8_3_Metals

=Metals=

CONTEXTUAL OUTLINE: The cultural development of humans has been closely connected with their discovery of materials and invention of tools to the point where major advances in cultural achievement have been described in terms of the materials they learned to use. This has included their use of metals and discoveries of increasingly sophisticated methods of extraction of metals from their ores. Because metals make up the majority of elements, an examination of the physical and chemical properties of metals is also an appropriate context in which to consider the organisation of the common Periodic Table. The development of a Periodic Table represented a breakthrough in the systematic organisation and study of chemistry and enabled scientists to predict the discovery of further elements.


 * // Analyse information to relate the chronology of the Bronze Age, the Iron Age and the modern era and possible future developments //

Outline and examine some uses of different metals through history, including contemporary uses, as uncombined metals or as alloys

Describe the use of common alloys including steel, brass and solder and explain how these relate to their properties

// Gather, process, analyse and present information from secondary sources on the range of alloys produced and the reasons for the production and use of these alloys //

Identify why there are more metals available for people to use now than there were 200 years ago Explain why energy input is necessary to extract a metal from its ore ||  || Given three (3) starter references (with correct bibliographic details included, as a model), definitions of verbs and a scaffold, students will use these sources and at least one other to:
 * Define the term – alloy
 * Outline the properties and uses of at least 3 different metals through history – giving examples of its uses as both a pure element and as an alloy
 * Explain why the Bronze Age came before the Iron Age
 * Explain why some metals have not been discovered or used until recent times
 * Develop a timeline for the discovery and use of different metals and alloys, including examples from both ancient times and more recent times
 * Identify the source(s) used to answer each of the questions
 * Discuss how useful each of the sources was to complete the above tasks
 * Write correct bibliographic details of extra sources used
 * (Worksheet 1, T1 pg 106-115) **
 * (Skills – 12.3b, 12.4d, 13.1c, 13.1f, 14.1g) **

2 Lessons || Completed the work sheet related to the definition of terms
 * (teacher marked) ** ||
 * Focus 2 . ** Metals differ in their reactivity with other chemicals and this influences their uses ** ||
 * // Perform a first-hand investigation and/or process information from secondary sources to determine the metal activity series //

Describe observable changes when metals react with dilute acid, water and oxygen

Describe and justify the criteria used to place metals into an order of activity based on their ease of reaction with oxygen, water and dilute acids

Identify the reaction of metals with acids as requiring the transfer of electrons

// Construct half equations to represent the electron transfer reactions occurring when metals dissolve in hydrochloric and dilute sulfuric acids //

// Construct word and balanced formulae equations for the reaction of metals with water, oxygen, dilute acid // ||  || Recalling that one of the properties of metals is their lustre, and using the following metals: Ca, Zn, Mg, Cu, Fe – observations of the metals are undertaken to determine whether they were reactive with air (oxygen). Then reactions were conducted between the metals and: During the investigation: Using the results of the first-hand investigation, the metals are placed into an activity series.
 * Water
 * 2 molL-1 HCl
 * Introduce the terms “dependent” and “independent” variable where the metal is the independent variable and the degree of bubbling is the dependent variable
 * Dispose of the chemicals appropriately.
 * Conduct risk assessments (especially if a Teacher Demonstration of Na is used )
 * [Skills – 11.2a 11.3b, 12.1c, 14.1a] **


 * 1.5 Lessons **

Using results of the first-hand investigation for reactions between acids and metals, the teacher will model writing the following for the reaction between magnesium and hydrochloric acid:
 * Word equations
 * Balanced formulae equations
 * Complete ionic equations
 * Net ionic equations
 * Half reactions, indicating electron transfer

Students then write these equations for other examples, e.g. 1 Lesson ||   ||
 * Zn + HCl
 * Fe + H2SO4
 * Cu + H2SO4
 * [Skills – 13.1d] **
 * Identify the importance of first ionisation energy in determining the relative reactivity of metals

Outline the relationship between the relative activities of metals and their positions on the Periodic Table ||  || Use the supplied source to extract the first ionisation energies for the Period 3 elements. Follow the instructions to create a data table in EXCEL of:
 * Symbol in Column A
 * Atomic number in Column B
 * First Ionisation Energy (MJ/mol) in Column C

