a history of chemistry
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A history of chemistry. “Old dead guys”. It all started back when…. 400 BC- Democritus- first to come up with the idea that things are made of “atoms”. Skip to. 1803- John Dalton Proposed the atomic theory. Next was. 1869- Dmitri Mendeleev - PowerPoint PPT PresentationTRANSCRIPT
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A history of chemistry
“Old dead guys”
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400 BC- Democritus- first to come up with the idea that things are made of “atoms”
It all started back when…
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1803- John Dalton Proposed the atomic theory
Skip to
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1869- Dmitri Mendeleev Arranged elements into 7 groups with
similar properties… 1st version of periodic table.
Next was
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Discovered electrons and isotopes
1897- JJ Thomson
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Famous experiment determined the charge of an electron… which is??
1909 Millikan
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Established that the nucleus of an atom was very dense and positively charged while electrons were outside the nucleus
1911 Rutherford
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Made a model of the atom where electrons were in different orbitals
1922 Niels Bohr
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Discovery of the neutron
1932 Chadwick
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First of all… Elements are substances that cannot be broken down into simpler parts
Elements are made of atoms.. .Carbon is made of carbon atoms etc.
How small is an atom??? We can break down an atom but it loses its
properties when we do…
Moving on to atomic structure
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Three types of particles Electrons Protons Neutrons
Atoms are made of…
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Very tiny Mass is basically zero (m=0) Negative charge (-1) Located flying around the nucleus
Electrons
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Very large compared to electrons (mass =1) Positive charge (+1) Located in the nucleus of an atom
Protons
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Large like protons (mass=1) Neutral charge or no charge Located in the nucleus
Neutrons
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If this were the size of hydrogen nucleus, the electron would be spinning about a quarter mile away….
In a neutral atom, protons always equal electrons
Hydrogen has… 1 proton… 1 electron Helium has… 2 protons… 2 electrons
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Atomic number = number of protons in nucleus
Atomic Mass= how many protons AND neurtons
How many protons in H? How many neutron in H How many electrons?
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How many P? N? E?
Let’s try another
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P? N? E?
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Hydrogen:
Helium:
Bohr Models
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Boron
Neon (noble gas)
More Bohr Models
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Magnesium
Last one