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Periodicity Mr Field Using this slide show The slide show is here to provide structure to the lessons, but not to limit them….go off-piste when you need to! Slide shows should be shared with students (preferable electronic to save paper) and they should add their own notes as they go along. A good tip for students to improve understanding of the calculations is to get them to highlight numbers in the question and through the maths in different colours so they can see where numbers are coming from and going to. The slide show is designed for my teaching style, and contains only the bare minimum of explanation, which I will elaborate on as I present it. Please adapt it to your teaching style, and add any notes that you feel necessary. Main Menu Menu: Lesson 1 – The Periodic Table Lesson 2 – Physical Properties Lesson 3 – Chemical Trends Lesson 4 – The Period 3 Oxides Lesson 5 – HL – The Period 3 Oxides and Chlorides Lesson 6 – HL – Transition Metals - Introduction Lesson 7 – HL – Coloured Complexes and Catalysts Lesson 8 – Test Lesson 9 – Test Debrief Main Menu Lesson 1 The Periodic Table Main Menu Overview Copy this onto an A4 page. You should add to it as a regular review throughout the unit. Main Menu Assessment This unit will be assessed by: A test at the end of the topic (100%)…around Lesson 8 Main Menu We Are Here Main Menu Lesson 1: The Periodic Table Objectives: Reflect on prior knowledge of the periodic table Understand the structure and purpose of the periodic table Repeat the work of Mendeleev by constructing your own periodic table Main Menu Reflecting on the Periodic Table What is the periodic table and what is supposed to show? Main Menu The Traditional Based on Mendeleev’s work. Easiest to use and display. Main Menu Dmitri Mendeleev’s Periodic Table The one that started it all off. Main Menu Wide Format Periodic Table Shows true position of the f-block (lanthanides and actinides) Main Menu Janet Periodic Table Elements arranged in order of orbital filling. Used frequently by physicists. Main Menu Benfey Periodic Table Spiral form shows the steady increase in atomic number. Main Menu Stowe Periodic Table Emphasises the symmetrical nature of the increase in quantum numbers. Main Menu Zymaczynski Periodic Table Another way to show the symmetry in the underlying quantum numbers. Main Menu Giguere Periodic Table A 3D representation emphasising the s, p, d and f blocks Main Menu The Structure of the Periodic Table GROUPS PERIODS Main Menu Groups and Periods Groups Elements show similar chemical properties Elements show similar trends in their chemical properties Periods As you move across periods, changes in the chemical and physical properties that are repeated in the next period This is what ‘period’ and ‘periodic’ refers to Main Menu The periodic table and electron configuration How does an element’s position in the PT relate to its electron configuration? Main Menu Being Mendeleev The first widely accepted periodic table was produced by the Russian chemist Dmitri Mendeleev It was a tremendous example of scientists as risk-takers as it was able to make a number of predictions thought unlikely at the time Complete the exercise here in which you will use the information available to Mendeleev to construct your own periodic table Main Menu Homework – HL only! In two groups, you need to work together to plan a 30 minute lesson on the objectives detailed below to be delivered in Lesson 5. The lesson should include: A presentation Complete with equations, diagrams, explanations etc An activity A review Allocations: Oxides: Na2O, MgO, Al2O3, SiO2, P4O6 and P4O10, SO2 and SO3, Cl2O and Cl2O7 Group 1: Explain the physical states (under standard conditions) and electrical conductivity (in the molten state) of the chlorides and oxides of the elements in period 3 in terms of their bonding and structure. Group 2: Describe the reactions of chlorine and the chlorides referred to above with water. State and explain the acidity of the resulting solutions Main Menu Chlorides: NaCl, MgCl2, Al2Cl6, SiCl4, PCl3 and PCl5, and Cl2 SUPER IMPORTANT (If you have one) bring a laptop with spreadsheet program to the next lesson. If you don’t have Microsoft Excel, download