Chemistry GK-Matter – SARKARI LIBRARY

Endothermic

Endothermic processes: Melting, Vaporization, Evaporation, Sublimation
An endothermic reaction is a chemical reaction that absorbs heat energy from its surroundings.
In endothermic reactions, the temperature of surroundings decreases.
Heat is written on the reactant side in an endothermic chemical equation.
The enthalpy change (ΔH) of an endothermic reaction is positive.
More energy is required to break bonds than the energy released in forming new bonds.
Endothermic reactions often feel cold to touch.
Photosynthesis is a classic example of an endothermic reaction.
Thermal decomposition reactions are usually endothermic in nature.
Endothermic reactions cannot continue without a constant energy supply.
Melting of ice is a physical endothermic process.
Evaporation of water is an endothermic change.
In endothermic reactions, products have higher energy than reactants.
Breaking of ionic or covalent bonds requires energy, making many such reactions endothermic.
Endothermic reactions are important in cooling processes.
Absorption of heat causes an increase in internal energy of the system.

Exothermic

Exothermic processes: Condensation, Freezing, Deposition
An exothermic reaction is a chemical reaction that releases heat energy to the surroundings.
In exothermic reactions, energy of products is less than energy of reactants.
Heat is given out during the reaction, so the surroundings become warmer.
The enthalpy change (ΔH) of an exothermic reaction is negative.
examples
- Combustion reactions
- Respiration in living organisms
- Formation of water from hydrogen and oxygen
- Burning of fuels like coal, petrol, and LPG is exothermic in nature.
- Neutralization reaction between an acid and a base is usually exothermic.
In exothermic reactions, bond energy released is greater than bond energy absorbed.
Exothermic reactions are often used in heating and energy production.
Thermite reaction is a highly exothermic reaction.
During an exothermic reaction, temperature of the reaction mixture increases.
Exothermic reactions help maintain body temperature in warm-blooded animals.
Most oxidation reactions are exothermic.

Deposition

Deposition is the process in which a gas directly changes into solid.
It occurs due to loss of heat.
It is the reverse of sublimation.
Example: Frost formation.
Snow formation in clouds involves deposition.

Sublimation

Sublimation is the process in which a solid directly changes into gas without becoming liquid.
It occurs due to absorption of heat.
Example substances: Camphor, Naphthalene, Ammonium chloride, Dry ice.
Used for separating sublimable substances in chemistry.

Freezing

Freezing is the process of liquid changing into solid.
It occurs at a fixed temperature called freezing point.
Heat is released during freezing.
Example: Water → Ice at 0°C.
Freezing point of a substance is usually equal to its melting point.

Condensation

Condensation is the process of gas changing into liquid.
It occurs due to loss of heat (exothermic process).
Example: Steam → Water.
Dew formation is an example of condensation.
Condensation is the reverse of vaporization.

Evaporation

Evaporation is the slow conversion of liquid into vapor at any temperature.
It occurs only from the surface of the liquid.
It causes cooling effect.
Rate of evaporation increases with temperature, surface area, wind speed, and low humidity.
Example: Drying of wet clothes.

Melting

Melting is the process in which a solid changes into a liquid.
It occurs at a fixed temperature called melting point.
Heat is absorbed during melting (endothermic process).
Example: Ice → Water at 0°C.
During melting, temperature remains constant until the solid fully melts.

Vaporization

Vaporization is the process of liquid changing into gas.
It requires absorption of heat energy.
It occurs at a specific temperature called boiling point.
Example: Water → Steam at 100°C (at 1 atm pressure).
Vaporization is a fast process.

fermions

Fermions are fundamental particles that follow Fermi–Dirac statistics.
They are named after physicist Enrico Fermi.
Fermions have half-integer spin (±1/2, ±3/2, etc.).
All matter particles are fermions.
Fermions obey the Pauli Exclusion Principle.
According to the Pauli principle, no two identical fermions can occupy the same quantum state.
Electrons, protons, and neutrons are fermions.
Fermions are divided into leptons and quarks.
Electrons, muons, and neutrinos are leptons.
Fermions are the building blocks of atoms.
The structure of atoms and periodic table is due to fermions.
Fermions have antisymmetric wave functions.
Due to the exclusion principle, fermions create degeneracy pressure.
White dwarfs and neutron stars exist because of fermion degeneracy pressure.
Fermions contrast with bosons, which have integer spin.
Fermions cannot occupy the same space at the same time (quantum mechanically).
All stable matter in the universe is made of fermions.
Fermions are essential for chemistry, electricity, and solid-state physics.

boson

Bosons are particles that follow Bose–Einstein statistics.
The term boson is named after Indian physicist Satyendra Nath Bose.
Bosons have integer spin (0, 1, 2, …).
Unlike fermions, multiple bosons can occupy the same quantum state.
Bosons are responsible for carrying forces in nature.
Bosons are also called force carrier particles.
Photons are bosons that mediate the electromagnetic force.
Gluons are bosons responsible for the strong nuclear force.
Graviton (theoretical) is a boson associated with gravity.
Higgs boson gives mass to elementary particles.
The Higgs boson was discovered in 2012 at CERN.
Bosons can move at the speed of light if they are massless.

