlx5KBGWWSzOLBSBbO2mzDqw17CkMSdB hSAcQPocari Sweat and Aquarius bottles fromhttp://jin.jcic.or.jp/en/ranking/near_water_small_pet_bottle_pouch/
  46. 46. Bonding is the attraction between atoms. Atoms are stable when they have a full valence shell. In ionic bonds, electrons are transferred to achieve this. In covalent, electrons are shared. The result are forces of attraction. Bonds: • Ionic • Covalent • Metallic Inter-molecular forces: • Dipole-dipole bonds • Hydrogen bonds • Van der Waal’s forceshttp://www.kentchemistry.com/links/bonding/bondingflashes/bond_types.swf
  47. 47. Ionic or covalent bonds? Binary compounds contain two elements. Metal + non-metal, the bonding will be ionic. If both are non-metals, bonding is covalent. non-metals metals So what about these compounds? lithium fluoride _____________ nitrogen dioxide _____________ carbon dioxide _____________ water _____________ magnesium oxide ____________ methane (CH4) _____________ sodium chloride _____________ lead iodide _____________Periodic table from the BBC. http://goo.gl/1rrCk
  48. 48. Ionic or covalent bonds? Binary compounds contain two elements. Metal + non-metal, the bonding will be ionic. If both are non-metals, bonding is covalent. non-metals metals So what about these compounds? lithium fluoride ionic nitrogen dioxide covalent carbon dioxide covalent water covalent magnesium oxide ionic methane (CH4) covalent sodium chloride ionic lead iodide ionicPeriodic table from the BBC. http://goo.gl/1rrCk
  49. 49. Octet Rule Atoms in a compound will tend to have the electron configuration of a noble gas: Eight electrons in the outer (valence) shell. Duet RuleThe inner shell can hold a maximum two electrons – the configuration of helium.
  50. 50. Ionic Bonding Forms between a metal and a non-metal. Metal cations(+) donate electron(s) to non- metal anions(-). Li F + - cation Li F anion The metal has lost its lone electron and the non-metal has gained. They each now have filled outer valence shells. Cations attract anions – the atoms are held together by this attraction – the ionic bond. + - Li Fhttp://www.footprints-science.co.uk/ionic.htm
  51. 51. Almost full? Get some more. Almost empty? Get rid.Draw the electron arrangements on these shells.State the number of valence electrons and draw a Lewis dot configuration.Deduce whether they will form an anion or a cation. Oxygen Chlorine Aluminium Beryllium
  52. 52. Almost full? Get some more. Almost empty? Get rid.Draw the electron arrangements on these shells.State the number of valence electrons and draw a Lewis dot configuration.Deduce whether they will form an anion or a cation. Oxygen Chlorine 8 protons, 8 electrons, 6 valence electrons. Lewis dot: O 2- O Almost full- gain two electrons and form an anion. Aluminium Magnesium Al
  53. 53. Almost full? Get some more. Almost empty? Get rid.Draw the electron arrangements on these shells.State the number of valence electrons and draw a Lewis dot configuration.Deduce whether they will form an anion or a cation. Oxygen Chlorine 8 protons, 8 electrons, 6 valence electrons. Lewis dot: O 2- O Almost full- gain two electrons and form an anion. Aluminium Magnesium 13 protons, 13 electrons, Al 3 valence electrons. Lewis dot: Al 3+ Al Almost empty- lose three electrons and form a cation.
  54. 54. Ionic Bonding Cations Anions +1 +2 +3 -3 -2 -1 + 2+ 3+ 3- 2- - H Mg Al N O Cl Li+ Ca2+ Fe3+ P3- S2- Br-In an ionic bond, the charges must balance. + 2+ 3- 2- - Na Fe PO4 CO3 IIons can be elemental or polyatomic – it is K + Cu 2+ SO4 2- NO3 -the charge which matters. NH4 + Zn 2+ HCO3 - 2+ - Pb OHWhat combinations of ions are needed tomake the following compounds? • Sodium chloride one of each ion gives a • Lithium iodide Na+ Cl- balanced charge • Calcium carbonate • Sodium hydroxide • Iron (III) oxide Ionic bonding works in 3-D, so ionic compounds form crystal structures. They are strong and can form aqueous solutions. They are good electrical conductors when dissolved or molten.
