Stephanie+Young

1. History of the Atom (5pts) 2.Atomic Structure (5pts) For a bonus point:
 * Find out the important scientists who contributed to our current knowledge of the atom. Include:
 * A picture.
 * When they lived.
 * What they did.
 * Find out the important experiments that were used to make breakthrough discoveries.
 * Who perfomed these experiments?
 * Include years of each discovery/experiment so we can get an idea of how long this process has taken.
 * What are the different parts of the atom?
 * What are the different particles that make up the atom?
 * Where are they located?
 * What makes atoms of different elements different?
 * 1) Add an APPROPRIATE comment to someone's page through the discussion tab.



<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">1. **History of the Atom**

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 40.5pt; text-indent: -0.25in;">__Important Scientists:__

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">1. J.J. Thomson <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">2. John Dalton <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">3. Ernest Rutherford <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">4. Niels Bohr

1.J.J. Thomson In 1897, British scientist discovers the electron. He was alive from 1856 - 1940, and died at the age of 84. He made an atomic model, in which negatively charged electrons are embedded in a sphere of positive electric charge.

2.John Dalton He lived from 1766 - 1844, and died at the age of 78. In 1803, he suggested that atoms are tiny, solid, indestructible spheres, with no internal structure.

3.Ernest Rutherford He was alive from 1871 - 1937 In 1911,he stated that an atom has a dense, positively charged nucleus. Electrons move randomly in the space around the nucleus.

4.Neil Bohr In 1913, he presented a model in which electrons move in circular orbits at fixed distances from the nucleus. This is basically the model we accept today, but some important discoveries came after him, such as the electron cloud model and the neutron.

__<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Important experiments __

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">- In the 1800’s, __John Dalton__ performed experiments with chemicals that showed that matter seemed to consist of elementary lumpy <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">particles (atoms). <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">- In 1900, __Max Planck__, who was a professor of theoretical physics in Berlin, showed that when you vibrate atoms strong enough, you can measure <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">the energy. He called these energy packets, quanta. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">- In 1911, __Ernest Rutherford__ thought it would be interesting to flood atoms with alpha rays, figuring that this experiment could investigate the inside of <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">an atom. He used Radium as the source of the alpha particles and shinned them onto the atoms in gold foil. Behind the foil lay a fluorescent screen in <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">which he could observe the alpha’s impact. His observation was unexpected. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">- Somewhere between 1896 and 1904, __Joseph John Thomson__ discovered a method for separating different kinds of atoms and molecules by the use <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">of positive rays. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 0.75in;">- In 1912, __Niels Bohr__ came up with a theory that said the electrons do not spiral into the nucleus like thought in previous years.

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt;">2. **Atomic Structure**

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 41.25pt; text-indent: -0.25in;">The different parts of the atom: <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 59.25pt; text-indent: -0.25in;">- Protons: positively - Electrons: negative -Neutrons: no charge

<span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 59.25pt; text-indent: -0.25in;">There are two main parts to an atom- the //__nucleus__// and //__the area surrounding the nucleus.__// <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 59.25pt; text-indent: -0.25in;">- Protons and Neutrons are in the nucleus <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 59.25pt; text-indent: -0.25in;">- Outside the nucleus, electrons are found moving around at different energy levels,which is an **//__electric cloud.__//** <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt 59.25pt; text-indent: -0.25in;">- Depending on what the atom is making up, there are numerous combinations for how many of each there are. <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 10pt 59.25pt; text-indent: -0.25in;">- Protons and neutrons, which are called nucleons when they’re found in an atomic nucleus, are further made up of even smaller subatomic particles.

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