Volume 1
Issue 2
November, 2013
Dat Tran & Hiep Nguyen November 2013 It is remarkable that the neutron was not discovered until 1932 when James Chadwick used scattering data to calculate the mass of this neutral particle. Since the time of Rutherford it had been known that the atomic mass number A of nuclei is a bit more than twice the atomic number Z for most atoms and that essentially all the mass of the atom is concentrated in the relatively tiny nucleus. As of about 1930 it was presumed that the fundamental particles were protons and electrons, but that required that somehow a number of electrons were bound in the nucleus to partially cancel the charge of A protons.
At first James Chadwick had Alpha Particles which is 2 Neutrons and 2 Protons together. After he put the Alpha particles shoot through Paraffin Wax, he realized he lost half of the mass when he started experiment. He only found 2 Protons came out and really fast. Then he wonders where the other 2 went. He goes back check why did Protons came out really fast, then he realized that something has to be same size and same mass to shoot the protons to make it go fast. When the Alpha Particles shoot Beryllium out, it will has 2 Neutrons and the Neutrons shoot in Paraffin Wax that’s why the Protons came out fast. After the experiment, he discover Neutrons + Protons = Alpha Particles.
By Deiondre Greene November, 2013
Ernest Rutherford In August 30th 1871 a man named Ernest Rutherford was born. In 1909 is When he started to research on the atomic theory. In 1911 he made his Atomic model using a gold foil and alpha particles. In October 19th,1937 He passed away.
His Experimental Discoveries
Rutherford tested 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 rebounded almost directly backwards
By Hannah Gebert and Cassie Franklin November 4, 2013
Erwin Schrödinger took Bohr’s “Planetary” Model one step further to find out where the electron would be at any giving time in the motion of moving around the nucleus. As Schrodinger was doing this, he was using mathematical equations to find out where the electron would be, he took the equations Louis de Broglie used and added on to it to find out what he wanted to know about the location of the electron. As Schrödinger worked on his conclusion of the “The Quantum Mechanical Atomic Model” that described the electrons to be moving in waves around the nucleus of the element, he went on to explain that in the waves of electrons moving they were moving in a circular pattern. As Schrödinger was doing his experiment on finding the exact location of an electron in this cloud, his mathematical equation being used to find an electron at any giving point was too hard to understand, meaning Niles Bohr was the one to dumb down this and explain it better. Showing that the electron cloud was much simpler then it needs to be.
Ernest Rutherford, 1st Baron Rutherford of Nelson, OM FRS
was a New Zealand-born physicist and chemist who became known as the father of nuclear physics. He is considered the greatest experimentalist since Michael Faraday. Born: August 30, 1871, Brightwater, New Zealand. Died: October 19, 1937, Cambridge, United Kingdom. Awards: Nobel Prize in Chemistry, Copley Medal, Franklin Medal, Elliott Cresson Medal, Rumford Medal, Matteucci Medal, Faraday Medal More. Education: University of Cambridge. o Ernest Rutherford!
o Date: 1909.
In early work he discovered the concept of
radioactive
half-life,
proved
that
radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation. Ernest Rutherford publishes his atomic theory describing the atom as having
a
central
positive
nucleus
surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). The Rutherford model of the atom was simplified in a well known symbol showing electrons circling around the nucleus like planets orbiting the sun. This symbol became popular and has been used by various organizations around the world as a symbol for atoms and atomic energy in general.
In 1908, Rutherford was awarded the Nobel Prize in Chemistry
By: Hien Nguyen, November 2013
By: Tylen Chestnut and Jasmin Jabbar, Faith Gaye November 2013 How do you identify what something is and how it works? Scientist always discovers new things. With their discoveries we learn how things work and how it will benefit the rest of the world. One of the biggest scientific discoveries is the atom, which is found in different types of elements which are part of the periodic tale. A scientist named Joseph Thompson first discovered the idea of an atom and what it looks like. His work started in the late 1800’s. He had a general model of what the atom looked like. Thompson used more than one similar element also known as isotope. The atom was a large positively charged body containing electrons 1 surrounded by the positive charge. This was model was known as the Plum Pudding Model. He discovered what was in the atom by using the cathode ray 2 .The experiment was correct about atoms; they are primarily composed with space. But there were holes in this logic. If the electrons in an atom keep adding on to each element in turn there would never be a case where the mass of the electrons goes down. The mass always increases. This picture sums up Thompsons theory, the chocolate chips represents the negative electron; while the whole cookie represent a positive charged body.
