• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

The history of the atom

Extracts from this document...

Introduction

[Type text] Shafaq Zahid The history of the atom Over the span of hundreds of years science has advanced tremendously improving our understanding of what makes up the world we live in. The atom is one of sciences important findings and has had a changing history of new discoveries, always altering the way we see things. In the early 1800s a man called John Dalton made an atomic theory with predictions about atoms. He stated that atoms are tiny particles that make up elements and that they are indivisible. We now know that there are in fact smaller particles inside the atom, but at this stage it was assumed that the atom was the smallest. ...read more.

Middle

As the years went on a scientist called JJ Thomson discovered the electron by using cathode ray tubes. This discovery proved that there was an even smaller particle inside the atom itself, disproving one of Dalton?s theories and improving our understanding about elements and atoms. JJ Thomson created the famous plum pudding atom model which shows an atom made up of negative electrons moving about in a ?sea? of positive charge, thus making the atom neutral with no overall charge. His discovery of the electron advanced atomic theories massively. In 1909 the scientist, Ernest Rutherford conducted an experiment in which he fired alpha particles (positive) ...read more.

Conclusion

Eventually in 1932 James Chadwick discovered the uncharged particles called neutrons, subsequent to studies of a new type of radiation emitted after bombarding light elements with high energy and particles. The neutron doesn?t really affect the properties of the atom, it just adds to the mass. So, the atom was thought of as being indivisible when studies began but as time went on and science progressed, 3 new particles: electrons, protons and neutrons were discovered. Different theories had been disproved along the way but some are still believed to this day. Further developments may sprout another discovery in the future, altering our model of the atom once again. It is thought that protons and neutrons could be made up of smaller particles named quarks but this is just a theory! ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Physical Chemistry section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

3 star(s)

Mark: 3/5
This essay is strong when reporting experimental findings but the theme of the essay is lost. The paragraphs do not link with the topic, and the conclusion is factually inaccurate. Some sentence constructions are poor and with further amendments this essay could reach 4/5.

In order to reach 5/5 this essay would need to have significantly more detail. The idea of the atom did not start with John Dalton, so it would have been nice to have a little bit more background there.

Marked by teacher Kathryn Bradley 24/09/2012

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Physical Chemistry essays

  1. Marked by a teacher

    Revision notes - Test For Gases and Ions

    4 star(s)

    It should decompose producing the oxide and carbon dioxide. E.g. Test for the gas using limewater solution. Limewater should turn from colourless to cloudy in the presence of carbon dioxide due to precipitation of calcium carbonate. Test 2 Add dilute HCl to the solid.

  2. The citric acid cycle has been described as "the hub of the metabolic wheel". ...

    to 4 carbon oxaloacetic acid. NADH2 is formed in the process. Thus, oxaloacetic acid is regenerated in the last step. It can combine with another 2 carbon Acetyl Co-A to form citric acid and participate in the citric acid cycle again.

  1. Drug: Antacid Effectiveness Analysis To determine the neutralizing ability of antacids in different ...

    react together to form a water molecule H2O. In the process, a salt is also formed when the anion from acid and the cation from base react together. Neutralization reactions are generally classified as exothermic since heat is released into the surroundings.

  2. An Investigation using Chromatography to determine the different Amino Acids

    The proteins in an egg white are globular proteins, which means that the long protein molecule is twisted and folded and curled up into a more or less spherical shape. A variety of weak chemical bonds keep the protein curled up tight as it drifts placidly in the water that surrounds it.

  1. The purpose of this experiment was to isolate and characterize macromolecules.

    All steps were followed with no deviation in procedure. Results: Table 1 - Proteins Protein Distance Travelled by Substance (cm) Distance Travelled by Solvent (cm) Rf Value Unhydrolyzed Protein (a) 1.4 6.5 1.4/6.5 = 0.22 (b) 3.6 6.5 0.55 Hydrolyzed Protein (a) 0.7 6.5 0.48 (b) 3.3 6.5 0.51 (c)

  2. Identification of amino acids by using paper chromatography

    * The following procedure was repeated for the other two lines so that the opposite edges of the paper almost met to form a square cross-section. * The paper was held by the edge furthest from the start line, and was placed in a beaker so that it does not touch the sides.

  1. AQA As Applied Science Unit 3. Colorimetry experiment on Ribena juices

    Put water in until it reaches the mark 5. Measure the Ribena juice and the distilled water 6. Put a sample of pure distilled water in to the curette and set to zero 7. Pour the Ribena juice and distilled water in to the Graduated flask 8. Close the top of the volumetric flask and shake them together so that the Ribena juice and distilled water mix 9.

  2. The main purpose of this investigation is to test and analyse Mummion. By doing ...

    2.4.2 Risk assessment Title of investigation: Name: Place: A preservative for mummies Teresa Hollomon Writhlington school Outline of the procedure: Part 1: purification of the Mummion In a beaker we had the Mummion crystals, we would then add distilled water to fry and separate the impurities from the solution.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work