OpenOffice for free from: www.openoffice.org Main Menu Key Points The periodic table arranges the elements according to: Their chemical properties Their electronic structure Main Menu Lesson 2 Physical Properties Main Menu Refresh Nitrogen and silicon belong to different groups in the periodic table. a) Distinguish in terms of electronic structure, between the terms group and period. b) State the maximum number of orbitals in the n = 2 energy level. Main Menu We Are Here Main Menu Lesson 2: Physical Properties Objectives: Identify and explain the trends in the physical properties of the first 20 elements including: Atomic radius Ionic radius First ionisation energy Electronegativity Melting point Use Microsoft Excel to produce a spreadsheet to graph the above physical data Main Menu Atomic Radius This is the ‘size’ of an atom There is no simple measure as atoms do not have a well defined ‘edge’ We use the: covalent radius Values range from are measured in picometres ( 1 pm = 1x10-12 metres…a thousand-billionth of a metre) and range over: This is half the distance between the nuclei of two atoms in a covalent bond This means we don’t have values for the noble gases as they do not form bonds 270 picometres Francium 30 picometres for Hydrogen (helium would be smaller but does not form covalent bonds to be measured) The main factors influencing atomic radius are: Number of shells (the principal quantum number) The charge in the nucleus Main Menu Ionic Radius This is the ‘size’ of an ion and is measured in a similar way to atomic radius It is measured in a picometres with values ranging over: 272 pm for the Ge4- ion 16 pm for the B3+ ion The main factors influencing ionic radius are: Number of shells (the principal quantum number)…don’t forget this can be affected by the type of ion formed The charge in the nucleus Main Menu First ionisation energy This is the energy required to remove one mole of electrons from one mole of gaseous atoms to form positive ions i.e.: A(g) A+(g) + e- Values range over: 393 kJ mol-1 for Caesium 1681 kJ mol-1 for Helium Values are positive because this is an endothermic process Values are influenced by: Number of inner electron shells (and their shielding) Charge on the nucleus HL: At the finest level – repulsion between electrons in their orbitals Main Menu Electronegativity This is a measure of the degree to which an element attracts the shared pair of electrons in a covalent bond Values range over: 4.0 for Fluorine 0.7 for Francium Values are influenced by: Again, this means there are no values for the noble gases Number of inner electron shells (and their shielding) Charge on the nucleus Values are unit-less as this is a relative measure Main Menu Melting Point This is the temperature (in Kelvin…i.e. Celsius + 273) at which an element melts Values range over: 3935 K for Carbon 1 K for Helium Values are influenced by: Nature of bonding: giant covalent, giant ionic, metallic Strength of bonding Strength of intermolecular forces Main Menu Trends in Physical Properties You need to produce an Excel spreadsheet to help you analyse the physical data. Use the blank here and follow the instructions on the instructions page Once you have done this you need to use this to help you identify and explain the following trends: Atomic and ionic radius, first ionisation energy, electronegativity and melting point Atomic and ionic radius, first ionisation energy, electronegativity Down group I (alkali metals) Down group VII (halogens) Across period 3 The general trend in electronegativity over the whole PT Main Menu Key Points Each of the following physical parameters follow trends and patterns in the PT These patterns are generally explained by: Charge in the nucleus Number of electron shells Electron shielding Main Menu Lesson 3 Chemical Properties Main Menu Refresh Which species has the largest radius? Do not use the data booklet…work it out! A. B. C. D. Cl– K Na+ K+ Main Menu We Are Here Main Menu Lesson 3: Chemical Properties Objectives: Understand the following trends in reactivity: Alkali metals with water Alkali metals with halogens Halogens with halide ions Complete an experiment to investigate the above Main Menu Chemical Trends Members of a group often have very similar reactivity. You