Presentation is loading. Please wait.

Presentation is loading. Please wait.

Unit 2: Atoms.

Similar presentations


Presentation on theme: "Unit 2: Atoms."— Presentation transcript:

1 Unit 2: Atoms

2 Scientists to Know … CHADWICK THOMSON RUTHERFORD DEMOCRITUS BOHR
HEISENBERG DALTON

3 The History of Discovering the Atom
The Timeline of Discovery The Intermediate Atomic Models Philosophical Era Alchemical Era Classical Era Subatomic Era Modern Era For later study… Uncuttable Model 3. The Dalton Sphere Model 4. The Plumb Pudding Model The Planetary Model 5. The Quantum Model

4 The Philosophical Era (Circa 500~300BCE)
Brainstorm about this era? This is a good era to do before Chapter 4 officially begins The Philosophical Era (Circa 500~300BCE)

5 The Philosophical Era (Circa 500~300BCE)
A time when logic ruled the land… This is a good era to do before Chapter 4 officially begins The Philosophical Era (Circa 500~300BCE)

6 Philosophical Era (Ancient Greece)
Their ideas were based on logic, without experimental support (as was common in that time) Age of Thinking

7 Philosophical Era Democritus ( BCE) Argued that matter was made of small, indivisible particles Called the small particles “atomos” meaning “that which cannot be divided” Believed properties of matter came from the properties of the “atomos”

8 Alchemical Era (300 BCE ~ 1400CE)
Brainstorm about this era? This is another good era to do before Chapter 4 officially begins Alchemical Era (300 BCE ~ 1400CE)

9 Alchemical Era (300 BCE ~ 1400CE)
The “Dark Ages” of Chemistry where early chemists had to work in secret and encode their findings for fear of persecution This is another good era to do before Chapter 4 officially begins Alchemical Era (300 BCE ~ 1400CE)

10 Alchemical Era Alchemy the closest thing to the study of chemistry for nearly two thousand years Very mystical study and experimentation with the elements and what was perceived as magic Study was illegal, findings hidden in code

11 Alchemical Era Elements in Alchemy Alchemists studied many different materials, and their properties, in order to find a way to turn lead into gold and achieve immortality

12 The Classical Era (1400CE – 1887CE)
Brainstorm about this era? ------This is a good section to do with Chapter 4, sections 1&2 (students read those simultaneously) The Printing Press was invented in Germany, and this lead to the widespread transfer of knowledge in Europe. Other regions were more geographically restricted from this technological advancement. The Classical Era (1400CE – 1887CE)

13 The Classical Era (1400CE – 1887CE)
The printing press brings the widespread transfer and acquisition of knowledge ------This is a good section to do with Chapter 4, sections 1&2 (students read those simultaneously) The Printing Press was invented in Germany, and this lead to the widespread transfer of knowledge in Europe. Other regions were more geographically restricted from this technological advancement. The Classical Era (1400CE – 1887CE)

14 John Dalton [really famous] (1766-1844)
Classical Era John Dalton [really famous] ( ) Dalton returns to Democritus’ ideas in 1803 with four arguments All matter is made up of tiny particles called atoms All atoms of a given element are identical to one another and different from atoms of other elements Atoms of two or more different elements combine to form compounds. A chemical reaction involves the rearrangement, separation, or combination of atoms. Atoms are never created nor destroyed during a chemical reaction. John Dalton The Atom

15 The Subatomic Era (1897CE – 1932CE)
Brainstorm about this era? This is a good era to do with Chapter 4, section 3 The Subatomic Era (1897CE – 1932CE)

16 The Subatomic Era (1897CE – 1932CE)
The relatively quick discovery of things smaller than the once “indivisible” atom - EXPERIMENTAION This is a good era to do with Chapter 4, section 3 The Subatomic Era (1897CE – 1932CE)

17 Subatomic Era JJ Thomson Use the cathode ray tube (glass chamber used to study electricity in gasses) to discover the electron.

