Chemistry
This article is an introductory discussion of the Science of Chemistry with a video. The page also includes a copy of the periodic table.
Showing posts with label atoms. Show all posts
Showing posts with label atoms. Show all posts
Thursday, November 10, 2011
Wednesday, October 26, 2011
An Introduction to the Science of Chemistry
Chemistry: The field of science that is the study of the interactions of atoms to form molecules and their properties.
The beginnings of Chemistry go back to before known civilization with fire and metal work. According to the book of Genesis in the Bible metal work goes back to Tubal-cain who lived before the Flood. Modern Chemistry grew out of Alchemy and its search to turn metals like lead into gold and the so called elixir of life. Chemistry got much from Alchemy particularly its affinity research and experimentation. Once Chemistry broke from Alchemy it lead to an explosion of knowledge about the nature and structure of matter.
The Periodic Table is a list of the chemical elements organized by recurring properties. The information about each element included varies but often includes element’s name, atomic number, symbol, and atomic weight. It is a vary use full took in Chemistry and one the most recognizable things associated with Chemistry.
Chemical reactions are the process by which atoms come together or are rearranged to form new molecules. There are two main types of chemical reactions. Endothermic reactions which use heat energy in forming new molecules and exothermic reactions which release heat energy in forming new molecules. Exothermic reactions are some times explosive which is a common danger in Chemistry.
There are two main fields of chemistry. Organic chemistry which is chemistry based on the element Carbon and may or may not involve life and inorganic chemistry which is chemistry not based on the element Carbon.
In conclusion chemistry is a major field of science and it is the most experiment based field of science. Chemistry embodies the ideal of science stated in the scientific method more than any other field of science.
The beginnings of Chemistry go back to before known civilization with fire and metal work. According to the book of Genesis in the Bible metal work goes back to Tubal-cain who lived before the Flood. Modern Chemistry grew out of Alchemy and its search to turn metals like lead into gold and the so called elixir of life. Chemistry got much from Alchemy particularly its affinity research and experimentation. Once Chemistry broke from Alchemy it lead to an explosion of knowledge about the nature and structure of matter.
Chemistry begins with individual atoms of different elements such as hydrogen, carbon and oxygen. Atoms come together to form molecules such as water which is made of one oxygen atom getting together with two hydrogen atoms, methane which is made of one carbon atom getting together with four hydrogen atoms and carbon dioxide which is made of two oxygen atoms getting together with one carbon atom. These are all different substances with different properties.
The Periodic Table is a list of the chemical elements organized by recurring properties. The information about each element included varies but often includes element’s name, atomic number, symbol, and atomic weight. It is a vary use full took in Chemistry and one the most recognizable things associated with Chemistry.
Chemical reactions are the process by which atoms come together or are rearranged to form new molecules. There are two main types of chemical reactions. Endothermic reactions which use heat energy in forming new molecules and exothermic reactions which release heat energy in forming new molecules. Exothermic reactions are some times explosive which is a common danger in Chemistry.
There are two main fields of chemistry. Organic chemistry which is chemistry based on the element Carbon and may or may not involve life and inorganic chemistry which is chemistry not based on the element Carbon.
In conclusion chemistry is a major field of science and it is the most experiment based field of science. Chemistry embodies the ideal of science stated in the scientific method more than any other field of science.
Monday, October 17, 2011
The Quantization of Quantum Mechanics
Quantization: The situation where physical quantities like position, energy and momentum can have only certain discrete values.
While a particle’s position, energy and momentum in free empty space are continuous, if the particle is bound to an area of space can only have certain discrete values. The energy contained in a given frequency of electromagnetic waves is quantized in that it always has the same value at the same frequency. The electromagnetic energy is found in discrete packet called photons.
The quantization of the energy od an electron within an atom explains much of their behavior such as why atoms emit only discrete frequencies of light. An electron that is in a low orbit of an atom can absorb a photon causing the electron to jump to a higher orbit. The electron then emits a photon jumping back to the lower orbit.
