Lead - Periodic Table of Videos

Summary

This script explores the unique properties of lead, from its softness and reactivity to its historical uses and modern applications. It delves into lead's role in early paint and its unfortunate effects when combined with air pollutants, its use in World War II submarine camouflage, and its effectiveness in shielding against radioactive particles. The script also touches on the heavy metal's presence in Roman times, its use in water pipes, and its once widespread addition to petrol, highlighting the shift to lead-free alternatives due to health concerns.

Takeaways

• 🔩 Lead is a soft and highly moldable metal, which makes it suitable for various applications including old lab equipment for holding strong acids.
• 📦 Lead's reactivity is quite low, which is why it was historically used for storage vessels in laboratories.
• 🎨 Lead oxide, which has a white color, was historically used in paints, but it would eventually turn grey or black due to a reaction with sulfur in the air.
• 👷‍♂️ In the past, the color-changing property of lead oxide was utilized for military purposes, such as camouflaging submarines by reacting lead oxide with sulfur to change its color.
• 🛠️ Lead's atomic weight makes it an effective shield against radioactive particles, especially alpha and beta particles, which is why it's used in bricks for radiation protection.
• 🧱 Lead bricks are designed with grooves and points to ensure a tight fit when stacked, preventing any radioactive particles from passing through gaps.
• 🔬 For experiments requiring visibility, lead glass is used, which allows scientists to see inside containers while still providing protection against radiation.
• 🍷 Historically, lead was used in wine by the Romans to sweeten it, which may have contributed to health issues and even the fall of the Roman Empire.
• 🏠 Lead was commonly used in water pipes due to its ease of manufacturing and joining, but it's now recommended to replace lead pipes in homes.
• 🚗 Lead was widely used as an additive in petrol from the 1920s until the late 1970s or 1980s to prevent engine knocking, but its harmful effects on health and the environment have led to the adoption of lead-free petrol.
• ♻️ The realization of lead's poisonous nature has led to a shift towards lead-free alternatives in various industries, including automotive and construction.

Q & A

Why is lead considered a very soft metal?

Lead is considered a very soft metal because it can be easily molded into various shapes, as demonstrated by the pot mentioned in the script.

What was the likely purpose of the lead pot found in the old lab?

The lead pot was likely used for holding strong acids due to lead's unreactive nature.

What is the significance of the white color on the lead pot?

The white color is due to lead oxide, which has formed as a result of oxidation over the years and was historically used in white paints.

How did lead oxide in paint react with the environment during Victorian times?

Lead oxide in paint reacted with sulfur in the air, which was abundant due to coal burning. This reaction resulted in a black color, causing white lead paint to eventually turn grey and then black.

What innovative use of lead oxide was discovered during World War II for submarines?

Lead oxide was used to paint submarines, allowing them to change color from white to black by applying a solution of sulfide and seawater, and back to white using hydrogen peroxide with seawater, for camouflage purposes.

Why is lead effective at stopping radioactive particles?

Lead is effective at stopping radioactive particles, particularly alpha and beta particles, due to its heavy atomic mass which provides substantial shielding.

How were lead bricks designed to prevent gaps that could allow radioactive particles to pass through?

Lead bricks were designed with grooves and pointed parts to ensure a tight fit when stacked together, preventing any direct line for radioactive particles to pass through.

What is lead glass and why is it used?

Lead glass is a type of glass with a high proportion of lead, making it very heavy but also allowing visibility while providing protection against radioactive materials.

Why was lead used in Roman times and what were the consequences?

Lead was used in Roman times for making sweeteners like lead acetate and for water pipes. However, its use was associated with poisoning and some suggest it contributed to the fall of the Roman Empire.

How was lead used in the automotive industry and why was it eventually phased out?

Lead was used as an additive in petrol to prevent engine knocking. It was phased out due to the realization of its poisonous nature and the environmental impact of lead emissions from car exhausts.

What precautions are advised for homes with lead pipes?

For homes with lead pipes, it is usually advisable to change them to prevent potential lead contamination in drinking water, even though lead pipes tend to develop a protective coating that reduces water contamination.

Outlines

00:00

🔧 Lead's Versatility and Historical Uses

This paragraph discusses the malleability of lead, its historical use in lab equipment for holding acids due to its unreactivity, and its role in paint production with lead oxide. It also touches on the chemical reaction of lead with sulfur in the air, leading to discoloration of white lead paint. A fascinating historical application is described where lead oxide was used to change the color of submarines for camouflage during wartime, exploiting the reaction with sulfur to darken the paint and hydrogen peroxide to revert it back to white. The paragraph also highlights lead's effectiveness in shielding against radioactive particles, particularly alpha and beta particles, and the use of lead bricks and lead glass in laboratories for safety.

