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The Solar System
The Solar System

The Solar System

 

The universe is filled with billions of star systems. Located inside galaxies, these cosmic arrangements are made up of at least one star and all the objects that travel around it, including planets, dwarf planets, moons, asteroids, comets, and meteoroids. The star system we’re most familiar with, of course, is our own.

 

Our Home:

If you were to look at a giant picture of space, zoom in on the Milky Way galaxy, and then zoom in again on one of its outer spiral arms, you’d find the solar system. Astronomers believe it formed about 4.5 billion years ago, when a massive interstellar cloud of gas and dust collapsed on itself, giving rise to the star that anchors our solar system—that big ball of warmth known as the sun.

Along with the sun, our cosmic neighbourhood includes the eight major planets. The closest to the sun is Mercury, followed by Venus, Earth, and Mars. These are known as terrestrial planets, because they’re solid and rocky. Beyond the orbit of Mars, you’ll find the main asteroid belt, a region of space rocks left over from the formation of the planets. Next come the much bigger gas giants Jupiter and Saturn, which is known for its large ring systems made of ice, rock, or both. Farther out are the ice giants Uranus and Neptune. Beyond that, a host of smaller icy worlds congregate in an enormous stretch of space called the Kuiper Belt. Perhaps the most famous resident there is Pluto. Once considered the ninth planet, Pluto is now officially classified as a dwarf planet, along with three other objects and Ceres in the asteroid belt.

 

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Gravity (basic)
Gravity (basic)

Gravitation

It is a natural phenomenon by which all things with mass and energy including planets, stars, moons, galaxies etc. are attracted to one another.

We all feel the gravitation of earth as we live on it. It pulls us with a force equal to our weight. Weight of all the physical objects and the atmosphere etc. on earth is because of the gravity. Tides in the ocean are caused because of the gravity of the moon.

Newton’s theory of gravitation

Through time many scientists have theorised about gravity or gravitation and English mathematician Sir Isaac Newton is considered one of the greatest contributor. He in 1687 published Principia which hypothesizes the inverse square law of Universal gravitation. The equation is the following:

Where           F = gravitational force between two objects

           M1, M2 = mass of the two objects

                       R = distance between the two objects

 

 

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Elements (metals and non metals)
Elements (metals and non metals)

Elements (Metals and Non-metals)

Elements are the fundamental building block of all the matter that we see all around us like the river, rock, earth, the sun, the moon, air, everything else that we can observe.

Elements are grouped as metals or non- metals.

Metals and non-metals are classified according to their physical properties and also their chemical properties and the arrangement of the electrons in the atoms.

The properties of both metal and non- metal are shown below in the table.

                                                                      Physical Properties

                                    Metals

                                  Nonmetals

Good electrical conductors and heat conductors.

 

Poor conductors of heat and electricity.

 

Malleable - can be beaten into thin sheets.

 

Brittle - if a solid.

 

Ductile - can be stretched into wire.

 

Nonductile.

 

Possess metallic lustre.

 

Do not possess metallic luster.

Opaque as thin sheet.

 

Transparent as a thin sheet.

 

Solid at room temperature (except Hg).

Solids, liquids or gases at room temperature.

 

 

                                                     Chemical Properties

 

Usually have 1-3 electrons in their outer shell.

 

Usually have 4-8 electrons in their outer shell.

 

Lose their valence electrons easily.

Gain or share valence electrons easily.

 

Form oxides that are basic.

Form oxides that are acidic.

 

Are good reducing agents.

Are good oxidizing agents.

 

Have lower electronegativities.

Have higher electronegativities.

 

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Atoms and Molecules
Atoms and Molecules

 

All matters (solid, liquid, gas, plasma), that we see around us are made up of atoms and molecules.

What are atoms?

Atoms are the fundamental unit of all the elements. It is what gives the physical and chemical properties to metals and nonmetals.

To further break an atom will result in subatomic particles like electrons, protons, and neutrons. Only the combination of these subatomic particles which is stable gives an element its characteristics.

*There are also many theoretical and discovered subatomic particles like bosons and fermions.

There are more than 110 discovered elements (atoms) as shown in the periodic table.

Each atom consists of nucleus and the electrons revolving around it. Protons and neutrons are itself in the nucleus.

 

                                          What_are_atoms                       

     Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and several neutrons. Only the most common variety of hydrogen has no neutrons. More than 99.94% of an atom's mass is in the nucleus. The protons have a positive electric charge, the electrons have a negative electric charge, and the neutrons have no electric charge. If the number of protons and electrons are equal, then the atom is electrically neutral. If an atom has more or fewer electrons than protons, then it has an overall negative or positive charge, respectively – such atoms are called ions.

