Chemistry Science 10 History of the Atom. Atomic Theory Answer the following questions How long has...
-
Upload
gwendolyn-carr -
Category
Documents
-
view
220 -
download
0
description
Transcript of Chemistry Science 10 History of the Atom. Atomic Theory Answer the following questions How long has...
ChemistryChemistryScience 10Science 10
History of the AtomHistory of the Atom
Atomic TheoryAtomic Theory Answer the following questionsAnswer the following questions
• How long has the Atomic Theory been How long has the Atomic Theory been around?around?
• Is the Atomic Theory the work of one Is the Atomic Theory the work of one scientist?scientist?
• Have there been many changes to the Have there been many changes to the Atomic Theory?Atomic Theory?
• Do you think we fully understand atomic Do you think we fully understand atomic behaviour?behaviour?
History of the AtomHistory of the Atom Began with Began with
DemocritusDemocritus
Theory continually Theory continually tested and refined tested and refined through history through history until we have the until we have the current modelcurrent model
DemocritusDemocritus 460-370BC460-370BC Greek PhilosopherGreek Philosopher Pictured the atom Pictured the atom
as a solid sphere – as a solid sphere – hypothesised that hypothesised that there was a piece there was a piece of matter that of matter that could no longer be could no longer be divided in twodivided in two
No real scienceNo real science
John DaltonJohn Dalton 1766-18441766-1844 Hypothesised that Hypothesised that
there was a building there was a building block of matterblock of matter
Gave it the name of an Gave it the name of an atomatom
Basically, he restated Basically, he restated Democritus’s Theory Democritus’s Theory based on scientific based on scientific observationobservation
John Dalton’s TheoryJohn Dalton’s Theory Matter was composed of atomsMatter was composed of atoms Atoms of the same type all had Atoms of the same type all had
similar masssimilar mass A pure substance would contain the A pure substance would contain the
same type of atomssame type of atoms Compounds were different types of Compounds were different types of
atoms combined togetheratoms combined together Chemical reactions were the Chemical reactions were the
rearranging of compoundsrearranging of compounds
JJ ThompsonJJ Thompson 1856-19401856-1940 Used electron beam Used electron beam
directed at the atom to directed at the atom to test behaviourtest behaviour• Discovered that cathode Discovered that cathode
rays were streams of rays were streams of electrons (negative electrons (negative particles)particles)
Discovered there are Discovered there are both positive and both positive and negative particlesnegative particles
JJ Thompson’s TheoryJJ Thompson’s Theory ““Raisin-Bread” Model of Raisin-Bread” Model of
the Atomthe Atom• Solid mass of positive Solid mass of positive
charge (bread)charge (bread)• Random electrons with Random electrons with
negative charge negative charge throughout (raisins)throughout (raisins)
Attempted to predict Attempted to predict number of electrons number of electrons using electrostatic using electrostatic forcesforces
Ernest RutherfordErnest Rutherford 1871-19371871-1937 Set out to test Set out to test
Thompson’s ModelThompson’s Model Used alpha Used alpha
particles particles (radioactive) (radioactive) directed at Gold Foildirected at Gold Foil
Proposed the Proposed the Nuclear Model of Nuclear Model of the atomthe atom
Ernest Rutherford’s ModelErnest Rutherford’s Model All atoms would have All atoms would have
a positive nucleusa positive nucleus• 99.9% of atom’s mass99.9% of atom’s mass• Only .1% of atom’s Only .1% of atom’s
sizesize Atoms would have Atoms would have
orbiting electrons orbiting electrons (like planets)(like planets)
Majority of the atom Majority of the atom is empty spaceis empty space
Neils BohrNeils Bohr 1885-19621885-1962 Tested planetary orbital model of atomTested planetary orbital model of atom Used Hydrogen spectra for analysisUsed Hydrogen spectra for analysis
Neils Bohr’s ModelNeils Bohr’s Model Discrete energy Discrete energy
levels in which levels in which electron can existelectron can exist
Electrons can move Electrons can move between levels but between levels but never have a non-never have a non-whole number whole number energy levelenergy level
Quantization of Quantization of energyenergy
Quantum Mechanical ModelQuantum Mechanical Model No longer No longer
individual scienceindividual science Teams work Teams work
together to solve together to solve problemsproblems
Current model Current model explains why the explains why the periodic table periodic table worksworks
Quarks & LeptonsQuarks & Leptons Newest theoryNewest theory Quarks make up Quarks make up
protons and protons and neutronsneutrons
Electrons are Electrons are another type of another type of matter called matter called leptonsleptons
Bosons create Bosons create forcesforces