matter 1 – download k3.1_2.1aapril 2006slide 1 subject knowledge matter - download 3 matter and...

Matter 1 – download K3.1_2.1a April 2006 slide 1

Subject knowledge Matter - download 3

Matter and the re-cycling of materials

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<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 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 conserved2. There are 5 types of material3. All made from the 100 elements of

the periodic table4. Life, rocks and climate all cycle

materials5. Humans do not re-cycling everything6. 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 heavierstay the sameget lighter


When you add salt to a cup of waterWhen 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..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 footballWhen you pump air into a football

• Will the football

•get heavier•stay the same•get lighter 20%

50%

30%

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 rubbishWhen 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

What is the function of the wax?

To hold what is burning To slow the rate of burning To burn - it's the actual fuel

What is the function of the wick?


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


Types of material

Unchanging atoms

Periodic table of elementsStructure

triangle

Natural cycles

Life processes

Made from

Coursework – ideas for concept map

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