probably know that carbon will react with hydrogen to form methane, CH4 You probably did not know that silicon will also react with hydrogen to form silane, SiH4 Watch this demonstration to see some silane being made Main Menu Three reactions to know The Group I (alkali) metals react with water as follows: The Group I (alkali) metals react with halogens (Group VII) as follows: Metal + Water Metal Hydroxide + Hydrogen Metal + Halogen Metal Halide Halogens can react with halide ions as follows (using the example of bromide and chlorine): Bromide + Chlorine Chloride + Bromine Main Menu Investigating chemical trends In this experiment you will investigate trends in the reactions mentioned on the previous slide Follow the instructions here Main Menu Key Points Alkali metals become more reactive down the group: Due to the outer shell electron becoming increasingly easy to remove Halogens become less reactive down the group: Due to the increased numbers of electron shells (and thus shielding) causing them to attract electrons less strongly Main Menu Lesson 4 Period 3 Oxides Main Menu Refresh Which properties of the alkali metals decrease going down group 1? A. B. C. D. First ionization energy and reactivity Melting point and atomic radius Reactivity and electronegativity First ionization energy and melting point Main Menu We Are Here Main Menu Lesson 4: Period 3 Oxides Objectives: Understand and explain the trend in acid-base behaviour of the period 3 oxides Complete an experiment to demonstrate the amphoteric nature of aluminium oxide Main Menu The Period 3 Oxides Element Formula of oxide Reaction of oxide with water Acid/base nature Sodium* Na2O Na2O + H2O 2NaOH Strongly basic Magnesium* MgO Slight: MgO + H2O Mg(OH)2 Weakly basic Aluminium Al2O3 Amphoteric Silicon SiO2 Very weakly acidic Phosphorous* P4O10 Sulphur* SO2 SO3 Chlorine Argon no direct reaction but: Cl2O7 P4O10 + 6 H2O 4 H3PO4 Strongly acidic Strongly acidic SO3 + H2O H2SO4 Strongly acidic Cl2O7 + H2O 2 HClO4 no oxides There is a gradual transition from basic to acidic character, reflecting a gradual transition from metallic to non-metallic nature Note: you will only be tested on the elements marked with an asterisk, * Main Menu Amphoteric Aluminium Complete the amphoteric aluminium experiment here. This goes beyond the requirements of the syllabus but will help deepen your knowledge and understanding. Main Menu Homework Research the role of acidic oxides in the formation of acid rain. Include: Sources of acidic oxides Names and formulas and their reactions with water Main Menu Key Points The oxides of period 3 display a gradual transition basic to acidic character This reflects a gradual transition from metallic to non-metallic nature of the elements Main Menu Lesson 5 Period 3 Oxides and Chlorides Main Menu Refresh Which oxides produce an acidic solution when added to water? I. II. III. A. B. C. D. P4O10 MgO SO3 I and II only I and III only II and III only I, II and III Main Menu We Are Here Main Menu Lesson 5: Period 3 Oxides Objectives: Complete the amphoteric aluminium activity Deliver the lessons set for homework in the first lesson of the topic Main Menu Amphoteric Aluminium Complete the experimental work for the amphoteric aluminium activity – you have 25 minutes Main Menu Over to you Welcome to my world! Main Menu Homework Complete the analysis for the amphoteric aluminium activity Main Menu Lesson 6 Transition Metal Complexes - Introduction Main Menu Refresh By reference to the structure and bonding in NaCl and SiCl4: a) State and explain the differences in electrical conductivity in the liquid state. b) Predict an approximate pH value for the solutions formed by adding each compound separately to water. Explain your answer. Main Menu We Are Here Main Menu Lesson 6: Transition Metal Complexes Introduction Objectives: Describe the properties of transition metals Understand the term ligands Understand and explain the formation of transition metal complexes Main Menu The Transition Metals A transition metal is an element in which at least one ion has a partially filled d-orbital For example, Cu2+: 1s2 2s2 2p2 3s2 3p2 (4s0) 3d9 Properties of the transition metals include: Variable oxidation states (for example iron: Fe2+, Fe3+, Fe6+) Formation of