Thompson’s Plum Pudding Model has been significant to our society by helping scientist create many more types of models that are based from his theory. Every field of science needs a template to base off of and improve work on Thompson created just that. Thompson plum pudding model was the first to discover what was inside of atoms. In the early 1900s Ernest Rutherford then later expanded off Thompson’s model as later scientist did.
By Alexis Larson & Mikayla Larson November, 2013
The Discovery of the
Neutron
Discover y
Who is Sir James Chadwick?
James Chadwick was born October 20 1891 and passed away July 24, 1974. He was an English Physicist that graduated from the University of Manchester where he studied under Ernest Rutherford. He was a citizen of the United Kingdom and is known for discovering the neutron.
The discovery of the Neutron‌ In 1932 Sir James Chadwick performed an experiment called the Compton Effect. This experiment performed by James Chadwick proved that there was such a thing as Neutron. The Compton Effect, in which photons impinging on a metal surface eject electrons. The trouble was that the electron was 1,836 times lighter than the proton and, therefore, recoiled much more easily than the heavier proton after a collision
with a gamma photon. We now know that gamma photons do not have enough energy to eject protons from paraffin. Now before believe him the experienced scientist repeatedly did the experiment. Only to find it works. This being very excited news James Chadwick shared it with his old advisor who thought it was an amazing accomplishment. This proving that there is a Neutron with the proton, photon, and a nucleus.
FUN FACT: The neutron carries no electric charge, allowing it to split the nucleus.
The conclusion After all the hard work and dedication James Chadwick received the Nobel Prize in 1935. Only 3 years after his discovery! His research was accurate and testable. This was only of the biggest step towards science history. Making it possible for our science minds to keep evolving.
WHO WAS J.J. THOMSON? Joseph John Thomson was born December 18, 1856 in Manchester, England. In 1870 he was admitted to Owens College at the age of 14. He moved to Trinity College in 1876. In 1880, he obtained his BA in mathematics, with 2nd Wrangler and 2nd Smith's Prize, and MA, with Adams Prize, in 1883. In 1884 he became Cavendish Professor of Physics. In 1914 he gave the Romanes Lecture on "The atomic theory". In 1918 he became Master of Trinity College. He died on 30 August 1940. WHAT DID HE DO? In 1897, he came up with the “plum pudding model”. The pudding was positively charged and the chunks of plums in it were the negatively charged electrons. The atomic nucleus had not been discovered yet, so the “plum pudding model” was put forward in 1904. In 1906, he won the Nobel Prize for his discovery of it. EVALUATION He did do a great job on helping understand an atom a little bit better and showing us how an atom stayed neutral. He also started the beginning of the atomic era of science and helped understand protons, neutrons and electrons. However, even with the Plum Pudding Model we still didn’t know how the electrons were arranged.
Maddie Neal November, 2013
Who is Ernest Rutherford? Ernest Rutherford was a chemist and physicist from Spring Grove, New Zealand. He attended Canterbury College where he received both a bachelors and a masters of Arts degree and a Bachelor of Science degree. While at college Rutherford was introduced to J.J. Thomson. This is how Rutherford got started with his research of the structure of an atom.
The Big Experiment! Rutherford was inspired by the work he observed J.J. Thomson doing but he thought there was something missing. Rutherford decided to do some experimenting of his own. Rutherford came up with an experiment using alpha
Figure 2
What Did Rutherford Discover? Rutherford saw that some of the positively charged alpha particles were being deflected back away from the piece of gold foil. (Figure 2) Rutherford came up with a theory to explain this. His theory was that there was a part of the gold atom that had a positive charge. From this he concluded that atoms contain a tiny, dense, positively charged center. This center is what is now known as the nucleus of an atom.
