History history Notes and pdf RRB RAILWAYS SSC UP SI

Notes on Buddhism and Jainism

Buddhism and Jainism are two branches of the Samana tradition that still exists today. Buddhism and Jainism originated from the prevailing pessimism of the time and both creeds had some common points.

Jainism and Buddhism had the largest number of followers among the mercantile class. Both Mahavira and Buddha preached their doctrines in the language of the people.

➤Buddhism :

• Buddhism was started by Gautam Buddha who was also known as Sakyamuni and Tathagata

• Gautam Buddha was born in the year 563 B.C at Lumbini near Kapilvastu district of Nepal on the day of the Poornima (full moon day)

• His childhood name was Siddhartha

•  His father’s name was king Suddhodhana who was the ruler of the Saka dynasty and the mother’s name was Mahamaya who was the princess of the Kosalan dynasty

• 7 days after the birth of Gautam Buddha, her mother died and he was brought up by his stepmother Mahaprajapati Gautami  who gave him the  title of Gautam

• In his childhood Gautam Buddha use to play with his horse named Kanthak

• At the age of 16 years Gautam Buddha was married with extremely beautiful Yasodhara and had a son named Rahula

• After seeing the sorrow of the world Gautam Buddha decided to leave the pleasures of the life and start living the life of the wanderer

• At the age of 29 years he left home in search of salvation or Nirvana and reached Vaishali where he became the disciple of Alara Klama but he was not convinced by the teachings of Alara Klama and he moved from there and became the disciple of Udraka Ramputra

• He wondered for 6 years and one day at Bodh Gaya under the Peepal tree (bodhi tree) he attained the Nirvana or Enlightenment at the age of 35 years

• Tapasso and Mallic became the first disciple of Gautam Buddha whereas Ananda was the most favorite disciple of Gautam Budddha

• Gautam Buddha delivered his first sermon at Sarnath on the topic “Dharmachakrapravartan” or Turning of the Wheel of Law

• In his last days of life he reached Vaishali where his disciple named Kunda fed him pork due to which he died at the age of 80 years in the year 483 B.C at Kushinagar district Deoria in the Malla republic. His death is known as Mahaparinirvana

➤Important events in the life of Buddha :






Lotus and Bull





Bodh Gaya

Bodhi Tree

Dharmachakra Pravartana






➤Doctrines of Buddhism :

• Four noble truths

1. Dukha – life is full of sorrow

2. Samyuda – there are causes for the sorrow

3. Nirodha – they can be stopped

4. Nirodha Gamini Pratipada – Path leading towards cessation of sorrow

• Eight-Fold Paths of Buddhism

1. Right observation

2. Right determination

3. Right exercise

4. Right action

5. Right speech

6. Right memory

7. Right meditation

8. Right livelihood

• Madhya Marga – to avoid the excess of both luxury and austerity

• Triratnas – Buddha, Dharma and Sangha

➤ Buddhist Literature :

The Buddhist literatures were written in the Pali language

• Vinay Pitaka

It deals with the laws of the Buddhist monasteries. It was recited by Uppali in the first Buddhist council in the year 483 B.C

• Sutta Pitaka

It is the collection of the Buddha’s sermons and it is divided in 5 parts

• Abhidhamma Pitaka

It deals with the life and the philosophy of the Buddha’s teachings

• Milindapanho

It deals with the conversation with the Greek king Menander and the Buddhist Monk Nagasena

• Tripitaka

It is the sacred book of the Buddhism

➤Buddhist Councils :

1. First Council

The first council was held in the year 483 B.C at Saptaparni caves near Rajgriha in Bihar under the chairmanship of king Ajatshatru, during the first council two Buddhist literatures were compiled Vinaya and Sutta Pitaka by Upali

2. Second Council

The second council was held in the year 383 B.C at Vaishali under the chairmanship of king Kalashoka

3. Third Council

The third council was held in the year 250 B.C at Patliputra under the chairmanship of king Ashoka the Great, during the third council Abhidhamma Pitaka was added and Buddhist holy book Tripitaka was compiled.