  55. 55. Ionic Bonding Cations Anions +1 +2 +3 -3 -2 -1 + 2+ 3+ 3- 2- - H Mg Al N O Cl Li+ Ca2+ Fe3+ P3- S2- Br-In an ionic bond, the charges must balance. + 2+ 3- 2- - Na Fe PO4 CO3 IIons can be elemental or polyatomic – it is K + Cu 2+ SO4 2- NO3 -the charge which matters. NH4 + Zn 2+ HCO3 - 2+ - Pb OHWhat combinations of ions are needed tomake the following compounds? • Sodium chloride • Lithium iodide Na+ Cl- Fe3+ Fe3+ • Calcium carbonate • Sodium hydroxide balance the charges: 6+ and 6- • Iron (III) oxide O2- O2- O2- Ionic bonding works in 3-D, so ionic compounds form crystal structures. They are strong and can form aqueous solutions. They are good electrical conductors when dissolved or molten. http://en.wikipedia.org/wiki/Iron(III)_oxide
  56. 56. Ionic Bonding Cations Anions +1 +2 +3 -3 -2 -1 + 2+ 3+ 3- 2- - H Mg Al N O Cl Li+ Ca2+ Fe3+ P3- S2- Br-Practice drawing Lewis dot structures for + 2+ 3- 2- - Na Fe PO4 CO3 Ithese ionic bonds: K + Cu 2+ SO4 2- NO3 - + 2+ - NH4 Zn HCO3 • hydrogen chloride Pb 2+ OH - • iron (II) oxide • potassium iodide • copper sulphide (CuS) • potassium nitride
  57. 57. Metallic BondingIn bonds between metal atoms, electronsbecome delocalised and move freely.This makes them very malleable andductile. Freely-moving electrons makesthem very good electrical conductors. From GCSE Bitesize: http://goo.gl/tJlVP Animation from: http://www.drkstreet.com/resources/m etallic-bonding-animation.swf
  58. 58. The duet and octet rules Hydrogen and helium follow the duet rule – two valence electrons. They have a small H H outer electron shell. H2 (H-H) H H H H Single covalent bond shared the line represents electrons a pair of electrons.
  59. 59. The duet and octet rules Hydrogen and helium follow the duet rule – two valence electrons. They have a small H H outer electron shell. H2 (H-H) H H H H Single covalent bond shared the line represents electrons a pair of electrons.Other elements follow the octet rule.They will gain, lose or share electronsuntil the outer shell has a full set of 8. O OWe can work out how bonds will form byadding up the total number of valence O2 (O=O)electrons and distributing them. O O O OTwo oxygen atoms have a total of 12 valenceelectrons. By sharing them in covalent bonds, shared sharedthey can make up the 8 needed. electrons electrons Double covalent bond each line represents a pair of electrons.
  60. 60. Diatomic molecules These are molecules which are found as pairs of atoms, H H sharing electrons. They can be elements or compounds. H2 See if you can draw Lewis dot configurations for these diatomic molecules. H H F F Cl Cl Br Br O O F2 Cl2 Br 2 O2 O O N I I NN I2 2
  61. 61. Covalent BondingForms between non-metals.Atoms share valence electrons in the outer shell.They do not form large crystals like ionic compounds. http://www.visionlearning.com/library/mA single bond is the force between odule_viewer.php?mid=55 (animation)two atoms which are sharing two electrons, e.g. H-H.Double bonds are formed whentwo atoms share four electrons, such as O=O.Water is an example of a polar covalent bond.Oxygen has more protons and pulls the sharedelectrons more strongly.The electrons are not σ-shared equally. http://www.allthingsscience.com/video/849/Ionic-The oxygen side is slightly O and-covalent-bonding-animationnegative and thehydrogens areslightly positive. H H σ+ σ+ σ = “slightly”
  62. 62. Only covalently-bonded compoundscan be accurately called ‘molecules’.Ionic compounds interact in crystals.