The Holes
Figure 1 particles. (Figure 1) He took alpha particles and shot them at a thin piece of gold foil. Rutherford also set up a detecting screen. This screen allowed him to see what directions the particles deflected in.
Although Rutherford made many great strides in the research of atomic structure, there were some holes in his research. Rutherford had built onto what earlier scientist had discovered but he did not find an answer for everything. One of the main holes in Rutherford’s theories was that he did not figure out what was holding the atom itself together. There was still more research to be done. Rutherford made a great impact but it was necessary for other scientists to continue where he left off.
Key Vocabulary Alpha Particles (noun): a helium nucleus emitted by some radioactive substances, originally regarded as a ray.
Deflect (verb): cause (something) to change direction by interposing something; turn aside from a straight course.
Ernest Rutherford’s Background
by Matt Schwarz & Morgan Spring
Ernest Rutherford was an English physicist of the early 1900’s. He was born in 1851 and he died in 1937. He was most well-known for the discovery of the nucleus in 1911. During Rutherford’s time, he worked with many other scientists. Some of these scientists were previous students of his at the University of Manchester. Prior to his world famous discovery, Rutherford transformed his thoughts and attention from radio chemistry to alpha, beta, and gamma rays in physics.
Rutherford’s Experiment Conducting Rutherford’s experiment used gold (the metal used to see if particles could go through it) sheets because the particles were more likely to go through thin sheets. In Rutherford’s experiment almost all of the particles went onto the screen placed behind the gold foil meaning it passed through the sheet of gold. Not all of the particles passed through the gold, those parts were deflected. The dense parts of the gold sometimes didn’t allow the particles to go through it. The heavy part of the atom was classified as the nucleus at the conclusion of Rutherford’s experiment. With the discovery of the nucleus, we are able to have a better understanding of atoms and where most of the mass comes from in an atom.
Was Rutherford’s Experiment Accurate? Rutherford’s experiment was well thought out and gave us good information. The experiment could’ve been less complicated in the sense that the technology of that time period was not highly developed. Rutherford was one of the greatest physicist of all time and his discoveries will be remembered and built upon for the rest of human existence.
Shakila Muhammad November, 2013
Who IS Niels Bohr? The discoveries of the electron and radioactivity at the end of the 19th century led to different models for the structure of the atom. In 1913, Niels Henrick David Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities.
WHAT DID HE DO? The Bohr model shows the atom as a small, positively charged nucleus surrounded by orbiting electrons which, he called the “Planetary Model�. Bohr was the first to discover that electrons travel in separate orbits around the nucleus and that the number of electrons in the outer orbit determines the properties of an element.
He used the electron configurations to find how many electrons were in an atom. Tellurium = 1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6,5s2,4d10,5p4,,,,,,
Noah Peterson and Brett Norris November 2013 Who is J.J. Thomson? Joseph John Thomson was born in a suburb of Manchester called Cheetham Hills on December 18, 1856. In 1876 he became a member of Trinity College and remained part of the school the rest of his life. In 1896 he visited America for the first time in his life. This is when his best work started coming out. He published a book in 1903 of some of the research he found in America. Thomson returned to America in 1904 to give 6 lectures at the University of Yale where he brought up some important suggestions on an atoms structure. This is when he created the plum pudding model.
The Plum Pudding Model When Thomson made the plum pudding model, he thought it was a sphere with a positive charge fluid in it. The fluid was called the “pudding” and scattered in it were electrons known as the “plum”. Thomson thought the positive charged fluid held negatively charged electrons because of electrical fields; however there was no define answer to this. Thomson’s experiment to discover the plum pudding model was having an anode at one end of a tube (+ charge) and a cathode at another end (- charge). He then put different chemical gases through them and saw the reaction it did.
