Volume 1
Issue 5
November, 2013
Discovery of the nucleus
Earnest Rutherford the discoverer of the nucleus. He discovered the nucleus in 1897. The experiment he used was s particle beam shooting particles at gold foil. The particles positively charged bounced of the nucleus which has a positive center. His work won him the Nobel
Peace prize by showing that There is a smaller part to the Atom.
His
work
benefits
us
today cause we understand the smaller parts of an atom. His experiment helps us see how the Nucleus is positive and is surrounded by negative charges. A few things about the experiment that we didn’t like are how he found the nucleus but he really didn’t understand it. But overall since he won the Nobel peace prize his discover had to pretty amazing for his time.
By: Ben Hale, Ali Muhammad
By Edgar Sanchez, and Sean Good November, 2013
James Chadwick discovered the neutron in the nucleus of an atom in 1932. He was born October 20th, 1891 in Cheshire, England, and died on July 24th, 1974. He’s the son of John Joseph, and Anne Mary. He went to Manchester High School, and then went to Manchester University in 1908. He graduated from the Honors School of Physics in 1911 and spent the next two years Professor Rutherford in the Physics Laboratory in Manchester, where he worked on various radioactivity problems, gaining his M.Sc. degree in 1913.
James bombarded boron with alpha particles witch emitted neutral rays and placed a hydrogen target in the path of the rays. When the rays hit the hydrogen target, protons the Laws flew out. He measured the velocity of the protons. Using the Laws of conservation of momentum he was able to calculate the mass of the neutral particle. From the velocity of the protons flying out, he can calculate the mass of the projectile, in this case the mass of the neutrons. The mass of the neutral particle is 1.0067.
James found out what caused the mass of the atom, and his model was accurate. He was the last scientist to be correct about what the atom had in it so there weren’t any holes in his logic. H.J. Tayler who took his studies to find solutions for cancer cures. The neutron is the main mass of the nucleus, and his model proved it.
JACOB HOLLISTER B.3 gold Nov. 2013
Ernest Rutherford is one of the many scientists to work with the atom. He is also one of the ones that made a big break through with the atom. Rutherford found space and the nucleus in the atom due to extensive research. Instead of the plum putting model where it is just on ball with electron “balls” in closed by a positive cover, Rutherford found the nucleus and space between the electrons of an atom (element). The atom was changed yet again in time. Rutherford was born in 1887 and started work right away going to college and worked under J.J Thompson helping him in his findings. In the 1900’s he did extensive work with radiation and alpha and Bata rays. He found radon a very radioactive gas and discovered that heavy atoms decay faster and give of radiation and light atoms decay slower. In 1904 he published his first book called Radioactivit. In 1908 he was given the Nobel Prize in chemistry. After the prize he started his real work in 1909 with the atom. Rutherford’s main experiment that helped him find the nucleus was the gold foil experiment. He had a microscopic thin gold foil sheet (seen in the picture below) and shot alpha particles (helium atoms striped of their electrons) at the gold sheet. Some of the particles bounced of to the side some went straight through the sheet. Rutherford studied and studied this and finally wrote a paper on it saying that an atom is the densest and holds the most mass in the middle called the nucleus (one billionth the total size of the atom) and has space around the nucleus where the electrons are. He shot the particles at the foil and if they bounced off the sheet it hit the atom or got close, when it went thru the sheet it went passed between the gold nuclei (seen in the figure below). So he found the nuclease and space between it and the electrons. The impact on people is big the atom is totally remade. Rutherford is the only man to get the Nobel Prize be for his best work was done. His work would have taken a long time and kind of boring. His work showed that there is a vast realm of emptiness between the nucleus and electrons and other nuclei, shows that all the mass is in the nucleus (due to neutrons, they are not found tell 1932) and proved that all the atoms particles were not all mashed up together. Additionally the nucleus is a positively charged practical and the electron is negatively charged. This model of the atom was widely accepted and helped form quantum mechanics.
