The document summarizes key concepts about the structure of the atom. It discusses the three main subatomic particles - electrons, protons, and neutrons. It describes early atomic models proposed by Thomson, Rutherford, and Bohr. Key points of each model are provided. The document also discusses concepts like the distribution of electrons in shells, valency, atomic number, mass number, isotopes, and isobars. In summary, it provides an overview of the historical development of atomic structure and defines important atomic terms.
This pdf is written to describe structure of atom for school students of grades 9 to 10. In this the basics of atomic structure has been described. Starting from Dalton's atomic model to Rutherford's scatering of alpha particles, JJ Thomson and Bohr's models with photos.
Students can download and use it for studying atomic structure.
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Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
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This pdf is written to describe structure of atom for school students of grades 9 to 10. In this the basics of atomic structure has been described. Starting from Dalton's atomic model to Rutherford's scatering of alpha particles, JJ Thomson and Bohr's models with photos.
Students can download and use it for studying atomic structure.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
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The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
2. STRUCTURE OF THE
ATOM-
a) Charged particles in matter :-
• Atoms have three types of sub atomic particles. They are electrons, protons and neutrons.
• Electrons are negatively charged (e-), protons are positively charged (p+) and neutrons have no charge (n).
• The mass of an electron is 1/2000 the mass of a hydrogen atom. The mass of a proton is equal to the mass of a
hydrogen atom and is taken as 1 unit. The mass of a neutron is equal to the mass of a hydrogen atom and is
and is taken as 1 unit.
b) Discovery of sub atomic particles :-
• In 1900, J.J.Thomson discovered the presence of the negatively charged particles called electrons in theatom.
• In 1886, E.Goldstein discovered new radiations in gas discharge and called them canal rays. These rays were
positively charged. This later led to the discovery of the positively charged particles called protons in the atom.
• In 1932 Chadwick discovered the presence of particles having no charge in the atom called neutrons.
3. THOMSON’S MODEL OF AN ATOM :-
According to Thomson an atom is similar to a Christmas
pudding. The pudding had positive charge and the
electrons having negative charge were like plums on the
pudding.
• He proposed that :-
• i) An atom consists of a positively charged sphere and
the electrons are
• embedded in it.
• ii) The negative and positive charges are equal in
magnitude So the atom as a whole is electrically
neutral.
4. RUTHERFORD’S MODEL OF AN
ATOM :-
Rutherford’s alpha scattering experiment :-
• Rutherford allowed a beam of fast moving alpha
particles ( α –
• particles) having positive charge to fall on a thin
gold foil. He observed that :-
• i) Most of the α – particles passed straight
through the gold foil.
• ii) Some of the α – particles were slightly deflected
by small angles.
• iii) Very few α – particles appeared to rebound.
5. DEFECTS OF RUTHERFORD’S MODEL OF THE
ATOM :-
• Any particle in a circular orbit
would undergo acceleration and
during acceleration the charged
particle would radiate energy. So
the revolving electrons would lose
energy and fall into the nucleus
and the atom would be unstable.
We know that atoms are stable.
6. BOHR’S MODEL OF AN
ATOM :-
i) An atom has a positively charged nucleus at its
center and most of
the mass of the atom is in the nucleus.
ii) The electrons revolve around the nucleus in special
orbits called
discrete orbits.
iii) These orbits are called shells or energy levels and
are represented
by the letters K, L, M, N etc. or numbered as 1, 2, 3,
4, etc.
iv) While revolving in the discrete orbits the electrons
do not radiate energy.
Shells or energy
levels in an atom
7. DISTRIBUTION OF ELECTRONS IN DIFFERENT
SHELLS :-
• The distribution of electrons in the different shells was suggested by Bhor and Bury.
The following are the rules for filling electrons in the different shells.
• i) The maximum number of electrons in a shell is given by
• the formula 2n2 where n is the number of the shell 1, 2, 3 etc.
• First shell or K shell can have = 2n2 = 2 x 12 = 2x1x1 = 2 electrons
• Second shell or L shell can have = 2n2 = 2 x 22 = 2x2x2 = 8 electrons
• Third shell or M shell can have = 2n2 = 2 x 32 = 2x3x3 = 18 electrons
• Fourth shell or N shell can have = 2n2 = 2 x 42 = 2x4x4 = 32 electrons and so on.
8. ii) The maximum number of electrons that can be filled in
the outermost shell is 8.
iii) Electrons cannot be filled in a shell unless the inner
shells are filled.
10. VALENCY :-
Valency is the combining capacity of an atom of an element.
• The electrons present in the outermost shell of an atom are called valence
electrons.
• If an atom’s outermost shell is completely filled, they are inert or least
reactive and their combining capacity or valency is zero.
• Of the inert elements Helium atom has 2 electrons in the outermost shell
and the atoms of other elements have 8 electrons in their outermost shell.
Atoms having 8 electrons in their outermost shell is having octet
configuration and are stable.
11. If an atom’s outermost shell is not completely filled it is not stable. It will try to attain stability
by losing, gaining or sharing electrons with other atoms to attain octet configuration.
The number of electrons lost, gained or shared by an atom to attain octet configuration is the
combining capacity or valency of the element
Eg :- Hydrogen, Lithium, Sodium atoms can easily lose 1 electron and become stable. So their
valency is 1. Magnesium can easily lose 2 electrons. So its valency is 2. Aluminiun can easily lose 3
electrons. So its valency is 3. Carbon shares 4 electrons. So its valency is 4.
Fluorine can easily gain 1 electron and become stable. So its valency is 1. Oxygen can
easily gain 2 electrons. So its valency is 2. Nitrogen can easily gain 3 electrons. So its valency is 3.
12. ATOMIC NUMBER AND MASS NUMBER :-
Atomic number (Z) :-
The atomic number of an element is the number of protons present in the
nucleus of the atom of the element.
All the atoms of an element have the same atomic number.
Eg :- Hydrogen – Atomic number = 1 (1 proton)
Helium - Atomic number = 2 (2 protons)
Lithium - Atomic number = 3 (3 protons)
13. The mass number of an element is the sum of the number of protons and
neutrons (nucleons) present in the nucleus of an atom of the element.
The mass of an atom is mainly the mass of the protons and neutrons in the nucleus of the
atom.
Eg :- Carbon – Mass number = 12 (6 protons + 6 neutrons) Mass = 12u
Aluminium – Mass number = 27 (13 protons + 14 neutrons) Mass = 27u
Sulphur – Mass number = 32 (16 protons + 16 neutrons) Mass = 32u
In the notation of an atom the Mass number
atomic number and mass number Eg :- 14/7 N
are written as :- Atomic number
14. ISOTOPES
:-
Isotopes are atoms of the same element having the same atomic numbers but different mass
numbers.
Eg :- Hydrogen has three isotopes. They are Protium, Deuterium (D) and Tritium (T).
H H H
Protium Deuterium Tritium
Carbon has two isotopes. They are :-
C C
Chlorine has two isotopes They are :-
Cl Cl
15. ISOBARS
:-
Isobars are atoms of different elements having different atomic numbers but same
mass numbers.
These pairs of elements have the same number of nucleons.
Eg :- Calcium (Ca) – atomic number - 20 and Argon (Ar) – atomic number 18
have different atomic numbers but have the same mass numbers – 40.
Iron (Fe) and Nickel (Ni) have different atomic numbers but have the same atomic mass
numbers – 58.