4. Fourth Council

The fourth council was held in the year 78 A.D at Kundalvan in Kashmir under the chairmanship of king Kanishka, during this council Hinayana and Mahayana were divided.

➤Types of Buddhist :

The Buddhism after the death of Gautam Buddha was divided into 3 parts

1. Hinayan

They believe in the real teachings of Gautam Buddha of attaining Nirvana. They do not believe in idol worship and Pali language was used in the Hinayana text

2. Mahayana

They believe that Nirvana is attained by the grace of Gautam Buddha and not by following his teachings. They believe in idol worship and Sanskrit was used in Mahayana text

3. Vajrayana

They believe that Nirvana is attained by the help of magical tricks or black magic.

➤Famous Monks at the time of Buddha :

• Ananda – constant companion of Buddha and most devoted disciple

• Anurddha – master of right mindfulness

• Mahakassapa – president of Buddhist council held at Rajagriha

• Moggallana – he had greatest super natural powers

• Sariputta – possessed the profound insight into the dhamma

• Upali – master of Vinaya

➤Famous Buddhist Scholars :

• Ashvagosha – contemporary of Kanishka, poet, dramatist, musician who wrote famous book Buddhacharita

• Nagarjuna – friend and contemporary  of Satavahana kings wrote the famous book Madhyamik Shastra

• Buddhagosha – pali scholar  who wrote “Visuddhimaga”

• Dinnaga – founder of Buddhist logic

➤Important Buddhist Gods and Goddess :

1. Buddha Shakyamuni – the historical Buddha

2. Buddha Maitreya – the future Buddha.

3. Avalokiteshavara – the Bodhisattva of Compassion

4. Manjushri – the bodhisattva of wisdom and literature.

5. Tara – a female Bodhisattva. She is considered a great protector that guards people against the eight major dangers in life

6. Padmasambhava – also called Guru Rinpoche, is the historically tangible founder of Tibetan Buddhism

➤Jainism :

• According to Jain tradition, there were 24 Tirthankaras. Rishabha was the first Tirthankara and Vardhaman Mahavira was the 24th Tirthankara.

• Mahavira was born in 540 BC Kundagrama near Vaishali, and left his home at the age of 30.

• At the age of 42, he attained the highest spiritual knowledge called Kevala-Jnana.

• As per Jainism way to Nirvana is also known as Three Ratnatraya involves Right faith, Right knowledge and Right conduct.

• Five carinal principles of Jainism are Ahimsa, Non-Lying, Non-Stealing, Non-Possession, and Brahmacharya. 

• Later divided into two sects: Swethembaras and Digambaras.

➤Five vows of Jainism :

• Ahimsa – non-violence

• Satya – do not speak a lie

• Asteya – do not steal

• Aparigraha – do not acquire property

• Brahmacharya – celibacy

➤Three main principles :

• Ahimsa

• Anekantavada

• Aparigraha

➤Triratna’s of Jainism :

• Right faith – Samayak Shradha

• Right Knowledge – Samayak Jnan

• Right Conduct – Samayak karma

➤Five types of knowledge :

• Mati jnana

• Shruta jnana

• Avadhi jnana

• Manahparayaya Jnana

• Keval Jnana

➤Jain council :

• 1st Council at Patliputra under the Patron of Chandragupta Maurya in 300 BC during which the 12 angas were compiled

• 2nd Council at Vallabhi in 512 AD during which the final compilation of 12 angas and 12 upangas was done

➤Sects :

• Shwetambars – Sthulabhadra – People who put on white robes. Those who stayed back in the North during the times of famine

• Digambars – Bhadrabahu – Exodus of monks to Deccan and South during the times of Magadhan famine. They have a naked attire

➤Jain Literature :

Jain literature used Prakrit, which is a common language of people than using Sanskrit. In this way, Jainism reached far and wide through people. The important literary works are

• 12 Angas

• 12 Upangas

• 10 Parikramas

• 6 Chhedsutras

• 4 Mulasutras

2 Sutra Grantas

• Part of Sangam literature is also attributed to Jain scholars.


