SomeFacts | Science

Science

What is the smallest particle of all?
No one is sure. Atoms are made of protons, neutrons and electrons. In ...

How many kinds of particle are there?
Since the 1920s, scientists have discovered that there are at least ...

Who split the atom?
Electrons can be split off from atoms easily, but in 1919, the New ...

What is an ion?
An ion is an atom that has either lost one or a few electrons, making ...

What is the nucleus?
Most of an atom is empty space, but right at its center is a very ...

What holds atoms together?
Electrons are held to the nucleus by electrical attraction - because ...

What are electrons?
Electrons are the very tiny electrically charged particles that whizz ...

What is a molecule?
Quite often, atoms cannot exist by themselves, and must always join ...

How big are atoms?
Atoms are about a ten millionth of a millimeter across and weigh 100 ...

How does pressure change?
If you squeeze a gas into half the space, the pressure doubles (as ...

What is pressure?
Pressure is the amount of force pressing on something. Air pressure ...

When do things melt?
Things melt from solid to liquid on reaching a temperature called the ...

When do things boil?
Things boil from liquid to gas when they reach boiling point, which ...

When do things freeze?
Things freeze from liquid to solid when they reach the freezing ...

What is a plasma?
A plasma is the rare fourth state of matter. It occurs only when a ...

What substance has the lowest freezing point?
Mercury has the lowest freezing point of any metal -38.87°C ...

What substance has the highest melting point?
The metal with the highest melting point is tungsten, which melts at ...

What is the lightest element?
The lightest element is hydrogen. It has just one proton in its ...

What are the lanthanides?
The lanthanides are a group of 15 elements in the middle of the ...

What is atomic mass?
Atomic mass is the 'weight' of one whole atom of a substance - which ...

Who discovered radium?
The Polish-French physicist Marie Curie (1867-1934), born Marya ...

Why is carbon so special?
Carbon is the most friendly element in the Universe. With four ...

Why are some elements reactive?
Elements are reactive if they readily gain or lose electrons. ...

What are noble gases?
Group 0 is the furthest right-hand column of the periodic table. This ...

What is a metal?
Most people can recognize a metal. It is hard, dense and shiny, and ...

What are the transition metals?
Transition metals are the metals in the middle of the periodic table, ...

What is the heaviest element?
The heaviest is hahnium. It has 105 protons and 157 neutrons in its ...

How many elements are there?
New elements are discovered every so often, but the total number ...

What’s the air made of?
Pure air is 78.9% nitrogen, 20.95% oxygen. There are traces of argon ...

What’s the sea made of?
The sea is water with oxygen, carbon dioxide, nitrogen and various ...

What is a chemical formula?
A chemical formula is a shorthand way of describing an atom, an ion ...

What is a mixture?
Mixtures are substances that contain several chemical elements or ...

What is electrolysis?
Electrolysis is a chemical reaction caused when an electric current ...

How do batteries work?
Batteries create electric currents from the reaction between two ...

Why do things float?
When an object is immersed in water, the weight of the object pushes ...

What is half-life?
No-one can predict when an atomic nucleus will decay. But scientists ...

Who invented the atomic bomb?
The first atomic bombs were developed in the USA towards the end of ...

How can radioactivity be used to indicate age?
Radioactivity proceeds at a very steady rate. So by measuring how ...

What does radiation do to you?
It causes radiation sickness. With a very high dose, the victim dies ...

How do nuclear power stations work?
Inside the reactor there are fuel rods made from pellets of uranium ...

What is an atomic bomb?
An atomic bomb or A-bomb is one of the two main kinds of nuclear ...

What is nuclear fission?
Nuclear fission releases nuclear energy by splitting big atomic ...

What is nuclear fusion?
Nuclear energy is released by fusing or joining together small atoms ...

How do things dissolve?
When solids dissolve in liquid, it may look as if the solid ...

What is cellulose?
Cellulose is a natural fiber, found in the walls of all plant cells. ...

How is oil refined?
Oil drilled from the ground, called crude oil, is separated into ...

What is a polymer?
Polymers are substances made from long chains of thousands of small ...

Who discovered the shape of DNA?
The discovery in 1953 that every molecule of DNA is shaped like a ...

What are buckyballs?
Before 1990, carbon was known in two main forms or allotropes ...

Who made the first waterwheels?
Nobody knows for sure, but wheels turned by water to generate power ...

What is hydroelectric power?
Hydroelectric power or HEP is electricity generated by turbines ...

Why does sweating keep you cool?
Because sweat is nearly all water, and water needs warmth to turn to ...

Why do plants need water?
Plants contain an even higher proportion of water than the human ...

How much water is there in the body?
Water is found in nearly every cell of the body, which is why human ...

What is heavy water?
Heavy water is deuterium oxide - water that is a little heavier than ...

What is hydraulic power?
Fluids like water are incompressible - that is, they cannot be ...

What’s the fastest thing in the Universe?
Light, which travels at 300,000 km (186,000 miles) per second. This ...

Who was Einstein?
Albert Einstein (1897-1955) was the scientific genius who transformed ...

What is Special Relativity?
The theory of Special Relativity shows how both space and time can be ...

What’s the difference between velocity and speed?
Speed is how fast something is going. Velocity is how fast something ...

What is uniform motion?
Uniform motion is when an object carries on travelling at exactly the ...

What is a turning force?
When something fixed in one place, called a fulcrum, is pushed or ...

