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CHEMISTRY OF THE ELEMENTS

CHEMISTRY OF THE ELEMENTS. E lements in the U niverse and the W orld. Scientists believe that the universe began forming in an explosion with a tremendous release of energy known as the “ Big Bang .” The universe has been expanding ever since. The Big Bang Theory….

demetrius-price
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CHEMISTRY OF THE ELEMENTS

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  1. CHEMISTRY OF THE ELEMENTS

  2. Elements in the Universe and the World • Scientists believe that the universe began forming in an explosion with a tremendous release of energy known as the “Big Bang.” • The universe has been expanding ever since.

  3. The Big Bang Theory… • Matter and energy were concentrated in a very small volume and about 13.7 billion years ago (13,700,000,000 yrs) • Explosion was so powerful that space itself was propelled outwards almost instantaneously • 200 Million years later, the first stars formed • Universe is still expanding today

  4. Evidence forBig Bang • Observation of galaxies flying away from us in all directions. • Remnant (kalıntı) of the Big Bang known as the Cosmic Microwave Background Radiation. • Observed abundance of light elements produced in the Big Bang matches the predictions.

  5. Doppler Effect • The Doppler effect says that things moving away from you look redder than they would if they weren’t moving. • Things moving towards you look more blue.

  6. Formation and Expansion of the Universe

  7. 4 Fundamental forces in physics. Gravity Weak (holds neutron together): Note that free neutron is not stable n -> p + e + νe Electromagnetic (holds atoms together) Strong (holds nuclei)

  8. When temperature and energy density in Universe decrease, nuclei become stable. • Then as Universe gets colder atoms become stable and electromagnetic radiation does not interact with matter any more. • Remnant electromagnetic radiation from time of decoupling is cosmic background radiation.

  9. Summary of Formation of Elements via Big Bang • Up to 10–43 seconds after the Big Bang -Planck Epoch: The temperature is high enough that the four fundamental forces — electromagnetism, gravitation, weak nuclear interaction, and strongnuclear interaction —are all unified in one fundamental force. • 10-43seconds to 10-32seconds - Grand unification epoch: The grand unification epoch begins when gravitation separates from the other forces.Abnormal inflation stage.Universe expanded to an orange size.We can talk about the existence of fundemental particles quarks,leptons and gluons.

  10. Summary of Formation of Elements via Big Bang • 10-32seconds to 10-6seconds-Electroweak epoch:The Electroweak epoch begins 10–32 seconds after the Big Bang, when the temperature of the universe is low enough (1027ºC ) to separate the strong force from the electroweak force (the name for the unified forces of electromagnetism and the weak interaction).Pre inflation stage. Due to expansion temperature dropped to 1027ºC universe is still too hot so we can talk about a soup of the existence of electrons,quarks and other fundemental particles.

  11. Summary of Formation of Elements via Big Bang • 10-6.seconds-Quark Epoch:Afterelectroweak symmetry breaking, at the end of the electroweak epoch, rapid cooling stage started and temperature dropped to 1013ºC. Protons and neutrons are formed from quarks. But at this stage most of the universe is still in the form of photons. Collisions of these high energy photons were producing electon and positron couples and also the reverse of this process called annihilation. At this stage neutrons decayed to protons,electrons and antineutrinos: or Due to this reaction the first hydrogen nucleide formed and then deuterium nucleides also formed.But they decomposed by collisions due to unstability.

  12. Summary of Formation of Elements via Big Bang • 3 minutes 2.second: The ratio of protons to neutrons was about 7. • 3 minutes 46.second: Due to decrease in temperature the stability of deuterium ( 2H or D) nuclides increased.Almost all of the produced neutrons combined with protons to produce deuterium: The high abundance of hydrogen in universe can be explained by the greater reverse reaction rate of the above reaction. The produced deuteriums first fuses with protons to form 3He and then capture a neutron to form 4He nuclides or the produced deuteriums captures a neutron to produce tritium 3H first and then fuses with proton to form 4He nuclides.