What did he do? James Chadwick was searching for the missing particle that gave an atom its mass. Something besides the protons was giving an element its atomic mass. Scientists before Chadwick thought that electrons were found in the nucleus with protons. However, electrons have almost no mass. Chadwick was looking for a neutral particle and to determine the mass of the particle, he attacked Boron with alpha particles. He analyzed the interaction of neutral particles with nitrogen. He also tested this with other elements including Beryllium. How did he do it? To determine that this neutral particle was a neutron, he smashed alpha particles into Beryllium and the radiation was released hit another target, known as paraffin wax. Paraffin is a waxy substance made from distilling a complex mixture of decomposed organic matter. When the radiation of the Beryllium hit Hydrogen atoms of the wax, the atoms were transferred to a detecting chamber. The conclusion of his experiment showed that Beryllium atoms releasing massive neutral particles. These particles were neutrons, the hidden mass in atoms.
By Sarah Ha and Alicia Lovan
What happened? Chadwick's experiment was highly accurate. He showed that the nucleus was made up of protons and neutrons. However, he believed that the neutron was a proton-electron pairing. The protons gave mass and electrons gave the neutron no electrical charge. Werner Heisenberg would later show that the neutron was its
Physicist, James Chadwick, won many awards and prizes including the Nobel Prize for his discovery of the neutron. He was born on October 20th, 1891 and died on July 24th, 1974. Chadwick spent his lifetime in the United Kingdom. He worked with Ernest Rutherford, who discovered the nucleus of an atom. While working with Rutherford, Chadwick was able to distinguish the neutron. He retired in 1959.
own unique particle.
What was the significance? Why is Chadwick's discovery of the
Neutrons and protons are found in the nucleus and make up the atomic mass.
neutron important? Not only does is complete the make up of an atom, but it helped later scientists with other things as well. When neutrons are fired from a source, it can go through layers of certain materials and go into the nucleus of target atoms. Uranium was used to hit a target, this led to nuclear fission to be possible, which further resulting in nuclear weapons and power plants. Some say nuclear weapons help and hurt us. Regardless, without the discovery of the neutron, we would never know.
What is “plum pudding” model?
By Quynh Pham & Sa Nguyen
In this model, the atom is composed of electrons had proposed that atoms of electricity surrounded by a “soup” of positive charge to balance the electrons’ negative charges, like negatively charged “plums” surrounded by positively charged “pudding”. Also the electrons were free to rotate within the blob and free to rotate in rings which were further stabilized by interactions between the electrons.
Are there any problems in Thomson’s logic? The model was incorrect for many reasons. It could not predict why atom absorbed and emitted spectral lines. It didn't explain the neutrality of an atom nor did it explain why atoms undergo reactions. The real expect to the plum pudding model came from experiments showing that the atom have nucleus.
How is it important and impact on our society? It had marked the beginning of the atomic era of sciences. Scientists based on Thomson’s work, they created much more types of models that we know today. The indirect effects towards the world were quite tremendous. By understanding the proton and neutron system, mankind was able to synthesize different element for more uses.
“The atoms of the elements consist of a number of negatively electrified corpuscles enclosed in a sphere of uniform positive electrification.”
In 1896 J.J Thomson conducted an experiment called “The Plum Pudding Model,” designed to show that the pudding itself had a positive charge while the plums were the negatively charged particles. He wanted to see how many particles were negative and how they were arranged. The model shows how the electrons were dispersed throughout the “sphere”. Now we know that this theory is not true. In 1909 Rutherford proved the Plum Pudding to be wrong, he discovered the nucleus. After that discovery we now know that the Electrons aren’t just randomly there, they orbit an atom’s Nucleus. Overall Thomson’s experiment was kind of useful because if he hadn’t taken that step who knows how long anyone else was going to do it. Thankfully Rutherford did go over it, and corrected it. Although Thomson’s experiment was wrong, he discovered the Electron which made a great impact. All in all, many Scientists contributed in order to find every piece of the puzzle, and now we know the truth about Atoms.
