Download atomic theory student ch 4-10

CHEMISTRY - CHAPTER 4 AND 10 - ATOMIC THEORY
I.
IT
Introduction : early theories on what matter is made up
of.
A.
400 B.C. - Democritus.
1.
_______________________
2.
things were made up of indivisible particles
which he called atoms - _________________
_______________________________________
3.
rough atoms - ______________________
smooth atoms - _____________________
4.
atoms of everything existed.
5.
since atoms of everything exist, this does
not allow for chemical reactions.
B.
Aristotle = 384 - 322 B.C.
1.
______________________________
a.
4 elements = ____________________
1.
these were really all the same
thing called _____________
2.
THIS THEORY WAS VERY MUCH ACCEPTED BECAUSE
WAS NOT AS ABSTRACT AS DEMOCRITUS' WAS!
3.
also does not allow for chemical reactions.
C.
II.
late 1700s = Lavoisier and Priestly.
1.
dealt with air and water.
2.
separated air into ___________________
3.
separated water into _________________.
4.
Lavoisier.
a.
conducted a reaction in a closed system.
b.
proved that ________________________
__________________________________
c.
made up of indivisible particles - this led to the ______________________
_________________________.
D.
Proust.
1.
dealt with fool's gold.
2.
broke down into ______________________.
3.
broke water down into hydrogen and oxygen.
4.
his work led to the _________________
_____________________________
a.
__________________________________
______________________________________
Dalton's Atomic Theory - 1803.
A.
beginning of modern chemistry.
B.
his theory - back to Democritus' theory.
1.
2.
3.
4.
5.
C.
This theory allows for chemical reactions, which
leads to a lot of progress in chemistry.
III.
Dalton's Law of Multiple Proportions.
A.
He predicted this law.
B.
C.
Dalton's atomic theory was the first scientific
model:_______________________________
1.
2.
3.
IV.
V.
VI.
Gay-Lussac.
A.
Discovered that volumes of reacting gasses and
their products ____________________________
________________________________________
B.
example.
2 H2 (g) + O2(g) ----> 2 H2O (g)
C.
example.
N 2 + 3H2 ---> 2NH3
________________________________________
Avogadro.
A.
equal volumes of gases (at same temp, pressure)
have _____________________________________
1.
this discovery led to the discovery of the
gas laws.
2.
one mole of any gas at 0 C and 1 atmosphere
of pressure is ___________________
(now we can use this in stoichiometry
problems!)
a.
1 atmosphere
Atomic Particles.
A.
Electrons.
1.
discovered in a cathode ray tube :
vacuum with oppositely charged ends.
2.
_______________ - discovered them in 1897.
a.
determined the charge/mass ratio of this
particle.
3.
_______________ - oil drop experiment to
determine the actual charge of the electron.
a.
e- = ___________________________
b.
we say that the e- has 1 unit of
electric charge.
4.
mass of e- = 1/1837 of H atom.
= 1/1836 of a proton.
= ____________amu
=_____________grams
B.
Protons.
1.
discovered by _____________ when he used a
modified cathode ray tube.
a.
found that there were rays travelling in
the opposite direction from the
electrons.
2.
found that the charge on these particles was
positive and equal in size to the electron.
3.
the proton has 1 unit of positive charge.
4.
mass = 1837 times that of an electron.
5.
mass of proton is 1 amu
C.
VII.
Neutron.
1.
discovered by _______________________
2.
essentially same mass as proton. ( 1 amu)
3.
no charge.
Atomic Mass and Atomic Number.
A.
Atomic Mass.
1.
almost all of the mass of an atom is located
in the nucleus.
2.
atomic masses measured in a.m.u.
a.
1 amu = 1/12 mass of C 12 atom.
(6 n, 6 p+, 6 e-)
b.
a C 12 atom has a mass of exactly 12
amu, the standard for amu.
3.
usually chemists deal in moles - use
Avogadro's number to convert amu to grams.
( ________________________)
B.
Atomic Number.
1.
the number of protons in an element is
called the atomic number of the element (Z).
2.
the number of protons determines what element
it is.
3.
number of e- = number of p+ in a neutral
atom.
4.
number of neutrons _____________________
5.
for this reason, the masses of all of the
atoms in an element are not the same.
6.
the reported atomic mass of an element is the
_______________________________________
7.
8.
9.
the protons and neutrons are called _________
because they're in the nucleus.
mass number = number of nucleons (A).
number of neutrons = _________________
Example: In Silicon atoms:
92.21% have a mass of 27.97 amu
4.70% have a mass of 28.976 amu
3.09% have a mass of 29.974 amu.
What is the average atomic mass of Silicon?
Example: In the Francium atom with mass
number 220, how many protons, neutrons, and
electrons are there?