Lesson video

Welcome to today's lesson on common elements.

It's part of the Atoms, Elements and Compounds topic.

My name's Mrs. Mytum-Smithson.

I'm pleased that you've come along to learn with me today.

Don't worry if you don't know anything about elements.

We're going to look at some common elements that are used in everyday life, and the hazards associated with those.

By the end of today's lesson, you should be able to communicate clearly some properties, uses and dangers of some common elements.

The keywords for today are hazard and metalloid.

On the next slide, there's some definitions of them.

You can pause the slide and read them if you wish.

Today's lesson consists of three learning cycles.

Firstly, we're gonna learn about hazard symbols, then we're gonna look at some uses of common elements, and then finally we're going to get onto that last learning cycle of metalloids.

So hazard symbols is the first learning cycle.

Let's get going.

Substances can be hazardous in different ways.

This just means that they can be dangerous in different ways.

So we're going to look at these hazard symbols, and these are used to tell us in what way or how a substance is dangerous.

Here's some very common ones that you might have seen on cleaning products, or perhaps on the back of a vehicle.

We're gonna have a look at each one of these in more detail in the next part of the lesson.

This symbol means corrosive.

If you have a look, you've got what looks like a hand with some liquid being dropped on it, or a surface, perhaps a table with some liquid being dropped on it, and some part of that surface or that hand has now gone missing.

So this image shows what might happen if you spill a corrosive substance, for example acid, on your hand or on a table.

It might damage your skin or the material that it touches.

You may frequently see this on the back of cleaning products.

This symbol is corrosive.

We're going to use symbols 'cause they're really useful, and the symbols that are useful because they allow anybody, no matter whether they can read, or whatever language they speak, to communicate hazards to each other.

So you can pick up something that's got a hazard on, by looking at that symbol, you can tell that it's dangerous in some way.

So they're also easy to see on a bottle, so very clear.

So you know that when you're buying something, what hazards are associated with it.

This is the moderate hazard symbol.

So a moderate hazard symbol means that the substance might irritate.

So it's not gonna dissolve the skin necessarily.

It's not gonna burn a big hole in your skin.

But it definitely should be kept away from eyes and the skin.

Here it is on the back of a dishwasher cleaner.

You can see there it says warning underneath it.

And this is a moderate hazard symbol.

Some substances have got more than one hazard associated with them.

This kind of waterproof spray has got three hazards on the back, so this is used on waterproof trainers.

It's a moderate hazard.

We can see there with that exclamation mark that we looked at in the previous slide.

It's flammable and can set on fire when exposed to heat or sparks.

So this is flammable, it looks like a flame.

And we've got environmental hazard.

This means it contains substances that are toxic to plants and animals.

So you can see like a dead tree and a dead fish.

So this is an environmental hazard.

So this substance has got three different hazards associated with it, so you would clearly want to read the instructions on how to use it safely.

These sparklers have got a small but very clear explosive hazard sign.

So this looks like a circle or a ball being blown up.

This is explosive, and this means that the substance might explode as a result of heat or shock or friction.

This is a substance that shows that the symbol may have short or long-term health effects.

So this is a health hazard.

So if you have a look, looks like a person with their kind of insides dissolving, being exploded inside.

Certainly not pleasant, and you should be careful for substances that show this, because they may cause short or long-term health effects.

So this is health hazard.

Then we've got another one which is oxidising.

So this looks very familiar to the flammable one because it shows that this substance might burn even without air.

It should be kept away from anything that could set it alight.

This is oxidising.

Anything that's got the gas under pressure warning label, this is warning you that the gas could explode when heated.

So here it is on the back of an ambulance because they have gases that are under pressure inside of the ambulance to help you breathe.

And this is the label that must be on the back of their ambulance.

This is gas under pressure.

This is toxic, so skull and cross bones.

This warms that the substance could cause death if swallowed or inhaled.

So if you breathe it in or you swallow it, it might cause death.

That's why it's got that skull and cross bones on to remind you that it's very hazardous.

Now a check for understanding.

Which symbol represents a health hazard? Is it A, B or C? Pause the video for some thinking time.

Press play when you've got your answer.

Well done if you said C.

That represents a short or a long-term health hazard, not very nice at all.

What hazard symbols are on this oven cleaner? So have a look at the hazard symbols on the oven cleaner.

Which ones are they? Explosive and corrosive, flammable and corrosive, flammable and gas under pressure.

Pause the video for some thinking time.

Press play when you're ready for the answer.

Well done if you said flammable and corrosive.

You've got those right.

Remember, flammable is that flame sign, and then the corrosive is the hand and the surface being corroded by the liquid that's being poured on them.