While studying in the Cavendish, Ernest Rutherford became fascinated by radioactivity. He investigated it for twenty years, first at McGill University, Canada and then at the University of Manchester, before returning in 1919 to lead the Cavendish as its Professor. His most famous discovery took place while he was Professor at Manchester. In March 1911 Rutherford announced that each atom contains a positively charged nucleus. Investigations of these nuclei became known as 'nuclear physics'. Rutherford's discovery ultimately led to the 'splitting of the atom', more than twenty years later in the Cavendish. Rutherford proposed that the atom contained a massive nucleus containing all of its positive charge, and that the much lighter electrons were outside this nucleus. The nucleus had a radius about ten thousand times smaller than the radius of the atom, only ten femtometres, or one hundred thousand billionth of a meter! Scattering at large angles occurred when the alpha particles came near to a nucleus. The reason that most alpha particles were not scattered at all was that they were passing through the relatively large 'gaps' between nuclei. Rutherford revised Thomson's 'plum pudding' model, showing how electrons could orbit a positively charged nucleus, like planets orbiting a sun.
By: Ngoc Nguyen
The Discovery of the Nucleus
Discovering the Nucleus
By Josh Siefken & Matt Clarke
In 1910, the nucleus of an atom was discovered by Ernest Rutherford. He found this while conducting an experiment that demonstrated how alpha particles reflect when they hit gold foil. By the patterns that the reflected particles made, he deducted that there must be empty space in atoms, because many of them went straight through the foil.
Impact on the Atomic Model Before this, the atomic model didn’t include any space, as JJ Thomson’s model (the plum pudding model) included electrons mixed in with the rest of the atom, but there was no evidence that an atom wasn’t one solid mass. This groundbreaking discovery made the Atomic Model much more true to what it is today, and vastly improved our understanding of the atom.
Rutherford’s atomic model (left) next to Thomson’s Plum pudding model (right)
Atom: The basic unit of all matter. Different types of atoms (different numbers of protons, and different atomic numbers) make up different elements. Nucleus: The center of an atom, made up of protons and neutrons. Atomic Model: The model of what people think an atom looks like. This includes the nucleus, the electron cloud, and the electron configuration of different atoms
Background
BY: Diana Rodriguez, Allyson Jorgensen, Melonie Chipp
Ernest Rutherford was born in Brightwater, New Zealand on August 30th, 1871.He Cambridge University in England also known as United Kingdom. In 1908 he won the Nobel Prize in chemistry and had many significant discoveries to his credit. In 1911 Rutherford discover the nucleus by using JJ Thomson’s model and recomposing his experiment. On October 19th, 1937 Ernest Rutherford died in Cambridge, United Kingdom, at the age of 66.
The Gold Foil Experiment In 1911, Ernest Rutherford performed an experiment to test out J.J. Thomson’s plum pudding model of the atom, also known as the “Gold-Foil” experiment. Here is a list of supplies Rutherford used in his experiment: Particle Emitter A 1/3000 of an inch thick piece of gold foil Detection screen
Like it shows in the picture, he set up the particle emitter right where the opening of the detection screen was. Next he securely placed a thin piece of gold foil right in the center of the detection screen and made it parallel to the particle emitter. The emitter fired a beam of alpha particles directly vertical to the gold foil. Based off of J.J. Thomson’s plum pudding model, a cloud of positive charges with a few negative charges, Rutherford thought that all the alpha particles would go straight through the foil. Instead some of the particles deflected as if they hit something hard. With this discovery, Rutherford was able to figure that there was a nucleus in the center of the atom.
How has it helped society? Originally JJ Thomson’s proposed the plum pudding model. It showed electrons and protons distributed through the space of an atom. Rutherford conducted the “Gold-foil” experiment which discarded Thomson’s model. Rutherford reasoned the only way the alpha particles could have deflected is if most of the atoms mass was in the nucleus. The discovery of the nucleus was a major step towards the atomic model we have today. Nucleus of an Atom: Extremely small, positively charged, dense center of an atom that is Holes in Rutherford’s Theory compose of protons and neutrons. Although Rutherford discovered the nucleus, his model wasn’t complete. His model didn’t get into detail about how the Alpha Particles: A particle composed of two electrons occupied the surrounding of the nucleus. His theory protons and two neutrons identical to a helium showed that the electrons just circled around the nucleus. If this really happened, the electrons would collide which would make nucleus. the atom unstable. In the Quantum Mechanic Atomic Model that we use today the electrons really orbit around the nucleus in a specific order just like the planets around the sun. The low energy electrons would be the closest to the atom and the higher energy electrons would be the farthest away.
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