History history Notes and pdf RRB RAILWAYS SSC UP SI

Notes on mauryan empire

History Notes and pdf RRB RAILWAYS SSC

Rise of maratha Empire

History Notes: Rise of Maratha Empire
➤Maratha Empire

• The geographical condition of Maharashtra helped in the rise of the Maratha empire.

• It’s an important episode of Indian history.

• Most of the region of Maharashtra had plateau region plateau also provided a good facility for guerilla-warfare to the Maratha.

• The rise of the Maratha empire was the result of the efforts of the entire Maratha people who on the basis of unity of their languages, literature, community, and homeland gave birth to Maratha nationalism and desired to create an independent state of their own.

• The saints of the Bhakti Movement in Maharashtra had also played an important role.
➤Chhatrapati Shivaji Maharaj

• Shivaji was born in 1627. In fort of Shivneri

• He was the son of Shahji Bhonsle and Jija Bai.

• Shivaji inherited the Jagir of Poona from his father in 1637.

• After the death of his guardian, Dadaji Kondadev, in 1647, he assumed full charge of his Jagir.

• His guru was Ramdas Samrath

• He conquered many Forts viz., Singh Garh/ Kondana (1643), Rohind and Chakan (1644-45), Toran (1646), Purandhar (1648), Rajgarh/ Raigarh (1656), Supa (1656), Panhala (1659).

• In 1657 Shivaji first confronted the Mughals, talking advantage of the Mughal invasion of Bijapur, he raided Ahamadnagar and plundered Junnar.

• In 1659-60, Afzal Khan was deputed by Adil Shah of Bijapur to punish Shivaji; but the later Afzal Khan was murdered by Shivaji in 1659. The famous ―baghnakh‖ episode is related with the death of Afzal Khan.

• In 1660, Shaista Khan, governor of Deccan, was deputed by Aurangzeb to check Marathas. Shivaji lost Poona, Kalyan and Chakan also suffered several defeats till he made a bold attack on Shaista Khan(1663) and plundered Surat (1664) and later Ahmadnagar.

• Raja Jai Singh of Amber and Diler Khan were then appointed by Aurangzeb to curb the rising power of Shivaji in 1665.

• Jai Singh succeeded in besieging Shivaji in the fort of Purandhar. Consequently the treaty of Purandhar (1665) was signed according to which Shivaji ceded some forts to the Mughals and paid a visit to the Mughal court at Agra.

• 1666, Shivaji visited Agra but there he was insulted.

• 1670, Shivaji captured most of the forts lost by the treaty of Purandhar.

• 1674 Shivaji was coroneted at capital Raigarh and assumed the title of Haindava Dharmodharak (Protector of Hinduism).

• After that Shivaji continued the struggle with Mughals and Siddis (Janjira). He conquest Karnataka during 1677-80.

• His last expedition was against Ginjee and Vellore.

➤Successors of Shivaji

  1. Shambhaji (1680-1689)-

• Sambhaji, the elder son of Shivaji, defeated Rajaram, the younger son of Shivaji, in the war of succession.

• He provided protection and support to Akbar II, the rebellious son of Aurangzeb.

• He was captured at Sangameswar by a Mughal noble and executed(killed).

  1. Rajaram (1689-1700)-

• He succeeded the throne with the help of the ministers at Rajgarh.

• He fled from Rajgarh to Jinji in 1689 due to a Mughal invasion in which Rajgarh was captured along with Sambhaji‘s wife and son (Shahu) by the Mughals.

• Rajaram died at Satara, which had become the capital after the fall of Jinji to Mughal in 1698.

