History and Models of the Atom Pages 89 - 97 The Billiard Ball Model proposed by John Dalton in 1804 this theory proposed that matter was composed of small, spherical particles but evidence was later gathered that
matter was composed of even smaller bits in the 1900s evidence was discovered regarding charges: atoms have positive and negative parts charges interact:
as a result, revisions to Daltons model had to be made Chocolate Chip Cookie Model using available data on the atom, J.J. Thompson came up with the idea of having charges embedded with Daltons Billiard Balls
positive (evenly distributed) dough part negative chocolate
note: this model kept Daltons key ideas intact Nuclear Model Ernest Rutherford discovered a huge flaw in the previous concept of the atom during his now famous gold foil experiment for experiment setup
see figure 4-11 (page 95) Nuclear Model if previous models were correct alpha particles would have passed straight through the the gold Nuclear Model
Rutherford found that most (99%) of the alpha particles that he shot at the gold went straight through - + -
- Nuclear Model from these experiments Rutherford concluded that the atom had a dense positive core, with the rest composed of mostly empty space with the occasional negatively charged electron
note: this model completely changed the definition of atom Nuclear Model Rutherford could not explain why the nucleus did not explode due to repulsion it was not until 1932 that the neutron was discovered, which helps counteract
the positive repulsion Bohr Model Niels Bohr proposed that electrons revolve around the central positive nucleus (like planets in the solar system) negative electrons
3 positive protons Bohr Model Bohr also suggested that the electrons can only revolve in certain orbits, or at certain energy levels (ie, the energy levels are quantized) no energy level in between steps
Quantum Mechanical Model the current understanding of the atom is based on Quantum Mechanics this model sees the electrons not as individual particles, but as behaving like a cloud - the electron can be anywhere in a certain energy level
Quantum Mechanical Model electrons can be found anywhere in these shells note: the electrons are still quantized no electrons can
be found here Note About Chem 11 most things we do can be explained using Daltons and/or Bohrs model the Quantum Mechanical model, although most accurate, is complex even at a university level (conceptually
and mathematically) and will not be discussed here
equal to 1000C; the rolling speed was . taken equal to 3 m/s, friction . coefficient 0.3, and friction factor 0.7. Assumptions: The join between the core and cladding layer adhered closely. Thermal conductivity between rolls and material is the...
This presentation is based on content presented at the Mines Safety Roadshow held in October 2009 It is made available for non-commercial use (e.g. toolbox meetings) subject to the condition that the PowerPoint is not altered without permission from Resources...
St Philip Neri "Third Apostle of Rome" 1533, moved to Rome from Florence in 1533. Ministered to poor, needy, prostitutes. 1548, Founded the Confraternity of the Most Holy Trinity to minister to pilgrims
Urea Synthesis Process. Urea is produced from carbon dioxide and ammonia and composed of two chemical reversible reactions. 2NH. 3 + CO 2 NH 4 COONH 2 . (-28.4 Kcal/ Mole). NH. 4 COONH 2 NH 2 CONH 2 +...
Slide 1d Spiritual Development Develop an inner discipline and training. Be involved in corporate (group) activities. Understand the natural world around you. Help to create a more tolerant and caring society. Discover the need for prayer and worship.
Hasta 1913 Santander y Cundinamarca fueron los principales productores. Estas semillas habrían permitido la presencia de café en los departamentos de Santander y Norte de Santander, en el nororiente del país, con su consecuente propagación, a partir de 1850, hacia...
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