Well done if you got that right.

Quick check now, a true or false.

Symbols are used because it allows people of any language to communicate hazards to each other.

Is that statement true or is that statement false? Pause the video if you need thinking time.

Press play when you've got your answer.

Well done if you thought it was true.

Symbols are used because it allows people of any language to communicate hazards to each other.

We've got a justify your answer now.

We've got two statements here.

Statement A, it's important that everyone can understand the hazards.

Statement B, only science teachers need to know about hazards.

Pause the video for some thinking time and press play when you've got your answer.

Well done if you said it is important that everyone can understand the hazards.

So it's really important that everybody, not just science teachers, know about hazards.

Well done if you got that correct.

Now we're moving on to our task.

The first part is going to be matching up symbols, names and definitions.

So here's the symbols, here's the names, and here's the definitions, so here's the descriptions about what they are.

I want you to match the symbol to the name and definition.

For example, here we've got something that's flammable, that tells you it may catch fire when heated.

So the first one's done for you, you've just got to complete the other four.

Pause the video, complete the activity, press play when you've got the answers.

Well done for completing the task.

Here's the feedback.

So this first one here is a health hazard that may cause short or long-term health effects.

The next one there looks like that ball is exploding because that represents something that's explosive.

So it may explode as a result of heat, shock or friction.

Next one is corrosive.

That may cause damage to skin and materials.

And finally, the one that is an environmental hazard, so that it's toxic to plants and animals.

For part two of task A, what I want you to do now is help Izzy to correct her ideas.

She needs to name and describe all three of the hazard symbols shown.

So Izzy says, "I think that the toxic symbol is the one that looks like an exclamation mark.

It shows that the substance is only a little bit dangerous.

You might see it on a bottle of compressed air." Obviously she's got some incorrect ideas, you need to correct them.

Her friends have got some correct information to help her.

So Jacob said, "This is a symbol for gas under pressure." And Alex is saying, "This is a symbol for something that is very dangerous." Pause the video now and then press play when you've got the answers.

Well done for working hard and completing that task.

It might not have been straightforward, but I'm sure you've given it a really good go.

So Izzy said, "The toxic symbol is the one that looks like a skull and cross bones.

It shows that a substance can cause death if swallowed or inhaled." This is a symbol for gas under pressure, so you might see this symbol on a bottle of compressed air, for example, the ones that divers use.

This is a symbol for a moderate hazard and the substance may irritate the skin or eyes, so you still need to keep it away from them.

But anything that's got this symbol, this exclamation symbol is not as dangerous as the one that's got the toxic symbol on it.

Well done if you've got all those three statements correct.

Now we're moving on to our second learning cycle, uses of common elements.

So mercury is a really unusual metallic element.

You might have come across it.

It's liquid at room temperature.

So there's only two elements that's liquid at room temperature, mercury is one of them.

It's very, very dense, which means it's very, very heavy for its volume.

It's got a melting point of minus 39 degrees C, so that's pretty low for an element.

And it expands a lot when it's heated.

This means that we can use it in thermometers, however mercury can conduct electricity and heat, but it is an environmental hazard.

It's toxic and it's a health hazard.

So this is pretty nasty stuff, and this is why we don't tend to use mercury thermometers any longer in schools.

Copper's a metallic element.

It's non-hazardous as a pure metal.

It's fairly unreactive.

It's malleable, which means if you bend it, it will keep its shape.

And these properties are why it's used to coat 1p and 2p coins.

It's used in cooking pans, pipes and electrical wires.

So obviously food's in contact with the pans, and the water's in contact with pipes.

Here, the top picture shows some pans and the bottom picture shows some water pipes.

And it's fairly unreactive, so this is non-hazardous.

There are no hazard warning labels that are needed to put on these.

Quick check for understanding.

Copper can be bent into shape.

What property means an element can be bent into shape? Is it shiny? Is it malleable? Is it melting point or is it conducts heat? Pause the video for thinking time.

Press play when you've got your answer.

Well done if you said malleable.

Malleable means that an element can be bent into shape.

Neon is a non-metal.

It's a gas at room temperature.

It's very unreactive.

However, it's got a unique property that when you pass an electric current through it, it glows red/orangey colour.

So this open sign is made with a glass tube, and that glass tube has been bent into shape to say the word "Open." It's been filled with gas, and an electric current is passing through it.

When we're storing neon, we would store it under pressure, so you would need to have the hazard warning symbol gases under pressure.

So these properties are why it's used in neon lightings and signs.

Many non-metals are gases at room temperatures, for example helium.