The number of protons in the nucleus is the atomic number and it defines to which chemical element the atom belongs. For example, any atom that contains 29 protons is copper. The number of neutrons defines the isotope of the element. Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to associate and dissociate is responsible for most of the physical changes observed in nature. Chemistry is the discipline that studies these changes.

What is a molecule?

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge.

A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H2O). Following figure is representation of water molecule. The red sphere is oxygen atom and the yellow spheres are hydrogen atom, bonded together with covalent bond, thus forming a water molecule.

 

                                                                       What_are_atoms

Molecules as components of matter are common. They also make up most of the oceans and atmosphere. Most organic substances are molecules. The substances of life are molecules, e.g. proteins, the amino acids they are made of, the nucleic acids (DNA & RNA), sugars, carbohydrates, fats, and vitamins. The nutrient minerals ordinarily are not molecules, e.g. iron sulfate.

 

However, the majority of familiar solid substances on Earth are not made of molecules. These include all of the minerals that make up the substance of the Earth, soil, dirt, sand, clay, pebbles, rocks, boulders, bedrock, the molten interior, and the core of the Earth. All of these contain many chemical bonds, but are not made of identifiable molecules.

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States of matter (Solid, Liquid, Gas, Plasma)
States of matter (Solid, Liquid, Gas, Plasma)

States of matter

All the matter around us exists in different states. It means they all are varying with respect to appearance, physical form, chemical properties, interaction with each other, etc. Previously there were only three states of matter, but it has long changed to few more like plasma, Bose- Einstein condensate etc. Only main three states (solid, liquid, gas) and plasma are studied till the graduation.

SOLID

In solid state the objects are rigid, as the individual particles (Atoms or molecules) are tightly packed.  The electrons of each atom are constantly in motion, so the atoms have a small vibration, but they are fixed in their position. Because of this, particles in a solid have very low kinetic energy. As a result, solids have fixed shape or definite volume. And it can be only changed by external force or pressure.

In crystalline solids, the particles are packed in orderly manner, in repeating matrix. There are various crystal structures, and the same substance can have more than one structure (or solid phase). For example, iron has a body-centred cubic structure at temperatures below 912 °C, and a face-centred cubic structure between 912 and 1394 °C. Ice has fifteen known crystal structures, or fifteen solid phases, which exist at various temperatures and pressures.

Glasses and other non-crystalline, amorphous solids without long-range order are not thermal equilibrium ground states; therefore, they are described below as nonclassical states of matter.

Solids can be transformed into liquids by melting and can also change directly into gases through the process of sublimation.

 

            SOLID                                LIQUID                                GAS   States_of_matter     

LIQUID

In liquids, the particles have a great deal of space between them, but not as great as gases (where the particles are free to move around). The particles in liquid are bound together but do not have a fixed shape. They take the shape of containers where they are placed in. It is nearly incompressible fluid and retains a (nearly) constant volume independent of pressure.
The volume of liquid is definite at same pressure and temperature. The volume of a liquid depends on both pressure and temperature.

GAS

A gas does not have a definite shape as the particles are not held together by strong forces and wander freely. In a gas, the molecules have enough kinetic energy so that the effect of intermolecular forces is small (or zero for an ideal gas), and the typical distance between neighbouring molecules is much greater than the molecular size. A gas has no definite shape or volume but occupies the entire container in which it is confined. A liquid may be converted to a gas by heating at constant pressure to the boiling point, or else by reducing the pressure at constant temperature.

Plasma

Plasma is very similar to gas in appearance and does not have a definite shape or size. Unlike gases, plasmas are electrically conductive, produce magnetic fields and electric currents, and respond strongly to electromagnetic forces. Positively charged nuclei swim in a "sea" of freely moving disassociated electrons, similar to the way such charges exist in conductive metal, where this electron sea allows matter in the plasma state to conduct electricity.

A normal gas can be converted to plasma by exposing it to very high voltage or very high temperature.

The plasma state is often misunderstood, and although not freely existing under normal conditions on Earth, it is quite commonly generated by either lightning, electric sparks, fluorescent lights, neon lights or in plasma televisions. The Sun's corona, some types of flame, and stars are all examples of illuminated matter in the plasma state.

 

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Thermodynamics
Thermodynamics

Thermodynamics

Thermodynamics can be defined as the science of energy. Energy can be defined as something which changes the physical property or chemical property of an object.

The word thermodynamics has been derived from Greek which means “heat power, which is the most descriptive of the earlier efforts to convert heat into power. Thermodynamics now is interpreted to include all aspects of energy and energy transformations, including power generation, refrigeration, and relationships among properties of matter.