Use the EXCEL to create a scatter graph of the above data, including a curve of best fit for the data. Right-click the relevant part of the graph to re-format it, especially scale used and gridlines. (Handout – creating a table and graph using excel) Repeat the process for the First Ionisation Energies for Group I of the Periodic Table. Define the terms
 * [Skills – 11.1e, 12.3c, 12.4c, 13.1f, 13.1g, 14.1a] **
 * Ionisation energy
 * First ionisation energy

Use these definitions to try to explain the trends in their graphs and relate the activities of the metals to their positions in the Periodic Table.
 * [Skills – 14.1c, 14.1g] **


 * 2 Lessons ** ||  ||
 * * Outline examples of the selection of metals for different purposes based on their reactivity with a particular emphasis on current developments in the use of metals ||  || Use the supplied source to relate the uses of metals and alloys to their properties and reactivities.

0.5 Lesson ||  ||
 * Focus 3. ** As metals and other elements were discovered, scientists recognised that patterns in their physical and chemical properties could be used to organise the elements into a Periodic Table ** ||
 * Identify an appropriate model that has been developed to describe atomic structure

Outline the history of the development of the Periodic Table including its origins, the original data used to construct it and the predictions made after its construction

// Process information from secondary sources to develop a Periodic Table by recognising patterns and trends in the properties of elements and use available evidence to predict the characteristics of unknown elements both in groups and across periods // .
 * ||  || Preview, using Powerpoint, the contribution of the following Scientists to our understanding of grouping elements.
 * Lavoisier – first table of elements
 * Dobereiner – triads
 * Newlands – law of octaves

Students use a data sheet containing the following information for the 68 elements known in 1869 when Mendeleev developed his Periodic Table:
 * Atomic weight
 * Density
 * Atomic volume
 * Hydrogen compound
 * Class
 * Melting point

To construct a periodic table Part 1 – Physical Properties Part 2 – Chemical Properties Part 3 – A Periodic Table Part 4 – Predicting with the Table Part 5 – Extending the Table (extension activity)
 * [Skills – 12.4c, 14.3c] **

Use the results of this activity to discuss the contribution of Mendeleev to our understanding of the properties and placement of elements in the Periodic Table, especially in predicting the properties of elements yet to be discovered.
 * [ **** Skill – 14.1e, 14.3b] **


 * 2 Lessons ** ||  ||
 * Explain the relationship between the position of elements in the Periodic Table, and:
 * electrical conductivity
 * hardness
 * ionisation energy
 * atomic radius
 * melting point
 * boiling point
 * combining power (valency)
 * electronegativity
 * reactivity ||  || For each of the properties below, use the supplied sources to identify the trends across a period and down a group then explain the trends in terms of the structure of the elements.
 * electrical conductivity
 * hardness
 * ionisation energy
 * atomic radius
 * melting point
 * boiling point
 * combining power (valency)
 * electronegativity
 * reactivity
 * [Skills – 14.1a, 14.1c, 14.1g] **


 * 2 Lessons ** ||  ||
 * Focus 4. ** For efficient resource use, industrial chemical reactions must use measured amounts of each reactant ** ||
 * Define the mole as the number of atoms in exactly 12g of carbon-12 (Avogadro’s number)

// Solve problems and analyse information from secondary sources to perform calculations involving Avogadro’s number, number of moles present in reactants and products using: //

||  || * Define the mole as a number, a VERY LARGE number – 6.022 x 1023 > Comparison 1: Comparison 2: Identify relevant information in the question; identify what needs to be “found”; identify the number of significant figures required in the answer; identify the appropriate equation to use to answer the problem; and perform the appropriate calculation for each of the following types of questions:
 * Compare language using two examples – one familiar (using dozen), one unfamiliar (using mole). Draw out the process used to answer the question about the eggs, then apply the same process to the example about the sodium atoms.
 * o There are 12 eggs in one dozen eggs. How many eggs are there in ½ dozen?
 * o There are 6.022 x 1023 sodium atoms in one mole sodium atoms. How many sodium atoms are there in ½ mole?
 * o One dozen eggs has a mass of 700 g. What is the mass of ½ dozen eggs?
 * o One mole of sodium atoms has a mass of 22.99 g. What is the mass of ½ mole sodium atoms?
 * o Mass → Mole
 * o Mole → Mass
 * o No. of particles → Mole
 * o Mole → No. of particles
 * o Mass → No. of particles
 * o No. of particles → Mass
 * [Skills – 11.1c, 11.1d, 12.4b, 14.2a, 14.2b, 14.1f, 14.1h] **

4 lessons ||  ||
 * ||  || Solve problems using first-hand investigations, then outline the method used and measure out specific quantities of particular chemicals, so they can visualise the quantity, then perform appropriate mole calculations, e.g. determine the number of atoms present in a level teaspoon of sulfur powder.

