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Basics Of Chemistry

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Basics Of Chemistry 8th Science 2012 Matter Defined Matter anything that has volume or mass. Everything you see and don t see. Definitions Element- pure ... – PowerPoint PPT presentation

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Title: Basics Of Chemistry


1
Basics Of Chemistry
  • 8th Science 2012

2
Matter Defined
  • Matter anything that has volume or mass.
  • Everything you see and dont see.

3
Definitions
  • Element- pure substance that cannot be separated
    into simpler substances by physical or chemical
    means.
  • Represented by a symbol Au stands for what?

4
Definitions
  • Atom Smallest particle into which an element
    can be divided and still be the same substance,
    retaining its properties

5
Evolution of the Atomic Theory
  • Democritis 440 BC
  • Greek philosopher who said that if you cut a
    substance in half again and again and again
    eventually you would have an uncuttable piece
  • said that all atoms made of a single material
    formed into different shapes and they join
    together to make different materials
  • Greek word atomos, which means indivisible

6
John Dalton - 1803
  • Studied the atmosphere and other gases and
    developed atomic theory.
  • Dalton demonstrated that elements combine in
    specific proportions to make different substances

7
John Daltons Atomic Theory
  • 1. All substances are made of atoms.
  • 2. Atoms are small particles that cannot be
    created, divided, or destroyed.

Daltons New System of Chemical Philosophy
8
Daltons Atomic Theory, continued
  • 3. Atoms of the same element are identical in
    size, mass and other properties.
  • 4. Atoms of different elements combine to make
    chemical compounds.
  • 5. In chemical reactions, atoms are combined,
    separated, or rearranged.

9
J.J. Thomson - 1897
  • discovered that there are small particles inside
    the atom, so the atom can be divided into smaller
    parts

10
JJ Thomson, continued
  • Experimented, using a cathode-ray tube to
    discover negative particles he called corpuscles
  • these negatively charged particles found in all
    atoms are now called electrons

11
Thomsons Model
  • Plum Pudding model
  • Described electrons as scattered all about the
    atom

12
Ernest Rutherford - 1908
13
Rutherford, continued
  • Discovered a tiny, extremely dense, positively
    charged region called a nucleus
  • Most of the atoms mass was in the nucleus and
    electrons traveled around the nucleus

14
Rutherford contd
  • said the atom was mostly empty space

15
Niels Bohr 1913
  • said the electrons travel around the nucleus in
    definite paths

16
Erwin Schrödinger and Werner Heisenberg - 1926
  • Said electrons travel in clouds, not definite
    paths but we still use the Bohr Model to
    represent atoms.

17
The Atom
18
Subatomic Particles
  • Protons
  • Determine the identity of the matter
  • positively charged particles
  • found in the nucleus
  • Mass 1.67262158 10-27 kilograms
  • 0.000000000000000000000000017 kg
  • Each proton is 1 amu
  • AMU stands for Atomic Mass Unit

19
Subatomic Particles
  • Neutrons
  • Neutrons are the glue that holds the protons
    together in the nucleus
  • no charge
  • found in the nucleus
  • mass is 1 amu

20
Subatomic Particles
  • Electrons
  • Determine the reactivity
  • Negatively charged
  • Found around the nucleus within electron clouds
  • Mass is very small, almost zero

21
Atoms are NEUTRAL
  • Atoms are neutral because the number of protons
    equals the number of electrons.

22
How To Read a Square
  • 8
  • O
  • Oxygen
  • 15.9994
  • Elements are identified by their atomic number
    the number of protons. Also equals the number of
    electrons.
  • Chemical Symbol
  • Element Name
  • Atomic Mass

23
PEN Method
  • SLIDE, SLIDE, ROUND THE BOTTOM SUBTRACT TOP
  • P 8
  • E 8
  • N 8
  • 8
  • O
  • Oxygen
  • 15.9994
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