  63. 63. Covalent Bonding Non-metals will share electrons when they bond. How many electrons does oxygen have in total? O How many of these are valence electrons? How about hydrogen? Draw them on. Draw a Lewis Dot structure for each. H
  64. 64. Covalent Bonding Non-metals will share electrons when they bond. Oxygen: 8 electrons, 6 valence electrons. Hydrogen: 1 electron, 1 valence electron. O O H Oxygen follows the octet rule and needs eight valence electrons to be stable. H Hydrogen follows the duet rule and needs two. It has one already, so will share it with oxygen.
  65. 65. Covalent Bonding Non-metals will share electrons when they bond. H O Oxygen follows the octet rule and needs eight valence electrons to be stable. H O Hydrogen follows the duet rule and needs two. It has one already, so will share it with oxygen. Now the hydrogen has a full valence shell… … but the oxygen is one short.
  66. 66. Covalent Bonding Non-metals will share electrons when they bond. H H O H Another hydrogen atom can share the final electron needed to fill the valence shell of oxygen. H O This gives water – H2O!
  67. 67. Polar Bonds Larger atoms exert a greater pull on shared electrons. Oxygen has more protons than hydrogen. This means there is a stronger attraction between the shared electrons and oxygen than there is with the nucleus of hydrogen. The result is a polar bond. Electrons are pulled slightly closer to the oxygen, making it slightly negatively charged overall. The hydrogen ends up σ+ slightly positively charged.σ = “slightly” This will happen in any covalently-bonded molecule where there is a big difference in atomic σ+ numbers. The bigger the difference, the stronger the effect. σ-
  68. 68. Hydrogen Bonding This is really an inter-molecular force σ- between polar molecules. It is a dipole-dipole attraction O involving H-O, H-F or H-N bonds. Electrons in covalent bonds can be unevenly shared, Animation from Sumanas: H H http://goo.gl/rblz1 making the molecule polar. σ+ σ+ These slight charges will attract opposites, such as in water and DNA! hydrogen bond σ = “slightly” σ- http://dna.microbiologyguide.com/s/10002/pics/dnabases.gif
  69. 69. Water molecules are attracted to each other with hydrogen bonds. σ- O H H σ+ σ+ hydrogen bond σ = “slightly” σ-
  70. 70. The polar nature of water allows it to act as a solvent for ionic solids.Annotate this model of water dissolving NaCl.
  71. 71. Carbon dioxide C C O O O O
  72. 72. Carbon dioxide: double bonds O C O C Two double bonds are formed. These are shorter and stronger shared O than single bonds. electrons shared electrons O C O Bonds and electrons can also be By forming a double bond with each oxygen represented with these lines. atom, carbon has shared four more electrons Each line represents two electrons. in its valence shell and is stable.
  73. 73. Carbon monoxide: triple bonds C O C One triple bond is formed. These are shorter and stronger than single and double bonds. The oxygen atom shares four electrons and the carbon shares two. This gives six shared electrons – a triple bond. O C Bonds and electrons can also be represented with these lines. Each line represents two electrons.
  74. 74. Van der Waal’s ForcesWhen non-polar molecules come in very close contact witheach other, an attractive force called Van der Waal’s force canbe created. This is because an induced dipole is created.It is is a very weak inter-molecular force,but the cumulative total of Van der Waal’sforces can be quite strong.Gecko feet are thought to use VdW’s forces.They have thousands of tiny hairs called spatulae,which maximise the surface area for forces to act. 1μm Read about how geckoes use Van der Waal’s forces here: http://news.bbc.co.uk/2/hi/science/nature/781611.stm
  75. 75. Assessment: Knowledge and UnderstandingMrT will give you two elements and the conclusion of a fictitious student.Using all of your knowledge from Atoms and Bonding, explain how they will bond.Analyse and evaluate the student’s conclusion.Work through these steps: • Draw atomic structure diagrams of each • Identify the number of valence electrons • Draw Lewis dot structures • State whether they will bond ionically or covalently and why. • If they bond ionically, explain which will form an anion and which will forma cation and why. • Draw diagrams to show how they will bond • Show the final Lewsis Dot structures and state whether the bonds are single, double or triple and why. • If they bond covalently, try to determine if they will form a polar bond and identify which part will be positive and which negative, and why.Submit this on a separate piece of paper, along with this worksheet. It will be assessed forcriterion C: Knowledge and Understanding.
