1 Slide 2 2 2 I could have swore there was a mouse here a moment
ago. Slide 3 3 3 Atoms and Elements CHAPTER 2 Slide 4 4 4 Early day
scientists - Greeks were the first to try and explain chemical
changes. Believed that all matter consisted of four basic things.
(fire, air, water and earth) Slide 5 5 5 Democritus Greek, 460-370
B.C. Created the word atomus (atom) Believed everything was
composed of atoms Proposed that the world is made up of empty space
and atoms. He believed everything was composed of this and the atom
was indivisible. Slide 6 6 6 Alchemy - A pseudo science, purpose of
the science was to attempt to make gold. Such elements as Hg, S,
and Sb were discovered due to this science. Slide 7 7 7 John Dalton
(1766- 1844) - English - first to prepare a table of relative
atomic weights and the Law of multiple proportions. Daltons early
day symbols Slide 8 8 8 Law of multiple Proportions - when two
elements form a series of compounds, the ratios of the masses of
the second element that combine with 1 gram of the first element
can always be reduced to small whole numbers. Ex: NO and NO 2 Slide
9 9 9 9 2 2.1 Slide 10 10 10 Dalton's Atomic Theory - 1. Each
element is made up of tiny particles called atoms. 2. The atoms of
a given element are identical; the atoms of different elements are
different in some fundamental way or ways. 3. Chemical compounds
are formed when atoms combine with each other. A given compound
always has the same relative numbers and types of atoms. 4.
Chemical reactions involve reorganization of the atoms -- changes
in the way they are bound together. The atoms themselves are not
changed in a chemical reaction. Slide 11 11 11 J.J. Thomson
English, (1856 - 1953) In 1897 discovered the particle the
electron. Discovered it by using a cathode ray. Slide 12 12 12 What
charge does an electron have? Negative Slide 13 13 13 Cathode Ray
Tube A stream of electrons is produced at the negative pole of an
applied electric field. The electron was isolated using this
device. Slide 14 14 14 J.J. Thomson, measured mass/charge of e -
(1906 Nobel Prize in Physics) 2.2 Slide 15 15 15 George J. Stoney
Irish, 1826-1911 In 1891, he proposed the term 'electron' to
describe the fundamental unit of electrical charge, and his
contributions to research in this area laid the foundations for the
eventual discovery of the particle by J.J. Thomson in
1897.electronJ.J. Thomson Dont take down Slide 16 16 16 The modern
view of the atom was developed by Ernest Rutherford of New Zealand
(1871-1937). Slide 17 17 17 1. 1.atoms positive charge is
concentrated in the nucleus 2. 2.proton (p) has opposite (+) charge
of electron 3. 3.mass of p is 1840 x mass of e - (1.67 x 10 -24 g)
particle velocity ~ 1.4 x 10 7 m/s (~5% speed of light) (1908 Nobel
Prize in Chemistry) 2.2 Slide 18 18 18 Ernest Rutherford Canterbury
University in Christchurch, NZ Rutherford laboratory Slide 19 19 19
Rutherford Slide 20 20 20 Ernest Rutherford New Zealand, ( 1871 -
1937) Named the alpha and beta particles and the gamma ray. Named
the proton and is known for the use of the foil method to detect
the proton. Conducted the gold foil experiment, which led to the
discovery of the nucleus Slide 21 21 21 James Chadwick English,
(1891-1974) Isolated the neutron in 1932. Slide 22 22 22 A TOMS AND
E LEMENTS Slide 23 23 23 ATOM COMPOSITION protons and neutrons in
the nucleus.protons and neutrons in the nucleus. the number of
electrons is equal to the number of protons.the number of electrons
is equal to the number of protons. electrons in space around the
nucleus.electrons in space around the nucleus. extremely small. One
teaspoon of water has 3 times as many atoms as the Atlantic Ocean
has teaspoons of water.extremely small. One teaspoon of water has 3
times as many atoms as the Atlantic Ocean has teaspoons of water.
The atom is mostly empty space Slide 24
