Download NotesHistory of Atomic Structure

GPS: 3a, 3f
Date: _____/_____/_____
The History of Atomic Structure
Part I: The Road to Modern Atomic Theory
 Early ________ - _____ B.C.
 common ______ theory was that all ______ consisted of
four "________"—______, _____, _____, and ______.
 _________ (460-360 BC) = a philosopher who _________
that all matter was made of __________ particles (______). Democritus
 his theory was based on _______ _________, not _____.
 philosophers/scientists of this time period did not think doing ___________
was necessary—you could reach the _____ by ____ _______ _________.
 _________ (the process of _______ base _______ to ____) was the main
form of _______________ from this time period until the ____ _____'s.
 Modern Era Theories/Laws—_____’s – early _____’s
 Robert _____, in the mid-1600’s, defined “_______” as a
_________ that _____ be ______ ____ into ______ substances.
 Antoine _______ – mid 1700’s – considered to be the _______
Boyle
of _______ _________.
 used the _________ ________ and did careful, _________
____________ involving the __________ of ______.
 is credited with developing _________ in 1777 for the…
 law of ___________ of ____: mass is neither ________ nor
__________ in an average _____. _____. (this means ______,
Lavoisier
_______, etc.  __________ matter)
 Joseph ______—published Law of _______ __________ in 1794:
 a chemical _______ contains the same elements in _______
the same ___________ (by _____) regardless of the ____ or
_______ of the sample. (this means water = H2O ________
Proust
you get it, _________ much you have)
 law of ________ proportions: picture two ________ compounds with the
_____ two elements in them—i.e. ______ ________, _____ _______—these
compounds will have the same _____, _____ ______ _____ in their required
_______ as they do in their chemical ________.
carbon monoxide = ___
carbon dioxide = ___
Ex:
C
O
C = 12g O = 16g
O
C
O
C = 12g O = __ g
CO = __ oxygen,
CO2 = __ oxygens,
__:__ ratio in oxygen _____
CO = ___ g of oxygen,
CO2 = ___ g of oxygen,
__:__ ratio in oxygen _____
Part II: _____ Atomic Models
 Dalton, John—“_____ _______” model
 English ____________ (____), proposed ____________ for the 3 _____ above
 thought elements were composed of ______, which were ____________
 Dalton’s _______ _______: (five parts)
1. all _______ is composed of very ____
particles called ______
2. atoms of a given _______ are _______
in ____/_____/other properties; other
elements’ atoms are _________
3. atoms cannot be __________, _______,
or __________
Dalton
4. in chem rxtn, atoms are ________/________/_________
5. atoms of diff. _______ combine in small, _____-__ratios to form compounds
 “_____ ___” model of the atom. Even after _____ years of the atomic _______,
the ________ of the atom was still _________.
 at this point, the _____ was still thought to be the ________ unit of matter.
 Thomson, Joseph John—“____ ________” model (or “______ _____”)
 English ________ (_____), performed ________-____ tube experiments
 discovered the _________ and its _______
 cathode-ray tube: glass _______ tube (attached to a _______
source) through which ________ flows, producing a _____.
 _______ travel towards ______ (________ charges attract)
 _______ ______ placement shows that particles were
________, had _____, and had a ________ charge
Thomson
 this model shows the electrons on the ________ of the
_______-charged atom (if there were ________ parts to
atoms, then there must be ________ parts as well to
________ it, because most matter is ________).
 cathode rays were not like _______ light—they could be
________ by ________ or ________ fields, and they could
pass through thin metal _____, since they were so _____.
 Millikan, Robert A.—see ________ model
 American ________ (_____), performed experiments that
determined the ____ of _______ to be about 1/_____ the
_____ of the ________ atom, or about ______ x 10___ kg.
 because atoms are ________ ______, they must contain
some __ charge to ______ all the __ charges from the ___.
Millikan
 because e- have so much _____ mass than the _____ atom
itself, there must be other, much _______ particles make up most of the ____.
 Rutherford, Ernest—“_______ ____, _______ ______” model
 ____ _______, along with Hans ________ and Earnest





________ (____) performed the ___-___
experiment, leading to the discovery of
the ________-_______ _______.
experiment = ________ a thin gold ____
Geiger
Marsden
with ______-particles (____).
Rutherford
they did this assuming that the _______ and ____ within each
atom was ________ __________ throughout the atom, and expected the alpha
particles to go _____ ________.
 most did, but some (1/_____) actually
______ ____ toward the _______ source!
 Rutherford ___________ that the reason
some particles bounced back was that
there was a very ______ ________________area that occupied only a very
_____ amount of _____ within the core of
the atom (________).
to explain this, Rutherford proposed a new _____ for the
atom. He imagined the atom as a ________ _____ ______
with a nucleus as the ___ and electrons orbiting like _____.
although the nucleus was only ___ ______ ________ the
_______ of the atom, it had over _____% of the _____.
Rutherford: "It was as though you had fired a _______-____
_____ at a piece of ______ _____ and it had _______ ____ and ____ ___."
 Bohr, Neils—“________ _______ _____” model
 Danish ________ (____), new model that explained why
_______ electrons do ___ fall in towards the _______ _______.
 Bohr used _________'s ideas to explain the ________ of the
________ atom with one electron—_________.
 he suggested that an electron was ________ to certain
allowed ________ around the ________.
Bohr
 if it ______ from one orbit to another, the atom _______
or ________ light.
 thus, electrons only _____ in specific ______ _____ (orbits
around the nucleus) similar to the _____ of a _______.
 these levels reflect ________ ________ of ________ that
are _______ to move _______ from one _____ to another.
 unfortunately, this model only works for 1 atom—_______.
 Chadwick, James—“__ ________ ______ _______” model.
 discovered the ________ in the nucleus
 he used work previously done by _________
to establish the _________ of the _______:
 using __ _____ to bombard __, he found
_____ of __ which had been ______ ___.
 in _____ he speculated that hydrogen
_____ were a _______ _____ of all nuclei.
Chadwick
He suggested the name ______ for this unit.
 other _______ for the proton came from the ________ ________ and ______ of
nuclei which ______ by ______ units from element to element.
 these new _______ particles in the nucleus were found to be quite ______
(about _____ times the mass of the ___).
 However, the ____ mass of most atoms did not ___ __ to ____ the ______ of
just the _______ and _______ together. Therefore, there must be ________,
__-______ particle in the atom that adds the __________ weight.
 around _____, ____ ______-____) (________ of ______ and
_____ _____) performed an experiment in which _______ was
_________ with alpha-particles, and a ____ of particles with
high ___________ _____ emerged.
 she was conducting many ________ experiments during this
Joliot-Curie
time. However, she was ____ searching for ________.
 ________ realized that some of her experiments might be used to ____ the
elusive ______, so he ________ her experiments with this _____ in mind.
 he was able to determine that these ________ had approximately the _____
___ as a ______. When they were exposed to _______ and ________ _____,
and they were not ________, he determined that they had __ _______, either.
 he called these ___-____, __________ particles “_________.”
Modern Atomic Model
 e- in the modern model are arranged in “________,” not _____ (____ model).
 Orbitals are _____-like ______ around the ______ of the atom in which __ or
__ _______ are most likely to be found. They are arranged about the nucleus
on the __, __, and __ ____, which we will discuss in further detail tomorrow.