History of the Atom Activity. Warm - Up Make a square using the puzzle pieces on your desk You...
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Transcript of History of the Atom Activity. Warm - Up Make a square using the puzzle pieces on your desk You...
History of the Atom Activity
Warm - Up
• Make a square using the puzzle pieces on your desk
• You discover a missing piece to the puzzle. Work by yourself to fit the piece in and make a new square.
• How does this relate to making a discovery in science?
Objective
Homework
• Review History of the Atom PowerPoint on my website, fill in gaps of information
Agenda
• Warm – Up• Review Mole HW• History of the Atom Research• Construction of Timeline• Gallery Walk• Exit Ticket
• Working in groups of 4 (6 groups)– 1 computer per group– Class set of textbooks
• Each person will be assigned four scientists to research
• Research the scientist• Complete chart• Share information with the group• Construct a timeline of for the history of the atom
Project Format
• Name of Scientist• Their Accomplishment– Regarding the atom– Development of the atom
• Date of discovery• Picture of the experiment (if there is an experiment) – – Explain what they found in their experiment
• Picture of the model of the atom constructed (if there is a picture available)– What is the model of the atom showing?
What to Research
History of the Atom Notes
Democritus (400 BC)
• All matter is composed of tiny, indivisible parts called atoms
• Said they could not be divided any further
John Dalton (1803)
• Dalton’s Atomic Theory• All matter is composed of tiny indivisible parts called
atoms (they can be broken down further, although properties will not be retained)
• Atoms of the same element are exactly alike, atoms of different elements are different (not all atoms of the same element have the same mass – isotopes)
John Dalton (1803)
• Atoms can combine in simple ratios to form compounds
• Atoms are neither created nor destroyed - Atoms cannot be destroyed, they simply rearrange in a chemical change, therefore the total amount of atoms remains the same
John Dalton (1800’s)
J.J. Thomson (1897)
• Plum Pudding Model of the Atom• Discovered the electron• Worked with Cathode Ray Tubes• Discovered particles with a negative charge,
electrons – knew they were negative charges by the deflection of the beam from a magnet
• “Pudding” is positive
J.J. Thomson (1897)
J.J. Thomson (1897)
• Discovered that the beam going between the anode and cathode could be deflected by bringing a magnet close to the cathode ray tube. The deflection that Thomson observed showed that the beam must have been made up of negatively charged particles
Ernest Rutherford (1911)
• Gold Foil Experiment – worked with alpha particles• Discovered that atoms have a nucleus
Ernest Rutherford (1911)
Niels Bohr (1914)
• Electrons occupy different fields or energy levels• Based on the fact that atoms appeared to release
fixed amounts (quantized) of energy when exposed to heat
• When an electron is exposed to an energy source, it jumps to a higher energy level
• When the electron eventually falls back to its original position, energy is released
Niels Bohr (1914)
Niels Bohr (1914)
• Start of the Quantum Mechanical Model• Electrons are particles
Louis de Broglie (1924)
• Posed the question, “If light can be viewed in terms of both “wave” and “particle” properties, why can’t particles of matter, like electrons, be treated the same way?”
• His question/idea was later proved to be correct
Erwin Schrödinger (1926)
• Shows where electrons will probably be found by using the waves they leave behind
• Electrons are waves• Update to the Quantum Mechanical Model• Sometimes called the Electron Cloud Model
Erwin Schrödinger (1926)
Final Thought
• No model of the atom perfectly describes the behavior of subatomic particles
• It is difficult to come up with an analogy, because…
• The only thing that behaves like an atom is an atom
Exit Ticket