ATOM
STRUCTURE
Electrons are negatively charged sub-atomic particles. It keeps moving out of the nucleus of the atom.
Protons are positively charged particles located in the nucleus of the atom.
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Neutrons are neutral subatomic particles. It is also located in the nucleus
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Nucleus is at the center of the atom
MODELS
Nuclear model – dense, positive nucleus surrounded by negate electrons
Planetary Model electrons of atoms are limited to a certain circular orbit around the nucleus. Similarly to the planets orbiting the Sun.
Plum pudding model a positive charge sphere with a few negatively charged particles, scattered in the sphere like raisins.
Neutron model atoms had their mass and positive electric charge concentrated in a very small nucleus.
Wave Model/Quantum Mechanical Model demonstrates that electrons are just as much a wave of energy as they are particles.
Solid Sphere Model a solid, indivisible sphere. Unable to destroy or reconstruct.
EARLY CONCEPTS AND DEVELOPMENT
1807
Based on British school teacher John Dalton theory on the other experimental data, atom is a uniform, solid sphere like billiard ball.
1911
Ernest Rutherford established that atoms have nuclei and discovered the nucleus was dense, positive charge in the center of the the atom
400 BC
Democritus proposed the first atomic structure. He proposed that matter composed of tiny indivisible particles
1913
Neils Bohr was able to develop the atomic model by relying on electron studies. He made a borh model that portrays electrons orbiting the nucleus.
1903
J.J Thomson discovered the electron by experimenting cathode ray tube and demonstrated that the cathode ray tubes were negatively charged particles within the atom.
1926
Erwin created the wave equation that helped the quantum model and he stated that electrons do not move in set paths around the nucleus but in wave.
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REFERENCES:
Paint valley local schools (n.d). Timeline of the atom. Retrieved from http://www.paintvalleylocalschools.org/Downloads/timeline-of-the-atomPPT.pdf
IntLink Education. (2019, January 17). A Timeline of Atomic Models. Medium. Retrieved from https://medium.com/@Intlink.edu/a-timeline-of-atomic-models-cb2607b1da85