Satyendra Nath Bose

Indian physicist best known for his work in quantum mechanics.
He was born on 1 January 1894 in Kolkata, West Bengal.
He died on 4 February 1974.
He developed Bose–Einstein statistics in 1924.
His research paper was sent to Albert Einstein, who translated it into German and helped publish it.
The collaboration led to the prediction of Bose–Einstein Condensate.
The particle boson is named after Satyendra Nath Bose.
Bosons follow Bose–Einstein statistics, unlike fermions.
Bose was never awarded the Nobel Prize, despite his groundbreaking work.
He was awarded Padma Vibhushan in 1954.
SN Bose National Centre for Basic Sciences – Founded: 1986, Kolkata, West Bengal

Solid

Definite shape & volume.
Particles vibrate in fixed positions.
Particles in a solid are closely packed with strong intermolecular forces.
Solids have minimum kinetic energy among the three states of matter.
Solids are almost incompressible.
Solids have high density compared to liquids and gases.
Solids can resist deformation due to strong binding forces.
Diffusion in solids is very slow and usually negligible.
Solids have fixed positions of particles.
Solids expand on heating and contract on cooling.
- Thermal expansion occurs in all solids when heated.
Iron, copper, and gold are metallic solids.
Diamond and graphite are covalent solids.
Sodium chloride is an ionic solid.
Elastic limit is the maximum stress a solid can withstand without permanent deformation.
Hooke’s Law: Stress is proportional to strain within elastic limit.
property
- Plasticity- d undergoes permanent deformation.
- Ductility – drawn into wires.
- Malleability- beaten into thin sheets.
Types of Solids
- Crystalline solids have a regular and repeating arrangement of particles.
  - Crystalline solids have a definite melting point.
- Amorphous solids have an irregular arrangement of particles.
  - Amorphous solids do not have a definite melting point.
  - Glass is an example of an amorphous solid.

Liquid

Definite volume, no definite shape.
liquids take the shape of the container in which they are kept.
The intermolecular force in liquids is weaker than solids but stronger than gases.
Liquids are almost incompressible compared to gases.
Liquids can flow, hence they are called fluids.
- Viscosity = resistance to flow.
- The viscosity of liquids decreases with increase in temperature.
Water has maximum density at 4°C.
Liquids expand on heating and contract on cooling.
Surface tension is the tendency of liquid surfaces to minimize surface area.
- Surface tension decreases with increase in temperature.
Liquids show capillary action due to surface tension and adhesion.
Mercury does not wet glass due to strong cohesive force.
Liquids exert pressure in all directions.
Liquid pressure increases with depth.
Liquids are measured in liters or cubic meters.
Pascal’s Law is applicable to liquids at rest.
Diffusion in liquids is slower than gases but faster than solids.
Liquids can exist in different densities depending on temperature.
The boiling point of a liquid decreases with decrease in pressure.

Gas

No definite shape or volume.
Negligible intermolecular forces.
Particles move randomly at high speeds.

Plasma

Plasma: Ionized gas (e.g., stars, neon signs).
Good conductor of electricity.
Plasma is known as the fourth state of matter.
Plasma consists of free electrons and positively charged ions.
It is formed when gas is heated to very high temperatures or subjected to strong electric fields.
Plasma is an electrically conducting state of matter.
Plasma does not have a fixed shape or volume, similar to gases.
Plasma responds strongly to electric and magnetic fields.
Sun and stars are made mostly of plasma.
About 99% of visible matter in the universe exists in plasma state.
Plasma is created when atoms lose electrons due to high energy.
Lightning is a natural example of plasma.
Aurora Borealis (Northern Lights) is caused by plasma interactions in Earth’s atmosphere.
Neon signs and fluorescent lamps work on plasma principle.
Plasma is sometimes called ionized gas.
Plasma shows collective behavior due to long-range electromagnetic forces.
Plasma was first identified as a distinct state by Irving Langmuir.
Plasma is used in plasma cutting and welding industries.
Fusion reactions, used in stars, occur in plasma state.
Plasma is used in semiconductor manufacturing.
Plasma can exist at very high temperatures, but also as low-temperature plasma.
Plasma state is important in astrophysics and space science.

Einstein

Albert Einstein was born on 14 March 1879 in Ulm, Germany.
known for
- Theory of Relativity.
- The Special Theory of Relativity was published in 1905.
- The General Theory of Relativity was published in 1915.
He gave the famous equation E = mc².
Einstein won the Nobel Prize in Physics in 1921.
- He received the Nobel Prize for explaining the Photoelectric Effect.
The year 1905 is called Einstein’s “Miracle Year.”
Einstein worked as a patent clerk in Switzerland.
He later became a German citizen, then a Swiss, and finally an American citizen.
He migrated to the USA in 1933.
Einstein worked at Princeton University in the USA.
He opposed Nazism and nuclear weapons.
Albert Einstein died on 18 April 1955 in Princeton, New Jersey, USA.
His brain was preserved for scientific research.