The quantization of space-time us based on several natural units proposed by Max Planck that are based on five universal physical constants: Gravitational constant, Reduced Planck constant, Speed of light in a vacuum, Coulomb constant, and Boltzmann's constant
While most of them have no physical significance two of them Planck Length and Planck Time are the smallest possible measurements of space-time according our current understanding of the laws of Physics because of the uncertainty principle when a plied to these scales. This suggests that time and space themselves are Quantized.
Planck Length = 1.616 252 × 10−35 m
Planck Length is the smallest measurement of length that has any meaning with in the laws of physics as we understand them today.
Planck Time = 5.391 24 × 10−44 s
Planck Time is the amount of time it takes a photon to cross a Planck Length. It is the smallest measurement of time that has any meaning with in the laws of physics as we understand them today.
Quantization requires physical quantities like position, energy and momentum to have discrete values explaing much of what goes on in side atom and based on our current understanding of the laws of physics it suggest that time and space are quantized.
Monday, October 10, 2011
Atoms, Their Every Thing
Atom: The basic unit of matter that consists of a dense, central positively charged nucleus surrounded by a cloud of negatively charged electrons.
This problem led to modeling the atom as a solar system called the planetary model with electrons orbiting the nucleus like planets around a star. The problem with the planetary model is that electrons are charged particles and an accelerating charge emits light loosing energy and this would cause the electron to spiral into the nucleus.
Broglie had shown earlier that particles have wave like propertied. Bohr then used this by showed that these waves could be bent into orbits like those expected for an electron with the result that electrons can only occupy those orbits with exactly a whole number of wavelengths. In these orbits the waves are add together with constructive interference. If an orbit has a fractional number of wavelengths the wave would destructively interfere and not persist so an electron can not occupy such an obit. The result is that that electrons jump from orbit to orbit emitting photons when going to a lower orbit and absorbing photons are when going to a higher orbit. It turns out that transitions between the possible electron orbits, matches the spectral lines that are actually observed in hydrogen. This was a major step in development quantum Mechanics.
Studying elements other hydrogen included the effects of multiple electrons resulted in the electron orbital five of which are shown above. They are places in an atom where electrons can actually be found. The shapes of these orbitals were originally found mathematically and they have long been viewed as purely mathematical abstractions that were never expected to be seen. Physics students have long been told this however field-emission electron microscopy has changed this.
The Rutherford Gold Foil Experiment was suggested by Ernest Rutherford and conducted in 1911 by Hans Geiger and Ernest Marsden. It Involved shooting alpha particles (He nuclei) at a gold foil to observe how they are scattered by the gold on a screen. It probed the structure of the Atom.
If it were a solid mass few if any alpha particles would get through. If negative electron were embedded in a thin positive mass all of the alpha particles would get through. However most of the alpha particles get through with some being scattered by the small positive nucleus.
Rutherford Conclusion was that the atom is mostly empty space with a small positive nucleus surrounded by electrons scattered through out the surrounding space. In such a model the electron can not stand still since if they did they fall into the nucleus
This problem led to modeling the atom as a solar system called the planetary model with electrons orbiting the nucleus like planets around a star. The problem with the planetary model is that electrons are charged particles and an accelerating charge emits light loosing energy and this would cause the electron to spiral into the nucleus.
The Bohr Atomic Model
Broglie had shown earlier that particles have wave like propertied. Bohr then used this by showed that these waves could be bent into orbits like those expected for an electron with the result that electrons can only occupy those orbits with exactly a whole number of wavelengths. In these orbits the waves are add together with constructive interference. If an orbit has a fractional number of wavelengths the wave would destructively interfere and not persist so an electron can not occupy such an obit. The result is that that electrons jump from orbit to orbit emitting photons when going to a lower orbit and absorbing photons are when going to a higher orbit. It turns out that transitions between the possible electron orbits, matches the spectral lines that are actually observed in hydrogen. This was a major step in development quantum Mechanics.
Further Development
Studying elements other hydrogen included the effects of multiple electrons resulted in the electron orbital five of which are shown above. They are places in an atom where electrons can actually be found. The shapes of these orbitals were originally found mathematically and they have long been viewed as purely mathematical abstractions that were never expected to be seen. Physics students have long been told this however field-emission electron microscopy has changed this.
In conclusion the imaging of actual electron orbitals was a surprise but it vividly shows the accuracy of Quantum Mechanics.
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