**[Skills – 11.1c, 11.1d, 11.2d, 12.2b, 12.4a, 14.2a, 14.2b, 14.2d, 14.1f, 14.1h]**
 * 1 Lesson ** ||  ||
 * Distinguish between empirical formulae and molecular formulae ||  || Following a teacher-led discussion, recognise that chemists are not usually given the chemical formulae of compounds present in substances, rather they are given % composition data from which they have to determine the formula and hence identify the compounds present.

Define the terms:
 * Empirical formula
 * Molecular formula

Use % composition data and their understanding of mole ratios to determine the empirical formula of compounds. Where the molar mass of a compound is given, also determine its molecular formula.
 * [Skills – 11.1c, 11.1d, 14.2a, 14.2b, 14.1f, 14.1h] **
 * 1 Lesson ** ||  ||
 * // Process information from secondary sources to interpret balanced chemical equations in terms of mole ratios //

// Perform a first-hand investigation to measure and identify the mass ratios of metal to non-metal(s) in a common compound and calculate its empirical formula // Compare mass changes in samples of metals when they combine with oxygen ||  || Change word problems into balanced chemical equations, then determine mole relationships from the equations.
 * [Skills – 12.4b, 12.4d] **

Follow the procedure provided to determine the formula of the compound formed when magnesium reacts with oxygen by measuring masses until there is a constant mass. Once masses of magnesium and oxygen are known, calculations are performed to determine the empirical formula for this compound. Hot equipment must be handled safely and allowed to cool before weighing. 2 Lessons ||  ||
 * [Skills – 11.1b, 12.1d, 12.4b, 14.1f] **
 * // Process information from secondary sources to investigate the relationship between the volumes of gases involved in reactions involving a metal and relate this to an understanding of the mole //

Recount Avogadro’s Law and describe its importance in developing the mole concept

Describe the contribution of Gay Lussac to the understanding of gaseous reactions and relate this to an understanding of the mole concept ||  || Following a class discussion that draws out the relationship between moles, molecules and volumes of gases at constant temperatures and pressures, calculations are performed to assess their understanding of these concepts.

2 Lessons ||  || // Discuss the importance of predicting yield in the identification, mining and extraction of commercial ore deposits // Explain why ores are non-renewable resources
 * Focus 5. ** The relative abundance and ease of extraction of metals influences their value and breadth of use in the community ** ||
 * Define the terms mineral and ore with reference to economic and non-economic deposits of natural resources

Recount the steps taken to recycle a named metal such as aluminium ||  || Use textbook to define the terms:
 * Mineral
 * Ore
 * Economic deposit
 * Non-economic deposit
 * Natural resource
 * [Skill – 12.3b] **

Following a class discussion and using textbook, create notes to explain that ores are non-renewable resources and why it is important to have accurate information regarding yield when extracting commercial ore deposits.
 * [Skill – 12.3b] **

Using the textbook as a source, convert a written text to a diagrammatic text to indicate the steps taken to recycle aluminium.
 * [Skills – 12.3b, 13.1e] **
 * 1 lesson ** ||  ||
 * Describe the relationship between the commercial prices of common metals, their actual abundances and relative costs of production

// Analyse information to compare the cost and energy expenditure involved in the extraction of aluminium from its ore and the recycling of aluminium // // Justify the increased recycling of metals in our society and across the world // ||  || Use the internet and / or daily newspapers to identify the price of the following metals:
 * Gold
 * Silver
 * Platinum
 * Copper
 * Zinc
 * Iron
 * [Skill – 12.3b] **

Use the textbook to identify the abundances and methods of extraction for each of the metals indicated above.
 * [ **** Skill – 12.3b] **

Using the gathered information, identify and describe the relationship between the metal’s price, its abundance and its method of extraction.
 * [Skills – 12.4d, 14.1a] **

Using the text as a source, compare the cost and energy expenditure involved in the extraction of aluminium from its ore and the recycling of aluminium. Using this information and previous information about limited resources, justify the increased need for recycling of metals in society. 3 Lessons ||  ||
 * [Skills 12.3b, 14.1a, 14.1h, 16c] **