Discovery of the Neutron
By-jeanna Roark and May Joy
November, 2013 In 1919 Ernest Rutherford discovered the proton. He and fellow scientists including James Chadwick noted that it seemed like there was more than just a proton in the atom. Overseeing James Chadwick’s work Chadwick discovered the neutron. While experimenting James Chadwick noticed that in an element of the periodic table the atomic mass was more than the atomic number. He figured that there must be something else in the atom that was adding to the atomic mass. Experiments in Europe caught his eye and he repeated them with the hopes that he would find that there was a particle with the same mass as a proton but with zero charge, and there was. He called it the neutron. In his experiment he smashed alpha particles into beryllium, a rare metallic element, and allowed the radiation that was released to hit another target: paraffin wax. When the beryllium radiation hit hydrogen atoms in the wax, the atoms were sent into a detecting chamber. This experiment showed that the collision would result in a release of neutral particles.
THERE IS A NEUTRON!!!!
Discovery of the Nucleus Kenzie Hawxby and Ellyn Sullivan Published November 2013
English physicist, Ernest Rutherford, is given credit for discovering the nucleus in 1911. Rutherford had a successful career in atomic physics. Throughout his career, he taught and led many other famous physicists. Through experiments with other scientists such as Marie and Pierre Curie and Henri Becquerel, they learned most of what we know today about the atom, including the discovery of the nucleus.
While Rutherford was a professor at the University of Manchester, he worked with Hans Geiger in one of their most well-known experiments. The two men beamed alpha particles at a thin sheet of gold foil. While conducting the experiment, the physicists noticed that most of the particles passed through the gold foil onto the screen behind it, but some were deflected. Rutherford came to the conclusion that the particles that made up the gold foil must consist mostly of empty space since most of the alpha particles passed through. Rutherford speculates that some parts of the gold must have been too dense to let the alpha particles through and this heavy part of the atom was what Rutherford called the nucleus. He decided that the nucleus is what held most of the atoms mass. Rutherford’s work led to the splitting of the atom, which led to the discovery of the proton, proving great significance in the physicists work. Deflected: the action or process of deflecting or being deflected
By Lukas Powley November, 2013 The discovery of nucleus was made by Ernest Rutherford. This amazing scientific event happened in the 1890’s. This changed all scientists’ opinions on the atom from that point on. Since Rutherford was the first to discover the nucleus, he had the first opinion on what it looked like and what was in it. Rutherford thought that the nucleus had a positive charge with negative subatomic particles. To conduct the theory of the nucleus, Rutherford did an experiment which included particles traveling through a thin piece of gold foil with a positive charge. Now to know that they had a positive charge, Rutherford shot particles into the gold foil and waited for them to reflect off. Since the gold foil was positive, we know the particles that are bouncing off also have a positive charge because positive reflects positive. Overall this was just the beginning. Scientists’ like Bohr, Chadwick, Hensen and many more all had different ideas on the atom after the discovery of the nucleus.
THE DISCOVERY OF THE ELECTRON
Martine Graves Mahlik Canada Nov. 2013
In 1897 a British physicist discovered the election. His name was Joseph John Thomson; He discovered the electron by going through a series of experiments intended to study the nature of electric discharge. This was an area being investigated by numerous scientists at the time so the discovery was very important because it opened the door to new ideas.
THOMSONS EXPERIMENT J.J. Thomson studied the electrical discharge in a high-vacuum cathode-ray-tube; he interpreted the deflection of the rays by electrically charged plants and magnets. In 1904, Thomson assumed a model of the atom as a sphere of the positive matter in which electrons as positioned by electrostatic forces. Just like how you can’t combine a positive magnet with another positive magnet. However his conclusion was the electron, but found an unknown sub particle later discovered by Rutherford. He died in 1904. Not only did his discovery play a big role in the future discoveries of the atom but it was also the reason for more experiments on electrons. He was a teacher and won a Nobel Peace Prize for his discoveries.
By: Mai Dang November, 2013 What is a neutron to begin with? Are we talking about neutron stars or Jimmy Neutron? No, we're actually talking about neutron particles in atoms! First of all, who discovered the neutron? It was James Chadwick who was the one to name and discover the neutron in 1932 because of his experiment. His research was mathematical and was laid out from data.
