Wednesday, January 12, 2011
Филипенко Г.Г.
К вопросу о металлической связи в плотнейших упаковках химических элементов
Оригинал: http://lib.izdatelstwo.com/Papers/1.174.pdf
in Russian please see at:
What really is in your fish tank? - "Fishy" Ionic Compounds
Thursday, December 16, 2010
What spot in your house has more chemicals in one place than any other spot? Possibly the laundry room or cabinets under your sinks where you keep cleaning supplies. But if you have a fish tank, it might even be the place where you keep your aquarium supplies!!! Between pH balancers, mineral supplements, and chemically processed fish foods, there are bound to be many ionic compounds throughout.
So let's try to identify and name a few that I have found:
(This is a Prezi that names 20 ionic compounds that I identified on various aquarium related products.)
Entire Honors Chemistry Midterm Exam Review
Sunday, November 28, 2010
For anyone who would like a nice review and description of many basic topics of chemistry that I covered the first trimester, just click on the link below to download a PDF with these many topics. It is our Midterm Exam Review that we completed before taking our test. Thanks!!!
Honors Chemistry 2010 Midterm Exam Review
Midterm Review Question #24 - Electron Affinities
Oh, exam week!!! The wonderful weeks in each year were you review what you have learned (and possibly relearn a few things as well)!!! Well, at least our teachers diligently create thorough reviews to make the study process easier.
Here is the answer and explanation of question number 24 of our midterm review:
24) Which element on the periodic table should have the most favorable electron affinity? Which element would have the most negative electron affinity value? Explain your choices.
Essentially, these two questions are asking the same thing. The element that has the most favorable electron affinity is actually the element that has the most negative electron affinity value. The electron affinity value measures how much energy is released when an atom gains an electron or the amount of energy required for an atom to gain an electron. The more negative the electron affinity value of the element is (the more favorable electron affinity), the greater the amount of energy an atom releases when it gains an electron. Positive electron affinity values signify that for the atom to gain an electron, energy must be added to the atom (this arrangement is very unstable and when the application of energy is ceased, the atom will expel the electron and return to a lower energy level).
The image above is a 3D graph of the electron affinity values of the various elements of the periodic table. As can be seen, chlorine has the most favorable electron affinity, just a bit more favorable than fluorine, the electronegative element.
The reason that chlorine (Cl) is the element with the highest electron affinity (the most negative value) is very similar to the reason that fluorine is the most electronegative element. As it is in Group 17, chlorine is longing to obtain the electron configuration of the noble gas argon by gaining one electron and becoming a 1+ cation. It has a strong attraction to electrons due to its strong positive charge in its nucleus (compared to the other elements in its period). Furthermore, as chlorine is relatively high in the periodic table (it is in one of the lesser periods), there are fewer orbital “shells” shielding free electrons from the positive attraction of the nucleus. Thus, a large amount of energy is released when chlorine gains an electron.
Interestingly, the reason that chlorine has a larger electron affinity than fluorine, even though fluorine is the most electronegative, is due to the fact that fluorine is a smaller atom than chlorine. When an electron is added to fluorine, there is a greater repulsion between the electrons in the orbitals than there is with chlorine. Thus, even though fluorine might be more electronegative than chlorine, chlorine has a more favorable electron affinity.
Attributions:
Electron Affinity 3D Graph: http://www.webelements.com/periodicity/electron_affinity/cityscape_chart.html
Chadwick and the Neutron: A "Brainblast" into the Future of the Atom
Wednesday, October 6, 2010
[13]
Hi, my name is Jimmy Neutron. What comes to mind when you hear the word “Neutron”? If you have ever had young children, you may think that this term refers to a member of my family, or maybe me, the animated “Boy Genius” introduced to viewers on Nickelodeon in 2002. Besides thinking of me, most scientists would tell you that a “neutron,” similar to its well known brother the “proton,” is a subatomic particle found in the nucleus of all atoms and isotopes beyond protium, the isotope of hydrogen with no neutrons whatsoever. Unlike the proton, however, a neutron carries no ‘net’ electric charge and has a mass slightly larger than that of a proton. According to WolframAlpha, the mass of a neutron ≈ 1.001378 proton masses [12]. Speculated as to its possible existence as early as 1920 by Ernest Rutherford, its discovery in 1932 by English physicist, James Chadwick, signaled the beginning of the era of the common model for atomic structure and the basis of the picture of particle physics that remains valid today.
I don't know if you knew this, but my name full name, James Isaac Neutron, is actually a combination of Sir Isaac Newton, the father of classical physics, and physicist Sir James Chadwick, who was nicknamed "Jimmy Neutron" after his discovery of the neutron in 1932.
So why do these neutrons matter anyways? For if Chadwick had never discovered the neutron, we would not have stunning pictures like this: two neutron stars colliding and giving off gamma-ray bursts.
Before we delve into the world of the wonderful neutron, let us first review some basic information about the atom:
The smallest particle from which matter is created was named “atom,” meaning that which cannot be divided, by the Greek philosopher Democritus about 2500 years ago [3]. Thus, while we all now know that matter can be further subdivided, the atom remains the smallest structure that an element or material can be divided without changing its characteristics. It is composed of a dense, central nucleus surrounded by shells of negatively charged electrons bound to the nucleus by an electromagnetic force. The atomic nuclei of all elements and isotopes after protium contain a mix of positively charged protons and electrically neutral neutrons. Atoms are classified according to the number of protons and neutrons in its nucleus: the number of protons specifies the chemical element, and the number of neutrons specifies the isotope of the element.
In order to describe to you the process by which Rutherford and Chadwick came across the neutron, I have created three glogsters and a prezi to help explain some general areas regarding their work and, hopefully, give you a greater understanding of the role and discovery of the wonderful neutron!!! To view the Glogs and the prezi simply click on the four links below:
Glog on Biographical Information of James Chadwick
Glog on the Predecessors of the Discovery of the Neutron
Prezi on Chadwick's Main Experiment
Glog on the Significant Effects of the Discovery of the Neutron
For those history lovers out there, here is a primary source for your enjoyment. It is the letter that Chadwick wrote to Nature about his discovery of the neutron: Chadwick's Letter to Nature
And just for fun, here is a picture of James Chadwick created with words used throughout my description of the discovery of the neutron. (This image was created with the web tool "tagxedo" at www.tagxedo.com.)
Works Cited File