Age of Enlightenment.

Age of Enlightenment was an important time in history. It was in XVII and XVIII centuries.

During the Enlightenment era, science and philosophy actively developed in culture.

Rene Descartes, Francis Bacon, John Locke, and Immanuel Kant were philosophers of that time.

Discoveries were made in biology, physics, and chemistry.

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Free radical

Free radical or radical the name of particles in chemistry. Free radicals can be gaseous, liquid, and solid.

These atoms and molecules have a short lifespan.

Free radicals enter into chemical reactions with metals.

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Isotope.

Isotope (Ισότοπο) means isos (ἴσος) "equal" and topos (τόπος) "place". These are varieties of the same chemical element.

Isotopes have the same atomic number, but they have different mass numbers.

These elements are studied in chemistry.

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Iodine.

Iodine is a chemical element. Its symbol is I. This element has its own isotopes.

Iodine can be black or purple in color. Also, it has a smell.

This mineral is found in some foods.

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Minerals.

Minerals, also known as mineral species are parts of rocks and chemical elements.

There are many different minerals. Calcium (Ca), phosphorus (P), and iodine are minerals, too.

These elements are found in the bowels of the Earth.

Minerals are used in various fields.

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Astronomy.

Astronomy is a science about space. It studies different objects in the universe. Our Solar System, planets, stars, comets, satellites, and galazxies are studied by astronomy. Other sciences, such as: chemistry, physics, and mathematics are important for it.

Since ancient times people were interested in the sky and stars. Astronomy was studied in Ancient Greece, Egypt, and Babylon. Epoch changed and science changed, too.

Nicolasus Copernicus, Giordano Bruno, and Galileo Galilei did a lot of important things for astronomy. This difficult science started developing.

Now, scientists use telescopes for space study. New galaxies and planets are being studied nowadays. The universe is very large in it there are many different stars and planets.

Our planet is Earth. It's the third planet from the Sun. The planet situated in the Solar System. The Sun is a star. The Moon is a satellite of the Earth. Also, in the Solar System there are other planets and asteroid belt. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune are planets. They are different but revolve around the Sun.

The Milky Way is a galaxy where the Solar System locate. It can be notice during a bright night.

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Chemistry.

Chemistry is one of the most important and interesting school subjects. This science has similar parts with physics. There are many formulas and tables.

H₂O is a formula of water. Students can conduct experiments in special rooms during lessons. 

Chemical elements everywhere. Foods, furniture, our body; all of them have chemical elements.

This science may be difficult for someone. Thanks to chemestry we know about salt, sugar, and fats. It is necessary to know in life.

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Physics.

Physics is one of the hardest school subjects and sciences. Therefore this subject is taught in high schools.

Some laws of phycics have been discovered in ancient times. There are complex physical formulas. Atoms and molecules are an important part of this hard science. Light and electricity work by the laws of physics.

Astronauts must know physics for their work. Ordinary people also should know that science. For example, water is a good conductor of electricity. Electrical items can not be touched by wet hands.

Famous scientists who studied physics: Aristotle, Isaac Newton, Albert Einstein. Today scientists study this science too.

Perhaps physics is more difficult than mathematics. If math is necessary to understand, for physics than physics is more difficult. There is a common subject on physics-chemestry. This science also has complicated formulas.

It was an essay about one of the most complex subjects. Next time will be another.

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