05:03

🍷 The Historical Impact of Lead on Society

The second paragraph delves into lead's extensive history, beginning with its use by the Romans for making sweeteners and water pipes, and its unintended health consequences. It mentions the theory linking lead poisoning to the fall of the Roman Empire. The paragraph also covers the use of lead in petrol as an anti-knock agent from the 1920s to the late 20th century, which was later phased out due to the realization of its environmental and health hazards. The summary underscores the pervasiveness of lead in various aspects of human history and the gradual recognition of its dangers.

Keywords

💡Lead

Lead is a chemical element with the symbol Pb and atomic number 82. It is a heavy, malleable, and ductile metal that is both soft and dense. In the video, lead's properties are discussed in various contexts, such as its softness allowing it to be molded into different shapes, its use in holding strong acids due to its unreactivity, and its historical use in paints and gasoline due to its chemical properties.

💡Reactivity

Reactivity in chemistry refers to the tendency of a substance to undergo chemical reactions. The video explains that lead is very unreactive, which is why it was used for holding strong acids in the past. Its low reactivity also means it does not readily react with other substances, making it suitable for certain applications where stability is required.

💡Lead Oxide

Lead oxide is a chemical compound with the formula PbO. It is a white material that was historically used in paints, as mentioned in the video. The script describes how lead oxide would oxidize over time, turning into a white color, and how its reaction with sulfur in the air led to the discoloration of white lead paint.

💡Camouflage

Camouflage is the use of any combination of materials, coloration, or illumination for concealment, deception, or recognition in the visual spectrum. The video discusses an innovative use of lead oxide in submarine camouflage during wartime, where the paint would change color based on the environment to avoid detection.

💡Sulphur

Sulphur is a chemical element with the symbol S and atomic number 16. It is an abundant, multivalent non-metal. In the context of the video, sulphur is mentioned as a reactant with lead to form a black color, which was a problem for white lead paint but was exploited for the color-changing submarine camouflage.

💡Submarine

A submarine is a watercraft capable of independent operation underwater. The video script provides an interesting historical account of how submarines were painted with lead oxide to change their color for stealth purposes during military operations, illustrating the practical application of chemical properties in warfare.

💡Radioactive Particles

Radioactive particles are tiny pieces of matter that emit radiation as they decay. The video explains that lead is effective at stopping these particles, particularly alpha and beta particles, due to its dense atomic structure. This property makes lead useful in shielding materials for radioactive environments.

💡Alpha Particles

Alpha particles are helium nuclei consisting of two protons and two neutrons. They are a type of ionizing radiation. The script mentions that lead is particularly good at stopping alpha particles, which is why it is used in shielding materials to protect against radiation.

💡Beta Particles

Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei during beta decay. The video notes that lead can effectively block beta particles, further emphasizing its use in radiation protection.

💡Lead Glass

Lead glass, also known as lead crystal or flint glass, is a type of glass that contains a significant amount of lead. The video describes how lead glass is heavy and can be used for viewing or handling radioactive materials due to its opacity and radiation shielding properties.

💡Tetraethyl Lead

Tetraethyl lead is an organolead compound with the chemical formula Pb(C2H5)4. It was once widely used as an antiknock agent in gasoline. The video script recounts the history of its use and the eventual realization of its toxicity, leading to the adoption of lead-free petrol.

Highlights

Lead is a very soft metal that can be easily molded into various shapes.

Lead's reactivity makes it suitable for holding strong acids.

Lead oxide's white color was historically used in paints.

Lead oxide reacts with sulfur in the air, causing white paint to turn grey or black over time.

Professor Leslie Crombie used lead oxide for camouflaging submarines during wartime.

Submarines were painted with lead oxide and then treated with a sulphide solution to turn black for coastal camouflage.

Hydrogen peroxide and seawater were used to revert the submarine's paint back to white for open sea camouflage.

Lead is effective at blocking radioactive particles, especially alpha and beta particles.

Lead bricks with grooves and pointed parts are used to create radiation shielding walls with no gaps.

Lead glass allows visibility while providing radiation protection.

Lead was widely used in the past for water pipes and as an additive in petrol.

The use of lead in petrol caused environmental pollution and health issues, leading to the adoption of lead-free petrol.

Lead acetate was used by the Romans to sweeten wine, despite its poisonous effects.

Excessive lead exposure may have contributed to the fall of the Roman Empire.

Lead's properties have made it useful in various applications throughout history, despite its toxicity.