  13. Summary of Formation of Elements via Big Bang At this stage the percentage abundances by mass of 1H and 4He were 75% and 25%. Some of the 2H nuclides combined with 4He form lithium,lithium-6( 6Li ) nuclides. Some of the 4He nuclides fuse with 3He or 4He to form berilium-7( 7Be )and berilium-8 ( 8Be ) nuclides.Due to instability , these berillium nuclides decayed.Due to very fast cooling of universe, the nuclides heavier than lithium cannot be formed at this stage.

  14. Summary of Formation of Elements via Big Bang • 300 000 years after Big Bang: Temperature decreased to 10 000 ºC. Electrons,protons and neutrons combine to form ATOMS. According to Big Bang Theory the nuclear processes in first fast inflation and cooling minutes Light Elements (hydrogen,helium and lithium) formed. The theoretical calculations about the percentage abundances by mass of hydrogen and helium in universe fits with the percentage abundances of them produced after Big Bang and remaining today.

  15. Star Formation Eventually the universe cooled and atoms formed. With the help of gravity these atoms (mostly hydrogen) clumped together to form stars.

  16. Formation of Heavy Elements • 1 billion year after the Big Bang: The temperature of universe decreased to -200 ºC. Due to gravitational forces between hydrogen and helium gases giant clouds formed.These giant clouds formed galaxies and smaller clouds formed stars which are ten or more than hundered times greater than our sun. • In the first generation of stars, hydogen nuclides fused to form helium at high temperature and pressure conditions.But the first stars disintegrated into smaller parts via very strong explosions. By the help of emitted energy and produced high pressure due to these explosions, elements heavier than hydrogen and helium formed.But the amount of heavier elements formed by this way was very small. • Then, second generation stars formed and since they had heavy elements in a very small extent their core temperatures reached to more than 108 ºC. And this temperature satisfied the necessary conditions for the formation of a series of nuclear fusion reactions.When the temperature at the core of these second generation stars reached to 108 ºK, three helium nuclides combined to form cabon nuclides.Since carbon nuclides formed are heavy, they move towards to inner shells.Cabon nuclides fuse with helium nuclides to form oxygen:

  17. Carbon and Oxygen We need carbon and oxygen to live. (Carbon dioxide, carbohydrates) The nuclear energy levels determine the rate of production of carbon and oxygen. These levels have been carefully tuned so that both carbon and oxygen are abundant. + He He Be (Beryllium) Be + He C (Carbon) C O (Oxygen) + He Carbon C + He Be + He Oxygen

  18. Thermonuclear Combustion Reactions • Energy evolves when light elements form heavy elements by thermonuclear fusion reactions. • The energy content of nuclear rections are very high compared to chemical reactions. • Nuclear fusion reactions are also called thermonuclear combustion reactions. • Do not confuse thermonuclear combustion reactions with chemical combustion (oxidation) reactions. • Thermonuclear combustion reactions are complex fusion reactions involve hydrogen and helium nucleides catalyzed by carbon.

  19. Nuclear Binding Energy • Elements having atomic number 26 (iron,26Fe) can be formed in the stars and they are the products of thermonuclear fusion reactions. • Elemets heavier than iron cannot be formed thermonuclear fusion reactions.This can related with the extra nuclear stability of 26Fe.

  20. Formation of Heavy Elements • Due to these thermonuclear combustion reactions Stars have onion-skin like shells. The exact structure depends on the mass of the star. • For large and old stars the elements formed moving inwards from lighter to heavier:

  21. Forming Elements from Nuclear Fusion Scientists believe that the lightest elements, hydrogen, helium, lithium, and beryllium were created in the first few minutes of the Big Bang. Stars have the capability, through their nuclear fusion process, to create lighter elements (from helium up to iron). Remember, stellar nebula start with large amounts of hydrogen. The fusion of lighter elements will continue until iron is created by the star. Fusing iron into heavier elements actually requires an input of energy. At this stage of their life, stars do not have the additional energy to fuel the fusion process and they collapse. A star similar to the size and mass of our Sun (left) and a star about 100 times the size of our Sun (right).