What is a knock-on effect?
When two objects collide, their combined momentum remains the same, ...

What happens with every action?
This is Newton's Third Law of Motion for every action, there is an ...

What is acceleration?
Acceleration is how fast something gains speed. The larger the force ...

What’s the difference between inertia and momentum?
Inertia is the tendency of things to stay still unless they are ...

What was Newton’s breakthrough?
Sir Isaac Newton's breakthrough, in 1665, was to realize that all ...

What are carbohydrates?
Carbohydrates are chemicals made only of carbon, hydrogen and oxygen ...

What is the carbon cycle?
Carbon circulates like this: animals breathe out carbon as carbon ...

What are aromatics?
Benzene is a clear liquid organic chemical found in coal tar. It can ...

What is a carbon chain?
Carbon atoms often link together like the links of a chain to form ...

How is plastic made?
Most plastics are made from ethene, one of the products of cracked ...

What is oil?
Oils are thick liquids that won't mix with water. Mineral oils used ...

How is natural oil made?
Oil is formed from tiny plants and animals that lived in warm seas ...

Why do satellites go round the Earth?
Satellites are whizzing through space at exactly the right height for ...

Does gravity vary?
An object's gravitational pull varies with its mass and its distance. ...

Why can you jump higher on the Moon?
The Moon is much smaller than the Earth, so its gravity is much ...

How fast does a stone fall?
At first, the stone falls faster and faster at a rate of 9.8 metres ...

What is friction?
Friction is the force between two things rubbing together, which may ...

How is force measured?
Force is measured in newtons, in honor of Sir Isaac Newton. A newton ...

What did a great scientist learn from an apple?
The mathematician and physicist Sir Isaac Newton is said to have ...

What did Galileo do on the Tower of Pisa?
The Italian scientist and astronomer Galileo Galilei (1564-1642) is ...

What is gravity?
Gravity is the invisible force of attraction between every bit of ...

What is power?
Power is the rate at which work is done - a high-powered engine is an ...

What’s the difference between mass and weight?
Mass is the amount of matter in an object. It is the same wherever ...

What is an echo?
An echo is when you shout in a large empty hall or in a tunnel, and ...

What is sound frequency?
Some sounds, like a car's squealing brakes, are very high-pitched. ...

What is resonance?
If allowed to vibrate freely, every object always tends to vibrate at ...

Why is the Earth like a magnet?
As the Earth spins, the swirling of its iron core turns the core into ...

What is a lodestone?
Thousands of years before people learned how to make steel magnets, ...

What is a magnetic field?
The magnetic field is the area around the magnet in which its effects ...

How does electric light work?
An electric bulb has a very thin filament of tungsten wire inside a ...

What is an alternating current?
A direct current (DC) flows in one direction only. Most hand-held ...

What is resistance?
Not all substances conduct electric currents equally well. Resistance ...

What is a volt?
Electrical current flows as long as there is a difference in charge ...

Who invented transistors?
Transistors were invented by three scientists working at the Bell ...

What is a semi-conductor?
Semi-conductors are materials such as silicon or germanium, which are ...

What are the best conductors?
The best conductors are metals like copper and silver. Water is also ...

How do electric currents flow?
The charge in an electric current is electrons that have broken free ...

What is a silicon chip?
A silicon chip is an electronic circuit implanted in a small crystal ...

What is an electric current?
A current is a continuous stream of electrical charge. It happens ...

Who made the first radio broadcast?
Italian inventor Guglielmo Marconi first sent radio signals over 1.6 ...

How do TV signals travel?
TV signals travel in one of three ways. Terrestrial broadcasts are ...

How do CT scans work?
CT (computed tomography) scans run X-ray beams right round the body, ...

How do X-rays see through you?
X-rays are stopped only by the bones and especially dense bits of the ...

What is infrared?
Infrared is light with wavelengths too long for the human eye to ...

How does a prism split colors?
Prisms split white light into separate colors by refracting (bending) ...

Why can’t you see ultraviolet?
Ultraviolet light is light with wavelengths too short for the human ...

What is an incident ray?
When scientists talk about reflections, they distinguish between the ...

Why is the sky blue?
Sunlight is white - which means it contains all the colors of the ...

How do things absorb light?
When light rays hit a surface, some bounce off, but others are ...

What are photons?
Photons are almost infinitesimally small particles of light. They ...

Does light travel in waves?
In the last century, most scientists believed light did travel in ...

How do mirrors work?
Most mirrors are made of ordinary glass, but the back is silvered ...

Why is the sun red?
The sun is only red at sunrise and sunset, when the sun is low in the ...

How do fiber optic cables bend light?
Actually they don't bend light, but reflect it round comers. Inside a ...

How is light bent?
Light rays are bent when they are refracted. This happens when they ...

How is temperature measured?
Temperature is usually measured with a thermometer. Some thermometers ...

How do you convert Fahrenheit to Celsius?
You can convert from Fahrenheit to Celsius by subtracting 32 then ...

What’s the difference between heat and temperature?
Heat is molecules moving. It is a form of energy the combined energy ...

What is conduction?
Conduction is one of the three ways in which heat moves. It involves ...

What’s absolute zero?
Absolute zero is the coldest possible temperature, the temperature at ...

How are energy and mass linked?
Energy is a form of mass; mass is a form of energy. In nuclear ...

What is energy efficiency?
Some machines waste a great deal of energy, while others waste very ...

How is energy conserved?
Energy can be neither created nor destroyed. When energy is converted ...