What can be said about their boiling points? Are they generally very high, generally very low, or is the state of matter at room temperature no indication of boiling point? Pause the video for a think, then press play when you've got your answer.

Well done if you said they're generally very low, for example, less than zero degrees C.

Let's have a look at nitrogen.

So nitrogen is a non-metal.

It's very unreactive.

It's the highest percentage of gas in the air, so it takes up 78% of the air is made of nitrogen.

It's a gas at room temperature.

And it's able to condense at a very low temperature.

So at minus 196 degrees C, it changes from a gas into a liquid.

And this gives its unique properties.

So it's used to fill up things like crisp packets to keep food for fresher and longer, because it's unreactive.

And also it's very, very cold, so it can be used to freeze biological samples.

Also, it can be used to freeze ice-cream.

So true or false, all elements are a gas or a solid at room temperature? Is that true or is that false? Pause the video and have a think.

Press play when you've got your answer.

Well done if you said that that was false.

All elements are not a gas or a solid at room temperature.

We need to justify your answer.

Nitrogen is always a gas, or mercury is a liquid at room temperature.

Which one of those statements justifies the true or false statement? Well done if you said that mercury is a liquid at room temperature.

There are two elements that are liquid at room temperature, one of them is mercury.

Now I've got a task for you, so you can practise your knowledge.

Are these statements true? So you've got three statements, and you're going to say if you are sure that they're correct, you think it's correct, you think it's incorrect, or you're sure it's incorrect.

So statement A, all elements have the same properties.

Statement B, malleable means that an element can be melted.

Statement C, non-metals have a low melting and boiling point.

Pause the video now, write your answers, and then press play when you've completed the task.

Well done for completing that part of the task.

Let's give you some feedback.

So all elements have got the same properties, that is incorrect.

All elements have got unique properties, so ways that they behave that is unique to their element.

Malleable means that an element can be melted.

That is also incorrect.

Malleable means that it can be bent into shape.

Non-metals have very low melting points.

That is correct.

Most non-metals are gases at room temperature.

Well done if you got all those three correct.

Now we're gonna have a go at task B, part two.

Copper is used for making pans.

What I want you to do is sort the properties of copper into the table to explain why pans are made of copper.

So you've got three columns.

One column, if it's got that property and it's needed to be a pan, then you're gonna put it in that one.

If it has the property but it's not needed for a pan, you are then gonna put it in the middle column.

And if it does not have the property, you're going to put it in that final right hand column.

So here's the properties that you're going to need to sort.

Low melting point, high melting point, electrical conductor, electrical insulator.

So that means it won't conduct electricity.

Dull and shiny, malleable and brittle, thermal insulator and thermal conductor.

So thermal insulator will not conduct heat.

A thermal conductor will conduct heat.

Pause the video, sort the statements, and press play when you're ready for the answers.

Well done for completing that task.

Let's have a look at the answers now.

So a property needed for a pan, needs to have a high melting point.

We wouldn't want the pan to melt on the stove.

It needs to be malleable, so we need to bend it into a pan shape.

Thermal conductor, it needs to conduct heat from the hob all the way through to the food.

Electrical conductor.

So copper does conduct electricity, but we don't need it to conduct electricity to be a pan.

This last one here is shiny.

So I put this in both columns.

Property needed for a pan, or has property but not needed for a pan.

It depends on whether you want a pan to be shiny or not, so it appears in both of them.

It does not have the property.

So copper does not have a low melting point, it is not brittle, it is not a thermal insulator, it's not electrical insulator and it's not dull.

So well done if you've got all those correct.

Part three now of task B.

What I want you to do here is I want you to match up the property to the use, and then suggest which element it could be.

So we've got three columns.

Column one is property, so malleable and good thermal conductor.

Glows when a current is passed through it at low pressure.

Unreactive gas at room temperature.

Liquid at room temperature, which can expand when heated.

And then we've got use, a pan, fill a thermometer, advertising sign, or in food packaging to keep fresh.

And the elements are, what element do you think it is, mercury, copper, nitrogen or neon? So pause the video now, match up the properties to the uses, and suggest which element it is, then press play when you're ready for the answers.

Well done for completing that task.

Let's go through the answers now.

So a malleable and good thermal conductor, a pan could be made of copper.

Glows when a current is passed through at low pressure, that's gonna be used in an advertising sign, and that could be neon.

Unreactive gas at room temperature used in food packaging to keep food fresh, and that's nitrogen.

Liquid at room temperature, which can expand when heated, that's gonna fill a thermometer and that's gonna be mercury.

So well done if you've got all of those correct.

