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Following is the Chemistry Important Matter and Its Nature General Science Notes One-liner Notes for RRB Railway exams. You can download this Chemistry PDF useful for all competitive exams of UPSC (Civil services including IAS), SSC CGL, TNPSC etc.
Anything which has mass and occupies some space is called matter. Each and everything which we see around us is matter. What about air? Neither we can see it nor has it mass!! Is it also matter? The answer is yes! Air is a matter. We can’t see it but it occupies space. That is why only a limited amount of air can be filled in a balloon.
Matter and Its Nature General Science Notes For SSC CGL & RRB Exams
- Matter exists in three different states in Physical Form
- Solids – Molecules are closely packed. It is structural rigidity to changes of shape or volume
- Liquids – Molecular Bonds in a liquid are weaker than those in a solid but stronger than those in gases
- Gases – Molecular Bonds in a gas are loosely held and weaker than those in solids and liquids
| v Boiling Point | The boiling point of a substance is the temperature at which the vapor pressure of the liquid equals the Atmospheric Pressure |
| v Melting Point | The temperature at which the solid exists in equilibrium with its liquid under an external pressure of one atmosphere. |
| v Evaporation | Evaporation is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure |
| v Freezing Point | Freezing point is the temperature at which a liquid becomes a solid at normal atmospheric pressure |
| v Surface Tension | Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible |
| v Decantation | Is a process to separate mixtures by removing a liquid layer that is free of a precipitate. The purpose may be to obtain the liquid free from particulates or to recover the precipitate |
| v Specific Gravity | The ratio of the mass of a substance to the mass of a reference substance for the same given volume |
| v Filtration | Filtration is process that separate solids from fluids by adding a medium through which only the fluid can pass through |
| v Sublimation | Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase. |
| v Diffusion | Diffusion is defined as the movement of Gas into open space or diffusion into another gas |
| v Effusion | Movement of gas through a tiny hole is defined as effusion |
| v Emulsion | A fine dispersion of minute droplets of one liquid into another in which it is not soluble or miscible |
| v Viscosity | The state of being thick, sticky, and semi-fluid in consistency, due to internal friction |
| v Liquids at high altitudes boil at lower temperature due to low atmospheric pressure at high altitudes | |
| v Evaporation takes place only on the surface of Liquids | |
| v The melting point of Ice decreases with Increase in Pressure | |
| v Pure water has a maximum density of 1 gm/cm 3 at 4 Degrees Celsius | |
| v Surface Tension decreases with Increase in temperature | |
| v Spherical Shape of Liquid Droplets is due to the property of Surface Tension in Liquids | |
| v Boiling Point and Evaporation of a liquid differ in a basic point that Evaporation occurs at all temperatures whereas Boiling Point of a liquid occurs at specific Temperature |
- Total 112 elements are known till date of which 92 are naturally occurring elements rest are results of artificial transmutation. There are 88 metals, 18 non metals and 6 metalloids.
- All matter is made up of Atoms which is the smallest particle of the element that consists of three fundamental units – Protons, electrons and neutrons.
| v Discovery of Atomic Nucleus | v Ernest Rutherford based on Geiger–Marsden Gold Foil Experiment |
| v Discovery of Protons | v E Goldstein |
| v Discovery of Electrons | v J J Thomson |
| v Discovery of Neutrons | v James Chadwick |
- Nucleus is the center of the Atom contains the neutral charges Neutrons and Positively charged Protons, the electrons revolve around the nucleus of an atom
- Protons, electrons and Neutrons are called sub-atomic particle.
- Each sub-atomic particle has an anti-particle with an opposite electric Charge
- “Positron” is not a sub-atomic particle but an anti-particle of electron which has same mass as electron – 9.10 ×10-31Kg with opposite charge, whereas Proton is a sub atomic particle with mass 1.6726219 × 10-27Kg and positive Charge
- Atoms combine with each other to form compound atoms called Molecules
- John Dalton was the first scientist to use symbols for elements in a very specific sense.
- The most commonly used measurement for atomic radius is Nanometer – 0 x 10–9Metre and Angstrom A – 1.0 x 10-10Metre
- The relative Atomic Masses of all units have been measured w.r.t an atom of Carbon-12 which is equal to 1.66 × 10-24 g
- Hydrogen has the smallest atom and is considered to have an atomic mass – 1
- Molecules are defined as group of two or more atoms chemically bonded together, Atoms of same element or different elements group together to form a compound molecule.
- Compound formed between Atoms of Metals and Non-Metals have charged ions
| v Charge on the Ion – Negative | v Anion |
| v Charged on the Ion – Positive | v Cation |
- The combining capacity of an atom of an element with atoms of same element or different elements is called Valency of the element
| v Atomic Number | v Sum total of all protons present in the nucleus of an atom |
| v Atomic Mass | v Sum total of Protons and neutrons present in the nucleus of an Atom |
- The electrons present in the outermost shell of an atom are known as its valence electrons.
- Isotopes are atoms of same element having same Atomic Number but different Mass Numbers – (Hydrogen element has three Isotopes 1H1-Hydrogen, 2H1-Deuterium,3H1 – Tritium)
- Atoms of different elements with different Atomic Number but Same Mass Numbers are called Isobars. (Argon, Potassium, Calcium all have same Mass Numbers but different Atomic Number)
- Atoms of different elements, which have same number of neutrons but different atomic numbers, are called isotones.
- Avagadro Number: The number of Atoms present in 12g of Carbon of C-12 Isotope is 6.023 × 1023 Atoms
- 1 Mole of any substance will contain Avagadro number of Molecules or 6.023 × 1023 Atoms
- One Mole of any Gas at standard Atmospheric Pressure (STP) will have a volume of 22.4 Litres
- The electric neutrality of the atom is due to the presence of Equal number of Electrons and Protons in the atom
- The Spontaneous emission of radiation from the nucleus of an atom is a nuclear Phenomenon termed as Radioactivity
- Henry Becquerel first discovered radioactivity in 1896. The SI units to measure
- Radioactivity is Becquerel and unit of Becquerel is Second‑1(Second Inverse)
- The radiation dose absorbed by the human body is measured using the SI unit Gray or conventional unit RAD
- Carbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon.
- The most essential particle to continue the chain reaction in the fission of Uranium is Neutron.
Prefixes used in the SI System
| Prefix | Symbol | Multiplier |
| exa | E | 1018 |
| penta | P | 1015 |
| tera | T | 1012 |
| giga | G | 109 |
| mega | M | 106 |
| kilo | k | 103 |
| hecto | h | 102 |
| deka | da | 101 |
| deci | d | 10-1 |
| centi | c | 10-2 |
| milli | m | 10-3 |
| micro |  | 10-6 |
| nano | n | 10-9 |
| pico | p | 10-12 |
| femto | f | 10-15 |
| atto | a | 10-18 |
General Science – Chemistry PDF Notes for SSC CGL & RRB Exams, Matter and Its Nature General Science Notes, General Science Chemistry Notes in PDF,
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