He began his experiment by choosing an element from the periodic table. In the diagram for example, he chose Beryllium. Using kinematics and data, he was able to figure out and determine the velocity of the protons. Then through conservation of momentum techniques, he was able to determined, that the mass of the neutral radiation was almost exactly the same as that of a proton. This was Chadwick's equation:
The diagram on the left is the overall atom conclusion/model of his research. In his actually experiment he was able to determine the mass which lead him to conclude the following. We now know that electrons were located outside the nucleus and contain no mass from Bohr. If you check the atomic mass of the atom (that Chadwick created with his equation); you see that the mass is greater than the number of protons, so where these extra mass did came from if mass can't be added on or taken off. It can only mean that there is some other particle in the atom. If there is another particle it needed to be located in the nucleus because that's where mass comes from. Chadwick realized this, and concluded the new particle had to be neutral (because it was in the nucleus so it wasn’t negative, and the number of protons of an element can’t change). Thus, he named this neutral particle the neutron. The discovery of neutrons!
Plum Pudding Model By Osman Bajric & Allan Breskic Definition of Cathode ray: A radiation that originates from the cathode and travels to the anode of a cathode ray tube.
11/5/13 Gold 4 Chemistry Eric Hall
Do you know who discovered the electron? Well we do, it was discovered by J.J Thomson in 1897. In Thomson’s discovery he founded the electron by his Plum Pudding Model he created. In Thomson’s Plum Pudding Model the plums where the negatively charged particles (electron) and the plums were surrounded by positively charged pudding. Before Thomson made his Plum Pudding model he did a series of cathode ray tube experiments. Sir William Crookes laid down the ground work on the cathode ray by discovering it on accident. The cathode ray had negatively charged particles in it that were found in all kinds of matter, they are now called “electrons”. No one was able to measure the mass of these particles in the cathode ray, that’s when J.J Thomson comes in to determine the ratio of its charge to its mass. Thomson measured the effect of the magnetic and electric fields in the cathode ray. Thomson was able to find the charge-to-mass ratio of the particle. Thomson compared the mass of this negatively charged particle to other particles. Thomson concluded that that the mass of the negatively charged particle had a lower mass than a hydrogen atom which was the lightest atom. By this evidence Dalton’s theory was wrong that atoms were divisible into smaller subatomic particles. Thomson discovered the first subatomic particle, the electron. Thomson then proposed the Plum Pudding Model to answer the question of “If all electrons are in matter and they hold a negative charge, then how is it that all matter is neutral”. Thomson’s Plum Pudding Model was a spherically shaped atom made up of a uniformly distributed positive charge with which each negatively charged electron. In 1911, Ernest Rutherford did a experiment to test the plum pudding model. He fired energetic A [He2+] particles at the foil. Then he measured the deflection of the particles as they came out. Rutherford expected that the particles to be deflected just a little bit as they passed through the plum pudding. He found that most A’s that were shot at the foil did not deflect off the foil. The passed through the foil and emerged undisturbed. Rutherford’s results lead him to believe that most of the foil was made of empty space, but of extremely small, dense lumps of matter inside. With this experiment he discovered the nucleus. This experiment made Thomson’s Plum Pudding Model wrong, but we have to give Thomson credit because he founded the electron and also saying that there positive and negative charge was balanced out, which it was balanced but Thomson could not exactly find the right place where that positive charge was. That is what Rutherford did, he found that the balance was in the nucleus.
Olivia Evans Plum Pudding Model November 2013 J.J. Thomson theorized that the atom had negative particles throughout the atom which is positive itself. This is also referred to as the “plum pudding” model. Thomson discovered this model around 1897, which was when the Klondike Gold Rush was happening. In order to discover this model of the atom, he conducted and experiment known as the Cathode Ray Experiment. Thomson observed the deflection of cathode rays by an electric field. Thomson used a Cathode Ray in which the two electrodes are separated by a vacuum. When a voltage is applied across the electrodes, it creates a glowing patch where they hit the glass at the opposite end of the tube. Thomson’s theory of the atom was incorrect. Ernest Rutherford performed an experiment where he fired protons at a sheet of gold foil. According to Thomson’s model, all of these protons should have gone right through the foil. However, it was found that some of the protons were deflected back towards the proton source. Rutherford concluded that an atom was comprised of electrons orbiting a small, massive, positively charged nucleus.
Thomson’s theory impacted our world today in a massive way. He changed how every scientist thought about atoms. He proved the existence of electrons by conducting the Cathode Ray experiment.
Samuel Buckton Chemistry Gold 4
Background Knowledge
There are numerous theories about what the atom is composed of, some which are more recent and accurate than others. The first most significant atom model was discovered by J.J. Thomson. Thomson’s model is very simple, consisting of negatively charged particles in a positively charged atom. This concept’s is more commonly known as the plum pudding model, due to the resemblance of plum pudding. Thomson conceived his experiment in the late 1800’s, around the same time as the Spanish-American War.