18 Subatomic Era J.J. Thompson English (1897) Put magnetic fields near cathode rays (CRT) Using three different arrangements of CRTs he was able to determine that the Cathode rays… Were streams of negatively charged particles Those particles had very low mass-to-charge ratios Mass-to-charge ratio of Electron: ×1011C/kg Mass-to-charge ratio of Proton (H+):9.578×107C/kg The schematic depiction of the CRT given here is one of only three types of CRTs that Thompson experimented with. He needed all three types to collect the data needed to get the information he presented. Also, the particular schematic shown here is also a rudimentary schematic for any CRT television. An interesting talking point for students, who may have some experience with the latter.

19 The First Subatomic Particle
Subatomic Era The First Subatomic Particle Electrons – one part of an atom with one negative charge Since atoms were known to be electrically neutral, Thompson developed the plum pudding model of the atom Negatively (-) Charged electrons Positively (+) charged majority

20 Ernest Rutherford New Zealander (1910)
Subatomic Era Ernest Rutherford New Zealander (1910) Rutherford worked with radiation and had heard of Thompson’s plumb pudding model He wanted to use radiation to prove Thompson’s model With the help from Marie Curie, he shot alpha particles (+) at an ultra-thin piece of gold foil, with a Geiger counter on the other side This is another good break to comment on the diversity of people in science. Marie Curie was a BIG DEAL. She had 2 Nobel prizes to be proud of. Ernest Rutherford New Zealand Marie Curie Polish/ French

21 Rutherford’s Results Rutherford’s results were not what he expected
Subatomic Era Rutherford’s Results Rutherford’s results were not what he expected Expected to have all alpha particles (+ charge) go straight through all of the atoms Saw that occasionally an alpha particle would ricochet Determined the positive charge of an atom must be held in a massive, centrally located, “nucleus”

22 The Second Subatomic Particle
Subatomic Era The Second Subatomic Particle After more experiments the second subatomic particle was formally named (1911) Proton Proton: The massive subatomic particle, within the nucleus of an atom, with a single positive charge

23 Subatomic Era The Planetary Model (1911) Earnest Rutherford took his idea of a nucleus, and the known electrons, to construct a new atomic model Compact nucleus With a positive center The orbit of the electrons kept them from falling directly into the nucleus, just like planetary motion The Rutherford Model or The Planetary Model The image shows a distinction between two types of particles in the nucleus. Rutherford’s model technically would not have had this – or even possibly known about neutrons. In fact, Rutherford's model was kind of vaguely described even in the article he used to propose it – he was very leery of committing to more than what he absolutely knew to be true about the atom. (He never even said “electron orbits.” That idea was just pieced together from commentary on Rutherford’s model and what came after it.) You can raise questions as to why that may have been a good move…

24 The Third Subatomic Particle
Subatomic Era The Third Subatomic Particle Missing mass in the nucleus James Chadwick – determined that a another subatomic particle must be in the nucleus with the protons Called this subatomic particle: neutron because it has NO charge. James Chadwick English

25 The Modern Era (1900CE – Present)
Brainstorm about this era? Comment on the scope of the course, and how chemistry is distinct from other “nearby” physical sciences. The Modern Era (1900CE – Present)

26 The Modern Era (1900CE – Present)
The Quark Era starts in 1964, but that advance can be regarded as outside the realm of chemistry – instead a part of nuclear physics Comment on the scope of the course, and how chemistry is distinct from other “nearby” physical sciences. The Modern Era (1900CE – Present)

27 Bohr’s Planetary Model of the Atom
Modern Era Bohr’s Planetary Model of the Atom integrated all known information into a new, math based, model of the atom He kept electrons in energy levels or fixed orbits around the nucleus Niels Bohr Danish Physicist

28 The Modern (current) Atom
Modern Era The Modern (current) Atom Uncertainty Principle An electrons position, momentum, energy and time can never be known at the same time. Electrons are so small and relatively massless to measure it becomes impossible because any measuring technique causes it to change position / move. Werner Heisenberg Germany

29 Modern Era What does it look like? Likely electron locations are now represented as clouds or orbitals (bubbles) Electron Clouds Electron Bubbles


Download ppt "Unit 2: Atoms."

Similar presentations


Ads by Google