Best ppt for projects. in this you will find all the information related to atoms, discovery of neutrons, electrons, nucleus, protons,etc.

1. STRUCTURE OF ATOMS

2. What are atoms ?????
An atom is the smallest constituent unit of ordinary matter that
has the properties of a chemical elements. Every solid, liquid, gas,
and plasma is composed of neutral or ionized atoms. Atoms are very
small; typical sizes are around 100 picometers .
Atoms are small enough that attempting to predict their behavior
using classical physics- as if they were billiard balls, for example-
gives noticeably incorrect predictions due to quantum effects.
Through the development of physics, atomic models have
incorporated quantum principles to better explain and predict the
behavior.

3. STRUCTURE OF ATOMS
An atom consists of electrons surrounding a nucleus that
contains protons and neutrons. Neutrons are neutral but, protons
and electrons are electrically charged. Protons have a relative
charge of +1, while electrons have relative charge of -1. The
number of protons in an atom is called atomic number. The
electron is by far the least massive of these particles at 9.11 X
10 -31 kg and size that is too small to be measured using available
techniques. Protons have about 1,836 that of the electron, at
1.6726 X 10-27
Neutrons have a free mass of 1839 times the mass of electron,
or
1.6929 X 10-27 kg, the heaviest of three constituent particles.

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Ernest Rutherford
discovered NUCLEUS in

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Ernest Rutherford
discovered PROTONS in

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J.J. Thomson
discovered ELECTRON in

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James Chadwick
discovered NEUTRON in

8. BOHR’S MODEL OF ATOM…..
Bohr atomic model, description of the structure of atoms, especially that of hydrogen,
proposed (1913) by Danish physicist
NEILS BOHR. The Bohr atomic model of the atom, a radical departure from earlier,
classical descriptions, was the first that incorporated quantum theory and was the
predecessor of wholly quantum mechanical models. The Bohr model and all of its
successors describe the properties of atomic electrons in terms of a set of allowed
values. Atoms absorb or emit radiations only when the electrons abruptly jumped
between allowed, or stationary, states. Direct experimental evidence for this existence
of such discrete states was obtained (1914) by the German – born physicists James
Franck and Gustav Hertz. Immediately before 1913, an atom Was thought of
consisting of a tiny positively charged heavy core, called a nucleus, surrounded by
light, planetary negative electrons revolving in circular orbit of arbitrary radii.
Bohr amended that view of motion of the planetary electrons to bring the model in
the line with the regular patterns of light emitted by real hydrogen atoms. By limiting
the orbiting electrons to a series of circular orbits having discrete radii, Bohr could
account for the series of discrete radii, Bohr could account for the series of discrete
wavelengths in the emission of spectrum of hydrogen. Light, he proposed, radiated
from hydrogen atoms only when an electron made a transition from an outer orbit to
one closer to the nucleus. The energy lost by the electron in the abrupt transition is
precisely the same as the energy the quantum of emitted light.

9. RADIOISOTOPES
Radioisotopes are radioactive isotopes of an element.
Different isotopes of the same element have the same
number of protons in their atomic nuclei but differing
number of neutrons. They can also be defined as atoms that
contain an unstable combination of neutrons and protons.
Radio isotopes have many useful applications. In medicine,
for example, cobalt-60 is extensively employed as radiation
source to arrest the development of cancer.
Other radioactive isotopes are used as trackers for
diagnostic purposes as well as in research on metabolic
processes. When a radioactive isotope is added in small
amounts to comparatively large quantities of the stable
element, it behaves exactly the same as the ordinary isotope
chemically; it can, however, be traced with a Geiger counter
or other detection device. Iodine-131 has proved effective in
treating hyperthyroidism. Another medically important
radioactive isotope is carbon-14, which is used in a breath
test to detect the ulcer-causing bacteria Heliobacter pylori.

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