Atomic Theory Assignment help at HelpWithAssignment.com
Atomic Theory Assignment help at HelpWithAssignment.com
Atomic Theory Assignment help at HelpWithAssignment.com
Atomic theory is the theory of matter, which states that matter is comprised of discrete units called atoms. In the 19th century in the field of chemistry found evidence that matter indeed behaved as if it were made up of particles.
The word atom is derived from the ancient Greek adjective atomos, 'undivisible') was applied to the basic particle that constituted a chemical element, because the chemists of the era believed that these were the fundamental particles of matter.
John Dalton studied and expanded and developed the law of multiple proportions: if two elements can together form more than one compound, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small integers.
Dalton also believed atomic theory could explain why water absorbed different gases in different proportions: for example, he found that water absorbed carbon dioxide far better than it absorbed nitrogen. Dalton hypothesized this was due to the differences in mass and complexity of the gases' respective particles. Indeed, carbon dioxide molecules (CO2) are heavier and larger than nitrogen molecules (N2).
Dalton proposed that each chemical element is composed of atoms of a single, unique type, and though they cannot be altered or destroyed by chemical means, they can combine to form more complex structures (chemical compounds). This marked the first truly scientific theory of the atom, since Dalton reached his conclusions by experimentation and examination of the results in an empirical fashion.
Atoms were thought to be the smallest possible division of matter until 1897 when J.J. Thomson discovered the electron through his work on cathode rays. Through experimentation, Thomson discovered that the rays could be deflected by an electric field (in addition to magnetic fields, which was already known). He concluded that these rays, rather than being a form of light, were composed of very light negatively charged particles he called "corpuscles" (they would later be renamed electrons by other scientists).
Thomson believed that the corpuscles emerged from the molecules of gas around the cathode. He thus concluded that atoms were divisible, and that the corpuscles were their building blocks. To explain the overall neutral charge of the atom, he proposed that the corpuscles were distributed in a uniform sea of positive charge; this was the plum pudding model as the electrons were embedded in the positive charge like plums in a plum pudding.
The gold foil experiment
In the gold foil experiment, he shot alpha particles at a thin sheet of gold, measuring their deflection with a fluorescent screen. Given the very small mass of the electrons, the high momentum of the alpha particles and the unconcentrated distribution of positive charge of the plum pudding model, he expected all the alpha particles to pass through the gold sheet without significant deflection. To his astonishment, a small fraction of the alpha particles experienced heavy deflection.
This led Rutherford to propose a planetary model in which a cloud of electrons surrounded a small, compact nucleus of positive charge. Only such a concentration of charge could produce the electric field strong enough to cause the heavy deflection.
While experimenting with the products of radioactive decay, in 1913 radio chemist Frederick Soddy discovered that there appeared to be more than one element at each position on the periodic table. The term isotope was coined by Margaret Todd as a suitable name for these elements.
That same year, J.J. Thomson conducted an experiment in which he channeled a stream of neon ions through magnetic and electric fields, striking a photographic plate at the other end. He observed two glowing patches on the plate, which suggested two different deflection trajectories. Thomson concluded this was because some of the neon ions had a different mass. The nature of this differing mass would later be explained by the discovery of neutrons in 1932.
The topics that we deal with usually apart from other topics are
Mole Concept, Chemical Equation, Atomic Theory, Organic Chemistry, Inorganic Chemistry, Nuclear Chemistry, Periodic Table, Energetics, Chemical Equilibrium, Electrochemistry, Chemical Kinetics, Solid State, Surface Chemistry.
At HelpWithAssignment.com we offer the best help in assignments, homework and online tutoring in Chemistry apart from other subjects. Our tutors are professionals and experts in their fields which include subjects like Statistics, Finance, Economics, Marketing, Human Resources, Engineering, Mathematics, Physics, Biology, English and other subjects. All these services are provided 24/7. So, any time of the day or night, one can just count on us for academic help.
We provide assistance to students from K-12, College and University. The prices that we quote are moderate and the quality that we provide is the best quality. Our work has 0% plagiarism in it. We do not resell our work i.e. an assignment sent to one student will not be sent to another student who wants help on the same topic. Instead, we start working on the topic from scratch and give the student a new assignment. This is the reason why 90% of our students come back to us.
Visit our website http://www.helpwithassignment.com/ http://www.helpwithassignment.com/chemistry-assignment-help for further details.
King Solomons announces progressive jackpot win How to Make a Slideshow the Easy Way Are Algal Blooms Becoming Worse? Chemical Equations Assignment Help at HelpWithAssignment.com Flexible Transistors Nashville Pressure Washing UPS Spares Enhance Durability of UPS Cataclysm Stat Change Confusion Pearly Papules Removal Scottish Clay Shooting How To Prepare For Bootcamp Top Gear episodes: In a class of its own!! The Importance Of Directory Submission For Seo