Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
States Of Materials
Solids – a solid is something, which retains its shape.
It can be hard like iron or soft like rubber and fabric, flexible like plastic or stiff like wood, fragile like glass or tough like brick, it can be torn like paper, or remain strong like PVC, it may be malleable (squashable) like Playdoh but it will always keep the last shape you left it in and does not need to be kept in a container.
When the solid is a very small particle like sand or flour, it keeps its shape, but of course, we usually see lots of particles together. When there are lots of these together, they behave like a liquid, and we usually keep them in containers.
Liquids – a liquid does not keep its shape.
It needs a container if it is not to spill over the ground. Gravity helps to keep it at the bottom of the container. Water has to be kept in a pond or tank. If it is the container has a hole, the water will leak out. Milk is delivered in cartons and bottles; otherwise it would leak all over our refrigerators. Washing up liquid is stored in special bottles that you squeeze to help the liquid out at the top.
Gases – a gas needs a container, often with a lid, to keep it in.
Most gases will escape through any opening in a container. The air that we breathe is made up of lots of different ones, such as oxygen, carbon dioxide, and nitrogen. Some gases are very light, such as helium, and we use it to fill special party balloons, because it makes the balloon float.
Gases are invisible and often don't have a smell. Some gases are explosive when a match is brought near, like methane (which we use in our cookers and central heating systems), so a horrible smell is added so that people know when it leaks.
Mercury is an example of a metal in a liquid state.
Using Materials
Materials are the 'stuff' the world is made up of. Materials are all different. Some are strong, or hard, or transparent. Some are weak, or soft, or opaque.
We pick a material to do a job because it will be good at it. Windows would be no good if you couldn't see through them. A chair would be useless if it collapsed when you sat on it. So we choose materials that are right for the job. We may shape or change them. We may even make new materials that will fit the task. We test materials to make sure that they are strong enough, or bendy enough, or absorbent enough, for the job.
Changing Materials
Some materials change when they are mixed, cooled or heated. Sometimes these changes can be reversed, sometimes they cannot. When materials are combined a new material will have been formed.
Most materials we use have been changed in some way. For example clay is a natural material. To change clay permanently – to make a chemical change – we must heat the clay in a hot oven called a kiln.
There are many ways of changing materials. You can melt some, freeze some, dissolve some and even burn some. Some of these changes can be reversed - you can get back what you started with. But some are irreversible. They are permanent. You can never get back what you started with. You have a completely new material.
Most cooking is like that. Once food is cooked, it is changed irreversibly. But making a solution can be reversible. You can often get back what you started with. Some irreversible changes are exciting to watch. Colours change, new materials are produced. There may be bubbling. They may get hot.
Identifying Materials
Look around your house or school. Can you name and write down objects that are made from the following list:
Plastic- Metal
- Wood
- China
- Glass
- Rubber
- Paper
- Cotton
- Polyester
- Wood
- Card
- Perspex
- Leather
- Polystyrene
- There may be materials there you don’t recognise so ‘Ask Albert’ what they are.
Properties Of Materials
You can tell some of the properties of a material by feeling them. They may be smooth, rough, rigid or stiff flexible, hard, soft, see through, opaque (you can’t see through it), strong, weak. Can you think of any more? If you can send them to Albert, he is building up a list.
Believe It Or Not There's No Lead In Pencil Lead!
The centre of the pencil - known as the writing core - is made of a non-toxic mineral called graphite.
Graphite came into widespread in the 16th century, following the discovery of a large graphite deposit in Borrowdale, England. As the story goes, a passer by found bits of shiny, black graphite clinging to the roots of a fallen tree. The whole countryside was abuzz with talk about this mysterious mineral, which soon came to be known as "plumbago" or, more commonly, "Blacklead".
Graphite left a dark mark, making it ideal for use by writers and artists. But it was so soft and brittle that it required a holder. At first, sticks of graphite were wrapped in string. Later, the graphite was inserted into wooden sticks that had been hollowed-out by hand! The wood-cased pencil was born.
Materials observation
Below are some materials. Can you fill in the table or better still make up your own and email it to me albert@sciencebus.co.uk. There’s a prize for the best one!
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Can You See Through It?
(Is It Transparent?) |
Is It Strong?
(It Won’t Break Easily) |
Is it hard?
Will It Scratch? |
Is It Flexible?
(Bendy) |
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| Glass |
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| Table |
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| Mug |
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| Plastic Bag |
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| Knife |
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Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