The Experiment Although the plum pudding model is not the most accurate demonstration of the atom, Thomson didn’t just pull the concept out of thin air. He conducted many experiments using a tool known as the cathode ray tube. A cathode ray tube is a hollow tube of glass that doesn’t contain air. Additionally, the tube has an electrical filament on one side to allow electrical current to pass through, and a fluorescent screen on the other. By passing an electrical current throughout the cathode ray tube, he was able to observe the deflection of cathode rays on the fluorescent screen and because of this, Thomson was able to discover the electron. This was a massive breakthrough in the knowledge of atoms at the time.
Is It Accurate? Thomson’s model displays simple information of an atom, but not enough to understand the full picture. The model displays electrons correctly, but is missing the nucleus, which is a key component of the atom. Also, the displacement of the electrons is incorrect, due to the fact that they orbit the nucleus, while Thomson’s model didn’t even contain the nucleus. Furthermore, his model doesn’t show the neutrons or the protons. To summarize it, Thomson had some components of his model correct, but didn’t have enough to make his model accurate.
How Is It Important? In many cases, it may seem as though Thomson’s model is not significant. His model is incorrect in some ways, yes, but this was the first model of an atom. This model helped create a basic understanding of the atom to help further experiment to understand the atom on a more advanced level. Additionally, the atom is the basic unit of all living things, meaning understanding the atom can lead to numerous discoveries.
Electron Cloud Model By. Tirfiya Musa In 1913 Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr’s theory could explain why atoms emitted light in fixed wavelengths. The word electrons are associated with electrons. It proposed a possible way electrons move around the nucleus. The significance of this discovery is that it introduced the idea of quantized energy levels. It laid the foundation for further understanding of electrons. The shortcoming of this theory is that It can only be applied to single electron atoms (hydrogen) or ions. It also fails to explain why some spectrum lines are brighter than others. This theory violates Eisenberg uncertainty principal by assigning a fixed position and momentum to the electron simultaneously.
,
Erwin Schrödinger was born on August 12, 1887 and die on January 4 1961. He was an Austrian physicist who won a Noble prize in 1933 for the discovered of Quantum Mechanics equation, the way of calculating wave’s movement, or behavior. He used this equation to prove his electrons movement, another discovered he is famous for. Schrödinger was inspired by Albert Einstein work. Most of his experiments are not lab work experiments, but basic mathematics. In 1926, Schrödinger propose his discovered that Bohr was missing some information according to what he claimed electron do in the Planetary Model. Bohr said that, electrons go orbit around the Nucleus, the center of an atom that contains its mass that was discovered by Rutherford by his Gold Foil experiment in the same way that the planets orbit around the sun. To prove his claim, Schrödinger created his Electron Cloud model. The electron cloud model described the levers of energy in which the electrons travel from one energy level, or ring to the next energy level.
Bohr
Schrödinger
To further enhance his model, Schrödinger proved that not just do electrons works as a waves, but you can predict where they will be located next. The probability of finding an electron in a dense area around the nucleus is greatest then less dense area. So, that being said there are area where the electrons are most likely to be found. One thing both Bohr and Schrödinger agreed on is that, the electrons do move around the nucleus, but not in the way Bohr thought movements was. Also, that the electrons have energy levels, as Bohr claimed.
This is some of Schrödinger equation he used, with the help of Heisenberg Uncertainty Principle, which state that it is impossible to find both the position and momentum of an electron at the same time to prove what was missing in Bohr’s work.
By Isaac Moore
November, 2013
Who is the man behind this discovery? The man who created the planetary model was Ernest Rutherford, a New Zealand physicist and chemist who became known as the father of nuclear physics. In 1911, although he could not prove that it was positive or negative, he theorized that atoms have their charge concentrated in a very small nucleus, and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment. He is widely credited with first "splitting the atom" in 1917 in a nuclear reaction between nitrogen and alpha particles, in which he also discovered and named the proton.