Now we're going to move on to our final learning cycle of the lesson, metalloids.

Probably not heard of that word before, so let's get on and learn about it.

Some elements have got properties of both a metal and a non-metal and they're called metalloids.

Metalloids are found on the periodic table between the metal elements and the non-metal elements.

So if we have a look here, you can see we've shaded in the metalloids in this pale green colour.

You can see on the right hand side, we've got the non-metals, on the left hand side, we've got the metals, and in the middle there, we've got the metalloids.

Here's what some of the metalloid elements look like.

So we've got tellurium, germanium, and silicon.

Each metalloid element has its own unique properties, some of which will be like metals, so for example shiny, and some will be like non-metals, for example they're gonna be brittle.

So we've got a picture of arsenic there.

You can see it's shiny like a metal and it's also brittle.

Here's a table that compares the properties of metalloids to those of metal and non-metal.

So the state at room temperature, metals are usually solid, apart from mercury, which is an exception.

Metalloids are solid and non-metals are either a solid, a liquid, or a gas, mainly a gas.

Melting point, high for a metal, high for a metalloid, low for a non-metal.

Is it shiny or is it dull? So for a metal and a metalloid, it's shiny, and for non-metal, it's dull.

Electrical conductivity.

So this is an interesting one.

For a metal, all metals conduct electricity well.

For metalloids, we've got poor and good, so poor at low temperature, but they can conduct at high temperature.

Non-metals, poor, except for graphite, which is an exception.

Malleable and brittle, so metal is malleable, means we can bend it into shape.

Metalloid and non-metals are brittle.

So you can see from this that metalloids really do share some of their properties with metals and some of their properties with non-metals.

A quick check for understanding now.

Which element could be a metalloid? So have a look at the pictures and think, which of one of these could be a metalloid? Is it A, B, or C? Pause the video for some thinking time and press play when you've got an answer.

So which element could be a metalloid, is it A, B or C? Well, metalloids are shiny, so it could be A or it could be C.

But it is C because A has been bent into shape, which means that A is malleable, but C is a metalloid, 'cause metalloids are not malleable.

Well done if you've got that one right.

A quick check for understanding here.

Metals conduct electricity the best.

Most non-metals do not conduct electricity.

Metalloids can conduct electricity better than metals and non-metals, better than non-metals but not as well as metals, or not as well as metals or non-metals.

Pause the video, give me an answer, and press play when you've got that answer.

Well done if you said better than non-metals but not as well as metals.

They kind of fit in between the properties there of a non-metal and a metal, they're metalloids.

Quick check for understanding here.

Metalloids are brittle like non-metals.

Is that true or is that false? Pause the video if you need thinking time and press play when you've got an answer.

Well done if you said that that is true, metalloids are brittle like non-metals.

And justify your answer.

Metalloids have the same properties as non-metals.

Metalloids have some properties that are the same as non-metals.

Pause for some thinking time and press play when you've got your answer.

Well done if you said B, metalloids have some properties the same as non-metals.

This is task C.

It looks a little bit tricky, but if you go through it step by step, you'll be absolutely fine.

Look at the data to decide if the element is a metal, non-metal or metalloid.

So you're gonna have a look at element A, and then you're gonna have a look down that column, tell me is it a metal, a non-metal or a metalloid? Pause the video now and then press play when you've got your answers.

Well done for completing that task.

I hope you found it quite straightforward to do.

So we'll look at element A.

It's a solid room temperature.

It's got a high melting point.

It's shiny, conducts electricity well, and it's malleable, so that makes it a metal.

Element B is solid at room temperature, it's got a high melting point, it's shiny, it doesn't conduct electricity well and it's brittle.

Okay, so those last couple ones should mean that you know that it is a metalloid.

So element C, it's solid at room temperature, it's got a high melting point, it's shiny, it conducts electricity well and it's malleable.

That means it is a metal.

So it's got just the same properties as A, which makes it a metal.

Let's have a look at D now.

So it's a gas at room temperature.

It's got a low melting point, it's dull, it's poor electrical conductivity and it's brittle.

That means that it is a non-metal.

And E is a solid.

It's got a high melting point, it's shiny, it's got good electrical conductivity, however it is brittle.

So that last bit there where it says it's brittle, that's gonna give you the information that you need to see that it is a metalloid.

So well done if you got all of these answers correct.

You've done really well.

Here's a summary of today's lesson on common elements.

Hazard symbols are used to describe dangers of substances.

Each element has its own distinct properties.

Metalloid elements have some properties of metals and some properties of non-metals.

Well done for working really hard this lesson.

I'm sure that you've learned loads and are now an expert on elements.