• Rajaram created the new post of Pratinidhi, thus taking the total number of the minister to nine (Pratinidhi+Ashtapradhan).

  1. Tarabai(1700-1707)-

• Rajaram was succeeded by his minor son Shivaji II under the guardianship of his mother Tarabai.

• Tarabai continued the struggle with Mughals

  1. Shahu (1707-1749)-

• Shahu was released by the Mughal emperor Bahadur Shah.

• Tarabai‘s army was defeated by Shahu at the battle of Khed (1700) and Shahu occupied Satara.

• Shahu‘s reign saw the rise of Peshwas and the transformation of the Maratha kingdom into an empire based on the principle of the confederacy.

  1. Balaji Viswanath (1714-20)=The First Peshwa

• He began his carrier as a small revenue official and was given the title of Sena Karte (a marker of the army) by Shahu in 1708.

• Balaji became Peshwa in 1713 and made the post the most important and powerful as well as hereditary.

• He concluded an agreement with the Syed Brothers-King Maker (1719) by which the Mughal emperor Farrukhsiyar recognized Shahu as the king of the Swarajya.

  1. Baji Rao-I (1720-40)-

• Baji Rao, the eldest son of Balaji Viswanath, succeeded him as Peshwa at the young age of 20.

• He was considered the greatest exponent of guerrilla tactics after Shivaji and Maratha’s power reached its zenith under him.

• Under him, several Maratha families became prominent and got themselves entrenched in different parts of India.

• He conquered Bassein.

• Baji Rao-I also defeated the Nizam-ul-Mulk near Bhopal and concluded the treaty of Doraha Sarai by which he got Malwa and Bundelkhand from the latter (1738).

• Baji Rao-I said about Mughals: Let us strike at the trunk of the withering tree and the branches will fall of themselves‘

  1. Balaji Baji Rao(1740-61)-

• Popularly known as Nana Saheb, he succeeded his father at the age of 20.

• After the death of Shahu (1749), the management of all state affairs was left in his hands.

• In an agreement with the Mughal emperor Ahmad Shah, the Peshwa was to protect the Mughal empire from internal and external enemies (like Ahmad Shah Abdali) in return for Chauth (1752).

• The third battle of Panipat (Jan 14, 1761) resulted in the defeat of the Marathas by Ahmad Shah Abdali and the death of Viswas Rao & Sadashiv Rao Bhau. This event shocked the Peshwa Balaji Baji Rao and after six months he also died. This battle ended the Maratha power.

➤Anglo Maratha Wars:

  1. First Anglo -Maratha War (1775-1782)

The British fought in favour of Peshwaship to Raghunath Rao. The English (under Hastings) were defeated by the Marathas. They had to sign the Convention of Wadgaon in 1779, which was humiliating for the British. The English later signed the Treaty of Salbai in 1782 where they renounced their cause of Peshwaship for raghoba.

  1. Second Anglo – Maratha War (1803- 1806)

The Maratha Peshwa Baji rao II signed the Subsidiary Alliance Treaty of Bassein in 1802. Other Maratha chief who were part of Maratha confederacy, were not happy due to this arrangement. The Scindias of Gwalior began the war against the British but they were defeated by the British.

  1. Third Anglo – Maratha War (1817-1818)

It is also known as Pindari war. Lord Hastings was determined to proclaim British paramountcy in India. Hastings moved against Pindaris which transgressed the sovereignty of the Maratha chiefs and the war began. The Marathas were defeated.




India GDP growth rate

Geography Notes and pdf RRB RAILWAYS SSC

Continents and Oceans

The Earth – Shape and Size

Shape of the Earth

Pythagoras (572-500 B.C.), a Greek philosopher and mathematician, was among the first to suggest that the Earth was shaped like a globe.

The Earth is not flat

1.    If the Earth were a flat disc, then the rising Sun would have been seen at all places at the same time. But this does not happen. Places in the east see the rising Sun earlier.