The reasoning behind the gold foil Back in 1911, no one knew exactly what the atom really looked like. All they had was the plum pudding model suggested by JJ Thompson. In this model the electrons and protons are uniformly mixed throughout the atom. Rutherford decided to test Thomson's hypothesis by devising his "gold foil" experiment. Rutherford reasoned that if Thomson's model was correct then the mass of the atom was spread out throughout the atom. Then, if he shot high velocity alpha particles at an atom then there would be very little to deflect the alpha particles. He decided to test this with a thin film of gold atoms. As expected, most alpha particles went right through the gold foil but to his amazement a few alpha particles were deflected almost directly backwards.
The birth of the planetary model These deflections were not consistent with Thomson's model. Rutherford was forced to discard the Plum Pudding model and reasoned that the only way the alpha particles could be deflected backwards was if most of the mass in an atom was concentrated in a nucleus. He thus developed the planetary model of the atom which put all the protons in the nucleus and the electrons orbited around the nucleus like planets around the sun. This model was very important discovery. This model was used as the base for all modern element models today. Without this discovery, we might think the atom still looks like plum pudding.
Supacheep Veerapaiboon November 2013
In 1919, Ernest Rutherford discover a proton, a positive charges, locate in the nucleus
of an atom. But because the study shows that the atomic number, number of protons, of an element was less than the atomic mass, some researchers think that protons are not the only particles in the nucleus.
In 1930 it was discovered that Beryllium can emitted a very energetic stream of radiation. These rays were not deflected upon passing through a magnetic field, neutral. Two years after, in 1932, James Chadwick proposed that this particle is neutron. Chadwick can determine the velocity of the protons by using kinematics and because of momentum techniques, he can find the mass of the neutral radiation was as same as the mass of proton.
James Chadwick The equation that James Chadwick use to prove about the existing of neutron.
Neutron is the significance of this discovery. We gain a lot of benefits by study about neutron such as we can applied a neutron radiation in medical profession. X-rays is an example of neutron radiation that use in medical profession.
James Chadwick was a English physicist that discovered the neutron. He found that there was something in the nucleus that was giving an element mass besides the proton. He did some experiments that was searching for a neutral particle. Scientists thought that the nucleus was made up of protons and electrons, but since electrons have no mass, there had to be another particle making us the atomic mass of an element.
Chadwick blasted particles into different elements like Boron and Beryllium. They hit specific targets that transferred atoms to a neutron chamber. Beryllium gave off radiation that hit the targets and released neutral particles. He called them neutrons. Chadwick's experiment was mathematically correct. There were no problems in his experiment because he successfully found the missing particle in the nucleus that gave an element its mass.The model of the atom that we know today was completed by Chadwick and his discovery of the neutron.
Chadwick's discovery allowed scientists to make nuclear weapons. It's important to our society because countries with nuclear power has been a conflict in the world. Chadwick even helped with the making of the atomic bomb, which back then if you had it, you were indestructible.
November 2013 By Jordan Christensen
The atom is not only an important thing to have knowledge of, but it’s part of everyone’s life, literally! Atoms make up everything single thing in this world, but it took a very long time for scientist to figure out what we know of today as the model of the atom. The model of the atom went through many phases and many discoveries were made over time to find today’s current model but I believe the most important discovery was the discovery of the Nucleus. In 1911 a scientist by the name of Ernest Rutherford discovered that an atom has a nucleus. This crucial discovery was made by a tedious experiment involving an alpha ray gun, a sheet of gold foil, and walls set up around the experiment. The sheet of gold foil was set up so that the alpha ray gun would shoot through the foil and hit part of the wall. Deflections of the rays were counted by scientist sitting outside of the wall and watching for dots. For the most part the rays went right through the gold foil, but some were deflected slightly, and some were even deflected straight back at the gun. Taking into account that some were deflected shows that there was another aspect of the atom which Rutherford concluded to be a positive nucleus. The problem with this experiment was how tedious the process was. Counting the dots was done in a dark room, the scientists would count for 10 minutes, then leave the room for about 2 hours so their eyes could adjust back to the light, and then go back in for ten minutes. Not only was this tedious but it wasn’t necessarily accurate, having computers/technology counts deflections would have been much better for data than having scientists try to count every deflection. The discovery of the nucleus impacted the current representations of the periodic table and elements, but was pre- isotope, ion, atomic number, electron configuration, and electromagnetic spectrum, but I believe Rutherford conducted the best experiment he could have in that age in history and deeply contributed to the current model of the atom. After all, who knows, without Rutherford’s experiment and conclusion, even today we may not have had a knowledge of the nucleus.
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