Energy & Environment

Non Metals share electrons. All the electrons get used so there are no free electrons. Non metals are badconductors. They are insulators.

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All elements want to have electronic arrangements like noble gases

Noble Gas ElectronArrangement

He (Helium) 2Ne (Neon) 2,8Ar (Argon) 2,8,8Kr (Krypton) 2,8,18,8

Metals give electrons away. This provides free electrons.Metals are good conductors of electricity.

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How do non metals and metals achieve this?

Electricity is a stream of electrons flowing from one point to another.

The entire study of electricity is based on the

Electron Theory

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AtomMolecule

Cu 11+

Ion

Match these terms to the figures

Explain why this ion has +11 charge

Metals are good conductors of electricity as electrons can move freely

Metal Ions

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Noble Gas ElectronArrangement

He (Helium) 2Ne (Neon) 2,8Ar (Argon) 2,8,8Kr (Krypton) 2,8,18,8

How can it get this arrangement?

It could share electrons with another 4 silicon atoms...

Noble Gas ElectronArrangement

He (Helium) 2Ne (Neon) 2,8Ar (Argon) 2,8,8Kr (Krypton) 2,8,18,8

Silicon naturally wants an electronic arrangement

like Argon

This is called a Lattice

LatticeKeeps bonding together until something stops

them

That’s enough chemistry for just now.

Now lets have a look at energy

Renewables

PollutingRun out

Climate change

Energy Resources can be separated into 2 categories

NonRenewablesConsumed much faster than can be created

Always around us, are part of our natural environment

Coal

Will not run out

Non-PollutingLess reliance on other sources/countries

Heat LightChemical

On a sunny day, the sun gives off approximately 1,000 watts of energy/m2 of the planet's surface.

If we could collect all of that energy, we could easily power our homes for free

A solar cell is a device that uses the photoelectric effect to generate electricity from light.The photoelectric effect is the flow of electric current in a material when the material is exposed to light.

A solar panel is a made from many solar cells

The simplest type of solar cell is made from silicon which is a semiconductor

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MetalsNon

Metals

Silicon is a Non Metal

A semiconductor is between a conductor and an insulator

Silicon naturally wants an electronic arrangement

like Argon14x Protons

Noble Gas ElectronArrangement

He (Helium) 2Ne (Neon) 2,8Ar (Argon) 2,8,8Kr (Krypton) 2,8,18,8

What does an atom of silicon look like?

Noble Gas ElectronArrangement

He (Helium) 2Ne (Neon) 2,8Ar (Argon) 2,8,8Kr (Krypton) 2,8,18,8

Pure Semiconductor

So how can we make a silicon lattice into a

conductor of electricity?

By adding other elements to semiconductors like silicon we can change its conductivity

Doping is the process of adding a tiny amount other elements to a pure semiconductor such as silicon.

This increases its ability to conduct current as if effects the electron arrangement of the lattice.

There are two forms of doping, p-type and n-type.

Adding small amountsof other elements toimprove performance

p for positive n for negative

Adding an element with more electrons than are required

N (Negative) Doping

Extra ElectronFree to move about the lattice

Adding an element with less electrons than are needed

P (Positive) Doping

Missing ElectronA ‘hole’ for an electron has

been created

p-type(Positive)Missing electrons

n-type(Negative)Free electrons

p-n junctionacts like a diode. Allows electrons to move from P to N side only -

p-type and n-type semiconductors are used in solar panels

p-n junction forms an electronic field.Acts like a diode. Allows electrons to move from P to N side only

Sunlight loosens electrons, creating free electrons

-Because electrons are leaving the N-type side, there are spaces for the electrons created

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Electric current produced

Photovoltaic Video

A solar cell can only absorb 15-25% of the sun's energy

Too much resistance inside the semiconductorIf the photon doesn't have enough energy, nothing happens

Silicon isn't as efficient at moving electrons as a conductor

An array of solar panels are needed to produce enough power

Inverter

Battery Direct current must be changed to alternating current so we can use it

We use Alternating Current (AC) in our buildings as it’s better at long distance travelling

Cells must be protected from damage and moisture

So we can use the power when we want it

Portable solar lights open up opportunities for many people in rural areas.

Children are able to study at night and women feel safer going outdoors in the dark

This boy is able to charge mobile phones off his solar lamp and makes money!

Runtime HIGH Setting: Up to 6 hours Runtime LOW Setting: Up to 30 hours Charge: 3-4 hours

They have no moving parts so need little maintenance therefore they are cheap to run

Solar power is good when grid connection or fuel transport is difficult, costly or impossible. e.g. satellites, hilly areas, remote locations

Once installed they produce energy without waste or pollution

Solar energy systems do not work in night

Solar cells need to be handled carefully so can be difficult to transport

Solar cells are currently costly and require a large initial capital investment

Type of light Efficiency(Lightintensity(lumens)/watt)

RatedLife(Hours)

Durability Power consumption

Kerosene Lantern

0.03 Supply of kerosene

Fragile &dangerous

0.04-0.06liters/hour

Incandescent 5-18 1000 Very fragile 5 W

CompactFluorescent

30-79 65000-15000

Very fragile 4W

White Light Emitting diodes (WLED)

25-50 50000 durable 1W

1. What is P-type and N-type semiconductors?2. Explain how a solar cell works3. Why is an inverter important in a

Photovoltaic System?4. Give 3x advantages of solar cells

p for positive n for negative

DC to AC