2.    When a ship approaches land, its funnel or mast is seen first and then the hull. If the Earth had been flat, the whole ship would have been seen at the same time.

The Earth is a sphere

1.    The Earth is rarely oriented in the same position during successive eclipses but it always casts a circular shadow, thus proving that the Earth is a sphere. A sphere is the only solid body that will always cast a circular shadow.

2.    At the North Pole, the Pole Star can always be observed at 90 degrees in the sky, since the star lies in the line with the axis of the Earth.

3.    As one travels southwards, the angle of Pole Star decreases.

4.    At the Equator the angle becomes zero degree.

5.    This observation proves that the path of travel is an arc of a circle.

6.    The Sun, Moon and all the heavenly bodies appear to be spherical when viewed from different positions. It seems logical to conclude that the Earth is no exception.

7.    The photographs of the Earth taken from the space prove beyond any doubt that the Earth is a sphere.

The Earth as an Oblate Spheroid

1.    Refined measurements of the Earth have proved that the true form of the Earth resembles a sphere that has been compressed at the poles and made to bulge at the Equator. This form is known as an oblate spheroid.

2.    The various factors which make the earth suitable for

3.    life to evolve and survive are

4.    The earth has all the essential elements like carbon (in the form of C02), hydrogen (H2), nitrogen (N2) and oxygen (02) which act as building blocks for the origin of life.

5.    The earth is neither too hot nor too cold. It has the right temperature range for carrying out the life-sustaining chemical reactions.

6.    The earth has a lot of water in the form of lakes, rivers and oceans for the growth and survival of life.

7.    The earth has enough oxygen gas in its atmosphere for the survival of living beings through breathing.

8.    The earth has a protective blanket of ozone layer high up in its atmosphere to save life from harmful ultraviolet radiations coming from the sun.


Australia with New Zealand, Tasmania, New Guinea and the Pacific Islands (Micronesian, Melanesian and Polynesian Islands) is called Australasia by some geographers while some others call it “Oceania”, which includes proximate islands (Caribbean countries etc.).

Oceans on The Earth

There are four oceans. In order of their size, they are : Pacific Ocean, Atlantic Ocean, Indian Ocean and Arctic Ocean.

Pacific Ocean

1.    The explorer Ferdinand Magellan, who circumnavigated the Earth, named the ocean “Pacific” meaning calm or peaceful.

2.    The Pacific Ocean (Area : 166,240,000 sq. km.) is the largest ocean of the world.

3.    It is the deepest ocean with an average depth of 4,200 m.

4.    The Mariana Trench is the world’s deepest trench with a depth of 11,033 metres (36,201 feet).

5.    Most of the islands of this ocean are of volcanic or coral origin.

Atlantic Ocean

1.    The Atlantic Ocean (Area : 86,560,000 sq. km.) is the second largest ocean in the world

2.    Its name is derived from Atlas, a Titan (giant) in Greek mythology.

3.    The Atlantic Ocean has the longest coastline.

4.    The Atlantic Ocean is the busiest ocean for trade and commerce since its shipping routes connect the two most industrialized regions, namely Western Europe and N.E. United States of America.

5.    The Atlantic Ocean was formed millions of years ago when a rift opened up in the Gondwanaland and the continents of South America and Africa separated. The separation continues even today and the Atlantic Ocean is still widening.

6.    The continental islands of Newfoundland and British Isles are the major ones.

7.    Volcanic islands are fewer and they include those of Cuba, Jamaica and Puerto Rico. Iceland is the largest island of volcanic origin.

Indian Ocean

1.    The Indian Ocean (Area : 73,430,000 sq. km.) is the only ocean named after a country.

2.    The Indian Ocean is deeper than the Atlantic Ocean.

3.    It contains numerous continental islands, Madagascar and Sri Lanka are being the largest ones.

4.    Some of the islands of volcanic origin are those of Mauritius, Andaman and Nicobar, Seychelles, Maldives and Lakshadweep are of coral origin.