  76. 76. A H B C O O HH O H O D H HE F G + H 2- H H H O
  77. 77. σ- O H Hσ+ σ+ hydrogen bond σ = “slightly” σ-
  78. 78. One World Issues: Group Poster TaskExplain the problem and outline how the use of Explain how the A-bomb workedthe bomb was thought to be a solution. and was used.Identify the stakeholders. Evaluate and discuss theWho are all the people or groups who were implications of the bomb.affected in some way by the use of the bomb? Discuss the use of the bomb, from multiple perspectives, for each of these One World issues: social moral ethical political environmental economic cultural This will help you write your own personal essay on One World in Chemistry…
  79. 79. How do we use these radioisotopes? Quick research and presentation: - What is it and how is it an isotope? - What is it used for? - HOW is it used for this purpose? Uranium-235 Cesium-137 Cobalt-60
  80. 80. Criterion A: One World “The role of radioisotopes in Science.”Level Level descriptor 0 The student does not reach a standard described by any of the descriptors below. 1–2 The student states how science is applied and how it may be used to address a specific problem or issue in a local or global context. The student states the effectiveness of science and its application in solving the problem or issue. 3–4 The student describes how science is applied and how it may be used to address a specific problem or issue in a local or global context. The student describes the effectiveness of science and its application in solving the problem or issue. The student describes the implications of the use and application of science interacting with at least one of the following factors: moral, ethical, social, economic, political, cultural and environmental. 5–6 The student explains how science is applied and how it may be used to address a specific problem or issue in a local or global context. The student discusses the effectiveness of science and its application in solving the problem or issue. The student discusses and evaluates the implications of the use and application of science interacting with at least two of the following factors: moral, ethical, social, economic, political, cultural and environmental.Criterion B: Communication in ScienceLevel Level descriptor 0 The student does not reach a standard described by any of the descriptors below. 1–2 The student uses a limited range of scientific language correctly. The student communicates scientific information with limited effectiveness. When appropriate to the task, the student makes little attempt to document sources of information. 3–4 The student uses some scientific language correctly. The student communicates scientific information with some effectiveness. When appropriate to the task, the student partially documents sources of information. 5–6 The student uses sufficient scientific language correctly. The student communicates scientific information effectively. When appropriate to the task, the student fully documents sources of information correctly.
  81. 81. Ions have unbalanced protons and electrons Common ions: Cations Anions +1 +2 +3 -3 -2 -1 + 2+ 3+ 3- 2- - H Mg Al N O Cl Li+ Ca2+ Fe3+ P3- S2- Br- + 2+ 3- 2- - Na Fe PO4 CO3 I + 2+ 2- - K Cu SO4 NO3 + 2+ - NH4 Zn HCO3 2+ - Pb OH Positively charged ions are cations. Negatively charged ions are anions. (Think: cats make old ladies happy) (Think: A Negative ION) What’s the difference between the ions in purple and those in black? Compare the elemental ions to the periodic table. Can you describe a trend? Can you explain why the elements above form these specific ions?
  82. 82. What do you think? Ideas based on Concept Cartoons: http://www.conceptcartoons.comClipart people from: http://www.clker.com/search/krug/1
  83. 83. South-West A South-West BSouth-East A South-East BNorth-East A North-East BNorth-West A North-West B MrT’s Chemistry Shop
  84. 84. @IBiologyStephen Please consider a donation to charity via Biology4Good. Click here for more information about Biology4Good charity donations. This is a Creative Commons presentation. It may be linked and embedded but not sold or re-hosted.

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