Subject knowledge Matter - download 3 This document can be freely copied and amended if used for educational purposes. It must not be used for commercial gain. The author(s) and web source must be acknowledged whether used as it stands or whether adapted in any way. <Download k3.1_2.1a Matter and Recycling> Authored by Keith Ross, University of Gloucestershire. Accessed from http://www.ase.org.uk/scitutors/date created April 2006 Matter and the re-cycling of materials
Matter and recycling Keith Ross
What happens to (a) the material(b) the atomswhen things are thrown away, burnt, etc? • Rocks - glass, sand ... • Metals - aluminium, batteries ... • Materials from Life - sewage, paper, ... • Plastics - bottles, bags, packaging ... • Volatiles - exhaust gases, insecticides .. • Ionic - corroded metals, fertiliser run-off ...
Matter to understand the fate of materials discarded into the environment, we need to know • the range of materials that occur • their atomic make up. • how they might interfere with living things
Six Ideas 1. Atoms are conserved 2. There are 5 types of material 3. All made from the 100 elements of the periodic table 4. Life, rocks and climate all cycle materials 5. Humans do not re-cycling everything 6. The role of life in cycling materials
First idea: Materials are conserved Consider what happens when : • you change the shape of a lump of plasticene • you crush a sugar lump to a powder Will it … get heavier stay the same get lighter
When you add salt to a cup of water • Will the cup • get heavier • stay the same • get lighter (see how children answered this question on next slide)
When you add salt to a cup of water.. Figure 4.7 Graph showing the percentage of survey pupils who conserved mass/weight of sugar when it dissolved (from Holding 1987)
When you pump air into a football • Will the football • get heavier • stay the same • get lighter 30% 50% 20% Let’s see … (% responses are from a group of 100 18-20 year olds who all gained a GCSE pass at grade ‘C’ or better two to four years previously)
When you burn rubbish • Compared to the rubbish, will all the materials produced during burning (smoke, fumes, ash, char ...) • be heavier • be the same • be lighter (% responses are from a group of 100 18-20 year olds who all gained a GCSE pass at grade ‘C’ or better two to four years previously) 10% 30% 60% (burnt up or because now a gas)
The Candle To hold what is What is the burning function of the wick? To slow the rate of burning What is the To burn - it's function of the actual fuel the wax?
When something is dumped on the rubbish tip, goes up the chimney or down the drain, its atoms: (a) may eventually cease to exist (b) may remain harmlessly in the environment (c) may be used by living things to help them grow (d) may remain in the environment and cause pollution
The periodic table shows only elements ref: page 3
2nd Idea: 5 structures only • The Periodic Table is for Elements • About 100 elements make up our entire universe • But what about the billions of compounds created from them? • CDrom “The Structure Triangle”
2nd Idea: 5 structures only Pure substances (whether they are elements or compounds) come in only five basic structures: • metals (eg copper, brass) • rocks(3-D giant molecular structures - eg granite, bricks) • life-polymers (polymeric/fibrous giant molecular structures - eg wood, nylon) • volatile materials (gases, most liquids and volatile solids) • salts (ionic)
3rd Idea: Matter is made of particles. Explains conservation (1st Idea) • Atoms as unchanging particles amid change • Duplo model of unchanging particles called atoms • These atoms form the basis of an understanding of all the changes we see about us.
Indestructible particles Changing a ‘face’ into a ‘car’ using the same particles. Bulk matter changes, but the underlying particles are the same
Animation of melting & burning • Many people think that 'atoms' melt, burn, expand and dissolve, just like the real materials do. • CD-rom animation
Figure 2.1 A watery solution (drawn by a year one B.Ed student) From: Ross Lakin and Callaghan (2000) Teaching Secondary Science London: David Fulton
2nd Idea (again) - the Structure Triangle for elements and compounds • Bonding depends on the arrangement of the electrons on the outside of atoms. • These outer electrons help to 'glue' atoms together. • A study of chemical bonding allows us to account for the five categories of substances established earlier.
4th idea - Natural material cycles • CD-ROM water cycle • carbon cycle • Rock cycle works over geological time
5th Idea: What happens to the substances we discard into our environment? • CD-ROM Industrial cycle • How will rubbish we throw away affect living things? • We need to look at how life works from a chemical point of view.
6th Idea: Carbon - the element of life. • need for functional groups to make and break chains • Duplo model for polymers
Living cells make enzymes • if a cell can make an enzyme, it can perform a specific reaction. • enzymes are polymerised amino acids 'folded up' in a specific 3-D shape. • this shape allows them to act on just one sort of molecule. • DNA, the genetic code, has the blueprints for making all enzymes
Life builds up and breaks down structures • builds up: protein, DNA, fats, cellulose, starch, etc and digests them (all using enzymes) • the petrochemical industry also makes and breaks substances like nylon, polythene, insecticides, etc • so why is it that only life structures are biodegradable?
Non-Biodegradable materials • Without an enzyme, carbon compounds can only be broken apart by: • ... high temperatures and, • ... (sometimes) bright sunlight. • life has not (yet) evolved to produce enzymes which can break up manufactured organic compounds
Other discarded materials • Consider each of the five substance types in turn: • What happens to them, and their constituent atoms when discarded? • If life cannot use the material we must develop our own (re-)cycles for them. • MM a load of rubbish
Coursework – ideas for concept map Unchanging atoms Made from Types of material Periodic table of elements Structure triangle Natural cycles Life processes