South Indian Ocean

1.    Warm currents : 1. South Equatorial 2. Mozambique 3. Madagascar 4. Agulhas.

2.    Cool Currents : 1. Antarctic drift 2. West Australian currents.

Arctic Ocean

1.    The Arctic Ocean (Area : 13,230,000 sq. km.) is the smallest of all the oceans.

2.    It lies within the Arctic Circle, hence the name Arctic Ocean.

3.    The North Pole lies in the middle of the Arctic Ocean.

4.    Most of the parts of Arctic Ocean remains frozen with thick ice for most of the days every year.

5.    It is the shallowest of all oceans, with an average depth of 1,500 m.

6.    It has the least salinity of all the oceans. It has a salinity of 20 unit per thousand.

Ocean Currents

1.    The flow of a large amount of water in a definite direction with a great intensity is known as Ocean Current.

2.    Ocean Currents are of two types-Hot and Cold.

Hot Currents

1.    The currents flowing from tropical zones of lower latitudes to higher temperate and sub polar zones are known as hot water currents.

Cold Currents

1.    The currents flowing from higher latitudes to lower latitudes are known as cold water currents.
2.    The only exception to the conduction of ocean currents is found in the Indian Ocean. The flow of currents changes here with a change in the direction of the Monsoon Winds. The hot currents flow towards cooler oceans and the cold currents flow towards the warmer oceans.


Notes and pdf Polity polity RRB RAILWAYS SSC

Notes on Salient Features of Indian Constitution

The Constitution of India is the longest, written constitution in the world, with 464 articles under 25 parts, 12 schedules, 5 appendices, and 122 amendments today. The Constitution of India is the lengthiest constitution in the world as no other constitution contains as many articles.

India is a Sovereign, Socialist, Secular, Democratic and Republic State

The Constitution declares India to be a Sovereign, Socialist, Secular, Democratic, Republic.

➤Sovereign means absolutely independent, it is not under the control of any other state.

➤Socialist involves a system which will endeavour to avoid concentration of wealth in a few hands and will assure its equitable distribution. It also implies that India is against exploitation in all forms and believes in economic justice to all its citizens.

➤Secular means there is no state religion in India. Every citizen is free to follow and practice the religion of his/her own choice. The state cannot discriminate among its citizens on the basis of religion.

➤Democratic means that the power of the government is vested in the hands of the people, people exercise this power through their elected representatives who are responsible to them. All citizens enjoy equal political rights.

➤Republic means that the head of the state is not a hereditary monarch.

➤Federal Government: The constitution provides for a federal form of government. In a federation, there are two governments- at the central level and at the state level. The powers of the government are divided between the central government and the state government.

➤Fundamental Rights & Fundamental Duties: Fundamental Rights and Fundamental Duties are the most important characteristics of the Constitution. Fundamental Rights are considered to be essential for the proper moral and material uplift of people. These rights are fundamental in the sense that any law passed by the legislature in the country would be declared as null and void if it is derogatory to the rights guaranteed by the constitution.

➤Parliamentary Government: Indian Constitution provides a parliamentary form of government. President is the nominal head of the state. The government is run by the Prime Minister and other members of the Council of Minister. The Council of Ministers is collectively responsible to the Parliament.

➤Partly rigid and partly flexible: The Constitution of India is neither wholly rigid nor wholly flexible. It is partly rigid and partly flexible.

• Certain provisions of the constitution can be amended by a simple majority in the Parliament.

• Certain provisions can be amended by a two-thirds majority of the Parliament and its ratification by at least fifty percent of states.

• The remaining provisions can be amended by the Parliament by the two-thirds majority.

➤Single Citizenship: In the federation, normally we have double citizenship. In the U.S.A every citizen of the United States of America is also a citizen of the state in which he or she resides. But the constitution of India provides single citizenship to every Indian.