  22. Formation of the Elements • Cosmological Nucleosynthesis: • Most H and He formed shortly (few seconds) after the Big Bang, when T cooled to 1 billion degrees • (H and He make up most of the universe!) • Stellar Nucleosynthesis: • Most heavier elements (metals) form either in Red Giants or Supernovae by nuclear fusion • (but without these there would be no life!)

  23. Stellar Nucleosynthesis • Red Giants • Large stars that have exhausted hydrogen fuel in their cores and go on to ‘burn’ (i.e., fuse) He, C, O, etc. • Creation of elements up through Fe • Extra neutrons can be captured to produce heavier elements • Supernovae • Once core is converted to iron, large stars collapse and then explode • Enormous numbers of neutrons produced are captured to produce heavy elements

  24. Forming Other Elements As stars collapse, a shock wave forms and blasts out through the star, releasing enormous amounts of energy in a few seconds. All the outer layers of the star become superheated plasmas, with temperatures high enough to fuse iron and heavier elements, like gold and uranium. These bright outer layers are ejected by the star (which we call a supernova). While scientists still don’t completely understand the process, the collision of neutron stars and supernova explosions appear to be the “creators” of the heavier elements. Remnant of supernova E-0102-72.

  25. Formation of Heavy Elements • Most of the atoms in universe(hydrogen) formed very short time period after the Big Bang,the others(carbon,oxygen and iron)formed in stars. • Formation of elements heavier than iron(iodine,molybdenium,etc)needs more energetic conditions than in stars. • These more energetic conditions formed when giant stars exploded (supernovae explosions). • In supernovae explosions nucleides are bombarded with neutrons so capture neutrons to form to form a heavier isotope.Then emits beta particle to form a new element:

  26. Abundances of the chemical elements in the Solar system. Hydrogen and helium are most common, from the Big Bang. The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers, and (2) a general decrease in abundance, as elements become heavier. Within this trend, a slight preponderance of iron and nickel is seen, in keeping with these elements' high nuclear stability. Abundances of the chemical elements in the Solar system • Hydrogen and helium are most common, from the Big Bang. • The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. • The two general trends in the remaining stellar-produced elements are: • an alternation of abundance in elements as they have even or odd atomic numbers, and • a general decrease in abundance, as elements become heavier. Within this trend, a slight preponderance of iron and nickel is seen, in keeping with these elements' high nuclear stability.

  27. Relative abundance of elements in the world

  28. Composition of the Crust

  29. Percent Abundance of Elements(comparison)

  30. Yerkabuğundaki Elementlerin Yüzde Bollukları Tablodan da anlaşıldığı gibi, yerkabuğunun ağırlıkça % 99'unu 7-8 element oluşturur. Bu temel 7-8 element, çeşitli kombinasyonlar halinde bir araya gelerek mineralleri, mineraller de kayalarıoluşturmaktadır. Dolayısıyla, kaya ve mineralleri tanıyıp anlayabilmek için daha fazla elementi tanıma zorunluluğu yoktur. Kayaların hacimce % 90'nını oksijen oluşturur. Tabloda bazı elemenler genellikle mineralleri halinde bulunduğu görülmektedir.

  31. References • http://www.ehow.com/info_8527601_stages-big-bang-theory.html • http://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis • http://en.wikipedia.org/wiki/Nucleosynthesis • http://hyperphysics.phy-astr.gsu.edu/hbase/nucene/nucbin.html • http://gcserevision101.wordpress.com/physics-p3/ • http://www.thekeyboard.org.uk/The%20Big%20Bang%20Theory.htm • http://www.meta-synthesis.com/webbook/32_n-synth/nucleosynthesis.html • http://library.thinkquest.org/17940/texts/nucleosynthesis/nucleosynthesis.html • http://aether.lbl.gov/www/tour/elements/early/early_a.html

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