2.2. Bases teóricas – científicas
2.2.1. Hábitos de higiene en el hogar
The outline learning plan has been included in this unit as guidance and can be used in conjunction with the programme of suggested assignments.
The outline learning plan demonstrates one way in planning the delivery and assessment of this unit.
Topic and suggested assignments/activities and/assessment Introduction and safety briefing
Formal teaching of periodic table, elements, mixtures and compounds
Theory and practical work for Assignment 1: Elements, Mixtures and Compounds (P1, M1, D1)
Practical work on the physical properties of elements, mixtures and compounds including conductivity, boiling and melting points and state of matter
Theory and practical work for Assignment 2: How Physical Properties of Substances Determine Their Uses (P2, M2)
Formal teaching of atomic structure and trends in the periodic table
Practical work on the trends in the periodic table including reactivity of the alkali metals and halides
Theory and practical work for Assignment 3: Electronic Structure and the Periodic Table (P3, P4, M3, M4, D2) Formal teaching of rates of reaction
Practical work on rates of reaction looking at temperature, particle size, concentration and catalysts Assignment 4: Controlling Industrial Reactions (P5, M5, D3)
Formal teaching of the ways the Earth can be affected by man and natural phenomena covering tectonic plates, volcanoes, burning of fossil fuels and the extractive industries
Practical work on the way man has changed the environment including acid rain on rocks and the production of gases in combustion
Assignment 5: Affecting the Environment (P6, P7, M6, M7, D4)
Assessment
The assessment strategies used in this unit need to reflect the evidence required to address the grading criteria and should be assessed through scientific investigative assignments. It is important that learners’
communication skills be assessed through presentations, scientific laboratory reports, posters, graphs, charts etc.
For P1, learners must identify if a substance is an element, mixture or compound from its name and from a knowledge of common substances, eg sea water. To achieve M1, learners will need to describe the differences between elements, mixtures and compounds. This could include drawing or recognising diagrammatic representations of elements, mixtures and compounds. To achieve D1, learners could be asked to explain the differences between elements, mixtures and compounds in relation to, say four, specific examples. Learners could explain how to show whether air is a mixture or a compound, how to show that iron sulphide is a compound and not just a mixture of iron and sulphur. This could be assessed by preparing a poster which uses examples to explain the differences between elements, mixtures and compounds.
To achieve P2, learners could investigate, for example, the physical properties of substances related to an industry (eg construction) or a use (eg a mobile phone). Learners could carry out simple comparisons of data for thermal or electrical conductivity, melting point or boiling point and solubilities. They could identify trends in the data and make predictions for chemicals with similar physical properties. Learners could also be given the boiling points of different chemicals and predict their state at room temperature and pressure, eg the separate fractions obtained from the fractional distillation of crude oil. To achieve P2, the learners would have to relate the uses of the chemicals to their physical properties. At least three chemicals should be studied. The tutor will have to select the substances carefully so that the unit is delivered efficiently in terms of time. The examples should be straightforward. To achieve M2, learners would have to explain the uses of the chemicals in terms of their physical properties. The scope of D2 should be limited to three chemicals, chosen by the tutor to reflect the interests of the learners or local industry. Uses are to be in relation to physical properties.
To achieve P3, learners could either complete tables, create posters, visual presentations or cards which describe the atomic structure of the first twenty elements. There should at least two examples of isotopes of elements included. Learners could be given the structures of some of the elements 1 to 20 and asked to work out the structures of some of the other elements from 1 to 20. To achieve M3, the relationship between the position of the group in the periodic table and the number of electrons in the outer shell should be established. The addition of another shell of electrons on moving from lithium to sodium to potassium to rubidium, and from fluorine to chlorine to bromine to iodine should be described. Learners should be able to explain the differences in reactivity of the alkali metals and of the halogens to their electronic structures in order to achieve D3.
To achieve P4, learners should investigate the different chemical properties of the group 1 and 7 elements, such as how they react with water and air and place the elements in their order of reactivity within the groups. For group 1 elements this could also include a consideration of how they are stored and that they form alkaline compounds when they react with water. For group 7 elements their ability to form acidic compounds when they react with water.
To achieve P5, learners should investigate the effects of concentration, particle size, temperature and presence of a catalyst on the rates of chemical reactions and show that, for example, increasing temperature increases the rate of reaction. This should involve at least one instance of collection of concentration data as a function of time. To achieve M5, learners should explain how changing the rates of reactions affects certain industrial process. To achieve D3 learners should include an analysis of how different factors affect the yield of an industrial reaction. This should include information on the operating conditions used in industry for different reactions.
To achieve P6, learners should identify the environmental consequences of at least two human activities as outlined in the content and their benefits, drawbacks and risks, that may have ethical implications. To achieve M6, learners will have to describe how humans may exercise choices which could limit or worsen the effects of the environmental damage that they cause. This could be in relation to the two activities, identified in P6.
To achieve D4, learners should explain how the effects of at least two environmentally damaging human activities may reduced. This may be in relation to the activities identified in P6.
To achieve P7, learners should identify at least two natural factors, for example volcanic eruption or movement of tectonic plates and state how these factors have changed the atmosphere and surface of the earth. This could be limited to a specific volcanic eruption or a clash of tectonic plates. M7 requires more description and requires the learners to consider the effects of several events like those discussed in P7 which have happened over millions of years.
Programme of suggested assignments
The table below shows a programme of suggested assignments that cover the pass, merit and distinction criteria in the assessment and grading grid. This is for guidance and it is recommended that centres either write their own assignments or adapt any Edexcel assignments to meet local needs and resources.
Criteria covered Assignment title Scenario Assessment method P1, M1, D1 Elements, Mixtures and
Compounds You are the education
officer for a large chemical company which has just opened, you have been asked to prepare posters, explaining the difference between elements mixtures and compounds for a ‘meet the neighbours’ open day display.
Prepare a poster which explains the differences between elements, mixtures and compounds.
P2, M2 How Physical Properties
of Substances Determine Their Uses
As part of the open day activities, you will need to present material showing how the physical properties of some of the materials made by your company, determine their uses.
Present the results of an investigation of the physical properties of at least three substances and explain how these properties affect their uses.
P3, P4, M3, M4, D2 Electronic Structure and
the Periodic Table Part of the presentation for the open day is to provide an explanation of the structure of the periodic table in relation to electronic structure and reactivity.
Prepare a table showing the atomic structure, of the first twenty elements.
Relate this to the location of the alkali metals and halogens in the periodic table and the reactivity of these elements.
P5, M5, D3 Controlling Industrial
Reactions As one of the chemists
at a local plant, you have been asked to explain to the people operating the chemical plant, the factors which affect rate, yield and atom economy of reactions.
Carry out experiments and collate data on chemical reactions in order to explain all the factors which make the reaction go faster, maximise yield and optimise atom economy.
P6, M6, D4, P7, M7 Affecting the Environment The editor of the local paper has asked you, as the chemist responsible for the environmental impact of the company’s processes, to respond to an alarmist article written by an environmental pressure group.
Write an article which presents a balanced view of the likely environmental impact or your company and how this may be minimised. The article should also explain the environmental impact of natural events.