➤Independent Judiciary: The Indian Constitution provides for an independent judiciary. The judiciary has been made independent of the Executive as well as the Legislature. The judges give impartial justice


List Of Diseases Caused By Virus, Bacteria, Protozoa And Worm

Disease caused by Viruses:

Chicken pox – It is caused by Varicella-zoster virus.

Small Pox – It is caused by Variola virus.

Common Cold -It is caused by Rhinovirus.

AIDS (Acquired Immunono Deficiency Syndrome) – It is caused by Human Immunodeficiency Virus (HIV).

Measles -It is caused by Measles virus.

Mumps -It is caused by Mumps virus.

Rabies – It is caused by Rabies virus (Rhabdoviridae family).

Dengue fever -It is caused by Dengue virus.

Viral encephalitis – It is an inflammation of the brain. It is caused by rabies virus, Herpes simplex, polio virus, measles virus, and JC virus.

Disease caused by Bacteria:

Whooping Cough – It is caused by a bacterium called Borde tella pertussis.

Diphtheria – It is caused by Coryne bacterium diphtheriae.

Cholera – It is caused by Vibrio cholerae.

Leprosy – It is caused by Mycobacterium leprae.

Pneumonia- It is caused by Streptococcus pneumoniae.

Tetanus – It is caused by Clostridium tetani.

Typhoid – It is caused by Salmonella typhi.

Tuberculosis – It is caused by Mycobacterium tuberculosis.

Plague – It is caused by Yersinia pestis.

Disease Caused by Protozoans: 

Malaria It is spread by Anopheles mosquitoes. The Plasmodium parasite that causes malaria is neither a virus nor a bacteria

Amoebic dysentery: It is caused by Entamoebahistolytica.

Sleeping sickness: It is caused by Trypanosomabrucei.

Kala azar It is caused by Leishmaniadonovani.

Disease Caused by Worms

Tapeworm: They are intestinal parasites. It cannot live on its own. It survives within the intestine of an animal including human.

Filariasis: It is caused by thread.

Pinworm: It is caused by small, thin, white roundworm called Enterobiusvermicularis


Notes on Atomic models and Quantum numbers

➤Atomic Models:

To show the arrangement of fundamental particles in an atom various models were proposed, some important models are as follows:

➤Dalton’s Atomic Theory:

The different assumptions of this theory are as follows;

• All matters are made up of atoms which are indivisible and indestructible.

• All the atoms of a given element have identical properties including identical mass.

• Atoms combine in small whole numbers to form the compound.

• Chemical reactions involve only combination, separation or rearrangement of atoms.

➤Thomson’s Atomic Model:

• Every atom consists of uniformly positively charge sphere having the radius in the order of 10-10 m  in which entire mass is uniformly distributed and negatively charges electrons are embedded randomly.

• Thomson uses the cathode ray tube to gives its atomic model.

• This model is known as the plum pudding model.

• According to him, negative charge particles are distributed in the atom and to balance this negative charge some positive charge particles also present in it.

• The atom as a whole is neutral.

➤Drawbacks of Thomson’s Atomic Model:

• It could not explain the origin of spectral series of hydrogen and other atoms.

• It could not explain large-angle scattering of alpha particles.

➤Rutherford’s Atomic Model:

• He fired a beam of the alpha particle on a sheet of gold to gives its model theory.

• The existence of nucleus was proved by Rutherford in his alpha particle scattering experiment.

• The entire positive charge and almost entire mass of the atom is concentrated at its centre in a very tiny region of the order of 10-15m, called the nucleus.

• The negatively charged electrons revolve around the nucleus in different orbits.

• The total positive charge on the nucleus is equal to the total negative charge on electron; therefore atom as overall is neutral.

• A nucleus consists of positively charged protons and electrically neutral neutrons.

➤Limitations of Rutherford’s Atomic models:

• According to Maxwell electromagnetic wave theory, an accelerated charged particle emits its energy in the form of electromagnetic waves. Therefore an electron must emit emits energy during its course of accelerated motion around the nucleus. Due to which the radius of its path will decrease gradually and ultimately it will fall in the nucleus.