Transcripts

Lead is a very soft metal and it’s easily moulded into all sorts

of shapes. This is a pot, I’m not sure what it is from, I got it

from an old lab that was being closed down so it was

probably made for holding a strong acid because lead is very

unreactive. You can see rather nicely here the white colour of

lead oxide because it has oxidised over the years and this is

the white material that was used for paints.

This white lead paint that people use, the oxide of lead, had

one rather unfortunate consequence that it reacts with

sulphur in the air and in Victorian times when people burnt

coal they produced a lot of sulphur, and the sulphur reacted

with the lead to give a black colour which made the white

paint eventually turn grey and if you waited long enough

black. And this effect was exploited by one of my former

colleagues here Professor Leslie Crombie, who during the war

was working for the British admiralty in their research labs on

the camouflaging of submarines. Now if you want your

submarine not to be seen, when it is well away from the

coast it needs to be white because if you have a white

submarine it does not show up against the sky but, if you are

trying to slip into the coast at night and not be seen you need

the submarine to be black. So Leslie came up with the idea of

painting the submarine with lead oxide and when it was going

near the coast, some sailors went out on to the outside of the

ship and sloshed over a solution of sulphide and seawater and

the paint turned black. And so you could then go into the

coast, drop your agent, do whatever secret things you

wanted to do, and then when you went away from the coast

they sloshed hydrogen peroxide with seawater, which turned

the sulphite into sulphate, and lead sulphate is white so your

submarine went white again. So you could change the colour

of your submarine to suit what you were doing in the military

operation and nobody would see you.

And that was a real thing that happened?

Yes, that was a real thing. I don’t know how widely it was

used but they actually tried it out and it worked. So they just

needed to take the chemicals and they could add the

seawater to make the solution to put on the submarine.

The other very important property of lead is that because the

lead atom is heavy it is very good at stopping radioactive

particles particularly alpha particles, which are helium nuclei

those are the nucleus of the helium atom, or beta particles

which are electrons.

What you should find that if we put this in the way, it should

stop counting almost immediately so let us see if that works.

There we go straight back down to background and if we take

it away, and it picks back up again.

And so people who are working with radioactive samples used

to use, and still use, bricks made out of lead. So here are two

of the bricks and you can see this is a small one and this one

is rather thinner. The problem is that if you start building

these bricks into a wall, there is always a chance that when

you have two bits together there might be a slight gap

between the two bricks and some of the radioactive particles

may go between them. So to avoid this the bricks are made

with groves in it, and a pointed part here, so that when you

put them together there is absolutely no way that anything

can go through because you can’t have a direct line through

it. Now the trouble is of course you can’t see anything

through it, so if you have an experiment where you want to

handle radioactive material inside a container and manipulate

it you can’t make the whole container of lead because you

can’t see what is going on inside. And so for that, people

have developed lead glass, of which this is a sample and it is

immensely heavy, but this is glass and there is really a large

amount of lead that has been put in it. And some of the fancy

crystals that your grandmothers or your ancestors might have

had, had a bit of lead in the glass. This has got a really high

proportion of lead in the glass which is probably why the

glass is yellow rather than the white colour that you normally

have with glass. But windows like this can be used for

handling really quite radioactive materials behind them. The

colour is rather nice isn’t it?

Good.

But it is very heavy, so…

Well, lead has had a very long history; it was one of the first

metals to be widely used. The Romans used this for drinking

materials. There is also lead acetate, that is a compound of

lead and vinegar is meant to taste sweet and the Romans

added this to their wine to make it sweeter. The fact that it

was really very poisonous and caused, possibly even caused

madness, was not really widely recognised. In fact some

people have suggested that part of the collapse of the Roman

Empire was due to too much lead. Lead was very widely used

in the UK for water pipes because it’s easy to manufacture

and to join together. It tends not to have been very

dangerous in terms of drinking water because it gets a

coating on the surface so you do not get much lead in the

water; though if you do have a house with lead pipes in, it is

usually advisable to change them. It’s again, it was used very

widely from the 1920s up till the late 70s or 80s as an

additive for petrol. In the old days when petrol engines were

first introduced, when you came to a hill and put down the

accelerator of your car, the engine started misfiring, so-called

‘pinking’, and the whole thing shook. So it was really quite

difficult to drive up hills, but then it was discovered that you

could put in a compound, so-called tetraethyl lead, which was

really very poisonous, but the guy who discovered it washed

his hands in public at a press conference saying “look it’s so

safe”, despite the fact that there were people dying in his

factory. So it was very widely adopted and so it was only in

quite recent times that it was realised how much lead was

being blown out into the atmosphere in car exhausts. And so

it’s now almost everywhere we have lead-free petrol as a

result of people realising the poison-ness of lead.