Definition of Elements and atom Origin of Universe Theories of origin of Solar system and Earth Chemical Composition of Planets Chemical Composition of Earth Chemical composition of Meteorites Abundance of Elements

1. ORIGIN AND ABUNDANCE OF ELEMENTS
IN THE SOLAR SYSTEM AND IN THE
EARTH AND ITS CONSTITUENTS
Akshay D. Raut
M.Sc. Sem III
Department of Earth And
Environmental Science

2. ELEMENTS
Elements are the simplest pure substances
 Made of only one kind of material, has
definite properties, and is the same all
throughout.
 They cannot be broken down into simpler
substances without losing their identity.

3. ELEMENTS AND ATOMS
• The smallest particle of an element that
has the properties of that element is called
an atom.
• Atoms of same element are alike; atoms of
different elements are different.

4. ORIGIN OF UNIVERSE
BIG BANG THEORY
• A theory of Astronomy: the Universe originated 13.8
billions of years ago in an explosion from a Singularity.
• Singularity- A single point of nearly infinite energy
density- where all known space was compressed into an
infinitely small mass.
• In the first second after the universe began, the
surrounding temperature was about 5.5 billion Celsius,
according to NASA.
• After the Big Bang only the lightest elements were formed
– Hydrogen and Helium along with trace amount of
Lithium and Beryllium.

5. ORIGIN OF THE SOLAR SYSTEM AND THE EARTH
• The earliest accounts of how the sun, the Earth
and the rest of the solar system were formed are
to be found in early myths, legends and religious
texts. None of these can be considered a serious
scientific account.
• The earliest scientific attempts to explain the
origin of solar system invoked collision or
condensation from a gas cloud.

6. Continued….
Theories of Origin of Solar System -
Evolutionary Theories – Suggests that planets are formed
during the evolution of the Sun.
Ex. Nebular Hypothesis
Catastrophic Theories – Suggests that planets are formed
by some special accident or catastrophe, such as close
approach of two stars or collision of two stars.
Ex. Planetisimal Hypothesis, Gaseous Tidal Hypothesis.

7. 1: NEBULAR HYPOTHESIS( BY KANT AND LAPLACE)

8. 2: PLANETESIMAL HYPOTHESIS
(CHAMBERLIN AND MOULTON)

9. ORIGIN OF ELEMENTS IN THE SOLAR SYSTEM
AND THE EARTH
• Equilibrium Theory - Frozen thermodynamic equilibrium
between atomic nuclei at some high temperature and
density.
• When the universe was first created, essentially all matter
was in the form of two elements- hydrogen and helium
with relative abundance ( by weight ) of 75% and 25%
respectively.
• Further expansion and cooling allowed the neutrons and
some of the protons to fuse to helium nuclei. During
condensation period to today – Hydrogen (73%), Helium
(25%) and other elements (2%).

10. Continued…..
Elemental matter started with hydrogen, which formed the
primitive matter from which stars were made.
• Hydrogen burning to produce helium.
• Two atoms of hydrogen are combined in a series of steps to
create helium-4.
These two reactions account for 85% of the Sun’s
energy. The remaining 15% comes from reactions that produce
the elements beryllium and lithium.
The energy from these nuclear reactions is emitted in
various forms of radiation. Energised particles such as
neutrinos and protons are released and it is then make up the
solar wind.
This energy streams warms the planet, drives weather
and provides energy for life on the Earth.

11. Dying Stars
When a star’s core run out of hydrogen, the star begins to
die out. The dying star expands into a red giant, and this now
begins to manufacture carbon atoms by fusing helium atoms.
Example of element making in helium burning reactions:
• 3 4He= 12C
• 12C+4He= 16O
• 16O+4He= 20Ne
• 20Ne+4He= 24Mg

12. Man-Made Elements
Only 90 of the 116 known elements occur naturally.
The remaining 26 found in the development of
nuclear power plants and machines known as
particle accelerators.
For Ex- By allowing fast neutrons to collide with the
common isotope of uranium known as U-238 in a
nuclear reactor, the new element plutonium was
made.

13. CHEMICAL COMPOSITION OF SOLAR
ATMOSPHERE
Element Name Abundance %
Hydrogen 73
Helium 25
Oxygen 0.80
Carbon 0.36
Iron 0.12
Other Elements 0.72

14. CHEMICAL COMPOSITION OF PLANETS
Mercury – No atmosphere and density similar to the Earth.
Composition of Mercury is probably high in iron.
Venus – Size and mass of Venus suggests its composition is
probably much like that of Earth. It has very dense
atmosphere, consisting entirely of CO2 and Nitrogen.
Mars - Clouds and dust storms have been observed on the
face of Mars. Polar frost caps form in winter and disappear
in summer. These caps appear to be formed thin layer of
H2O ice with some solid CO2. Much of surface of Mars has a
reddish or orange coloration, which may be due to iron
oxide coating. The size and mass indicate a bulk composition
similar to that of Earth. Oblateness of Mars and lack of
magnetic field suggests that it does not have fluid core.

15. Continued…..
Jupiter, Saturn, Uranus, Neptune –
Interior similar to that of Earth, but covered with great
thickness of ice and condensed gases and have atmosphere
containing hydrogen, helium, nitrogen, methane and
ammonia.
Ring of Saturn probably consist of ice particles.
The albedos and densities of some of the satellites of these
planets suggests that they consist largely of ice.

16. CHEMICAL COMPOSITION OF THE EARTH
Sl. No Elements By Weight (%)
1 Oxygen 46.60
2 Silicon 27.72
3 Aluminium 8.13
4 Iron 5.00
5 Calcium 3.63
6 Sodium 2.83
7 Potassium 2.59
8 Magnesium 2.09
9 Others 1.41

17. CHEMICAL COMPOSITION OF THE EARTH

18. Comet
An object that moves around then sun, usually
at a great distance from it, that is seen on rare
occasions from the Earth as a bright line in the sky.
They are composed of rock, dust, water ice and
frozen gases such as co, co2, methane and ammonia

19. COMPOSITION OF METEORITES
• On the basis of composition, Meteorites can be classified
as follows
1. Siderites or Irons ( Average 98% metal)
2. Siderolites and Stony irons ( Average 50% metal
and 50% Silicates )
3. Aerolites or Stones
a)Chondrites
b) Achondrites

20. ABUNDANCE OF ELEMENTS
• The abundances show a rapid exponential decrease for
elements of lower atomic numbers ( to about atomic
number 40), followed by almost constant value for the
heavier value for the heavier elements.
• Elements of even atomic number are more abundant than
those of odd atomic numbers on either side.
• The relative abundances for elements of higher atomic
number than nickel vary less than those for elements of
lower atomic number.
• Only 10 elements – H, He, C, N, O, Ne, Mg, Si, and Fe, all
with atomic numbers than 27.
• There is pronounced abundance peak at atomic number
26 and smaller peaks at several other heavier atomic
numbers.