➤Plank’s Quantum Theory:

 Planck gave a new revolutionary theory of radiation known as the quantum theory of radiation.

According to this theory

Radiant energy is not emitted or absorbed continuously but discontinuously in the form of small packets of energy known as photons (quanta).

The amount of energy associated with a quantum of radiation is proportional to the frequency of radiation.

Energy = hν

Where h is Planck’s constant

➤Bohr’s Model:

• Bohr’s model is based on the quantum physics i.e. quantization of energy

• This model is similar to the planetary model in which electron revolves around the nucleus in the specific orbit

• Bohr’s model is considered as the primitive hydrogen atom model

• Every orbit has a specific size and energy level.

• Smallest energy is found in the smallest orbit as energy is related to the size of the orbit.

• Electrons can move from one orbit to another by emitting or absorbing energies according to quantum mechanisms.

➤Heisenberg’s Uncertainty Principle:

• According to this theory, the position and velocity or momentum cannot be measured at a single instant.

• Heisenberg principle is not applicable to macroscopic objects

➤De-Broglie Concept:

• De Broglie states that electron has dual nature i.e. wave nature and particle nature

• Wavelength (l) of an electron is inversely proportional to its momentum (p)

        l=h/p=h/mv, where h is Planck’s constant


The electron has a definite energy characteristic of the orbit in which it is moving. These orbit or energy levels or shells therefore also known as stationary orbits.


Shell =K,L,M,N

The shell with n=1 is closest to the nucleus and an electron in this level has the lowest energy as it is closest to the positive charge of the nucleus.

➤Distribution of electrons in different orbits:

• It was suggested by Bohr and Burry and the rules that govern it are as follows:

• The maximum number of electrons present in a shell is given by the formula 2n2 where n=1,2,3 and 4 for K, L, M and N shells respectively.

• The maximum number of electrons that can be accommodated in the outermost orbit is 8.

• The shells are filled in a step-wise manner.

➤Electronic Configuration:

• It is the arrangement of electrons in various shells, subshells and orbitals in an atom.

• It is written as 2,8,8,18,32  

• The maximum number of the electron in a shell is given by 2n2

➤Filling or orbitals in Atoms:

The filling of electrons into orbitals of different atoms takes place according to the Aufbau Principle, Pauli Exclusion Principle and Hund’s rule of maximum multiplicity.

According to Aufbau principle in the ground state of an atom, electron enters the orbital of lowest energy first and subsequent electrons enter in the order of increasing energies.

The lower the value of (n+l) for an orbital, the lower is its energy.

here l is the azimuthal quantum number and n indicates the principle quantum number

If two orbitals have same (n+l) value, the orbital with the lower value of n has lower energy.

Hund’s rule of maximum multiplicity deals with the filling of electrons into the orbitals belonging to the same sub-shell. According to this rule, electron pairing will not take place in the orbital of the same energy until each orbital is first singly filled with parallel spin.

➤Quantum Numbers:

Each electron in an atom is characterised by a set of definite values of three quantum numbers n, l and m. In addition of these three numbers, fourth quantum numbers is also needed which specifies the spin of the electron.

1. Principal quantum number (n):

Determines the main energy level of the shell in which the electron is present.

The various values of n are 1, 2, 3 and 4 etc. also known as K, L, M and N etc. respectively, as the value of n increases the energy of electron also increases.

2. Azimuthal quantum number (l) determines the sub-level or sub-shell (s, p, d and f) in a given principal energy level or shell to which an electron belongs.

3. Magnetic quantum number (m) gives information about the orientation of the orbitals.

Spin quantum number(s) describe the spin orientation of the electron; the electron can spin only in two ways, i.e. clockwise or anticlockwise.

4. Pauli Exclusion Principle:

It states that no two electrons in an atom can have the same set of four quantum numbers.

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