coloured compounds (more later) Catalytic properties (more later) Formation of complex ions (much more later) Main Menu Scandium and Zinc Although in the first row of the d-block, these are not transition metals. To understand why, write the full electron configuration for: Sc and Sc3+ Zn and Zn2+ Main Menu Variable oxidation numbers (ions) Transition metals have large numbers of electrons in d-orbitals, Some common oxidation states we need to know: This means the amount of energy required to remove the second electron is not much different to that required to remove the first and so on. All of them in the +2 oxidation state Cr(III), Cr(VI) Mn(IV), Mn(VII) Fe(III) Cu(I) Task: select 4 of these and write the electron configuration Main Menu Ligands A ligand is a species with a lone pair Often negative ions Common ligands include: Water, H2O Ammonia, NH3 Chloride, ClHydroxide, OHCyanide, CNThiocyanate, SCNMain Menu Transition Metal Complexes The lone pair on a ligand can form a dative covalent bond to a metal ion to form a transition metal complex [Fe(H2O)6]3+ [Fe(CN)6]3- [Cu(Cl)4]2- [Ag(NH3)2]+ Main Menu Making transition metal complexes Add potassium thiocyanate solution to a solution of iron (III) Add conc. HCl (fume hood!) to 1 cm3 of a strong solution of cobalt (II). Repeat but use conc. NH3 instead (fume hood!). Add dilute NH3 to a copper (II) solution until no further change occurs Record all observations Suggest possible structures for the complexes you have formed and possible reaction equations Main Menu A Challenge Working in small groups, complete the following activity on the structure of some cobalt complexes. Main Menu Key Points Transition metals form ions with partially filled d-orbitals Ligands are species with lone pairs Ligands will form dative covalent bonds to transition metals forming ‘complex ions’ Main Menu Lesson 7 Complex Colours and Catalysts Main Menu Refresh By reference to the structure and bonding in NaCl and SiCl4: a) State and explain the differences in electrical conductivity in the liquid state. b) Predict an approximate pH value for the solutions formed by adding each compound separately to water. Explain your answer. Main Menu We Are Here Main Menu Lesson 7: Complex Colours and Catalysts Objectives: Complete the amphoteric aluminium activity Deliver the lessons set for homework in the first lesson of the topic Main Menu Marketplace – in three groups Each group needs to produce a learning resource to teach the other students about their chosen topic. Once the resources are completed, one person should remain with the resource whilst the remaining members circulate and learn from the other stations….you should manage your time, taking turns manning your station to make sure everyone makes it round class. The catalysts topics should include the names of the elements/compounds, an equation for the reaction they do and the importance of the catalysis. There will be a test at the end. Topic allocations: Origin of colour in transition metal complexes (d-orbital splitting) Catalysts 1: Transition metal Catalytic converters, conversion of alkenes to alkanes, the Haber process Catalysts 2: Transition metal compounds: Decomposition of hydrogen peroxide, Contact process, haemoglobin, vitamin B12 Main Menu Test time You have 10 minutes Mwahahahahahahahahaha Main Menu Key Points The formation of complexes causes d-orbitals to split into two energy levels Electron transitions between these energy levels give rise to their colour Transition metals are hugely important for their catalytic properties Main Menu Lesson 8 Test Main Menu Good Luck You have 80 minutes! Main Menu Lesson 9 Test Debrief Main Menu Personal Reflection Spend 15 minutes looking through your test: Make a list of the things you did well Use your notes and text book to make corrections to anything you struggled with. Main Menu Group Reflection Spend 10 minutes working with your classmates: Help classmates them with corrections they were unable to do alone Ask classmates for support on questions you were unable to correct Main Menu Go Through The Paper Stop me when I reach a question you still have difficulty with. Main Menu Targeted Lesson PREPARE AFTER MARKING THE TEST SHORT LESSON ON SPECIFIC AREAS OF DIFFICULTY Main Menu
