» What is the
name of this
device?
» Which
scientist
used this
device?
»Cathode
Ray tube
»JJ Thomson
»What experiment did
Millikan do and what
was one of his
conclusions?
Oil Drop Experiment
Determined the mass of an electron (1/2000th the
mass of H atom)
Determined the charge on the electron (negative)
»What experiment did
Rutherford do and
describe it?
» Rutherford did the gold foil
experiment
» Bombarded a thin piece of gold foil
with fast moving positively charged
alpha particles
» Expected the alpha particles to pass
straight through. Most did, but 1 in
8000 were deflected back.
»Complete the table for
the main subatomic
particles.
Particle
Relative
Charge
Mass
Number
Location in
atom
Proton
Neutron
Electron
+1
0
-1
1
1
0
nucleus
nucleus
Outside
nucleus
»State 3 observations
that Rutherford made
(what did he see) and 3
conclusions he made
from those observations.
1.Most of the alpha particles passed
straight through the foil – atom is
mostly empty space
2.1 in 8000 particles bounced back –
atom has a very tiny, dense nucleus
3.Some alpha particles deflected –
nucleus has a positive charge b/c
positive alpha particles are repelled
»What does the atomic
number represent?
»The number of protons
in the nucleus of each
atom of that element
»What does the mass
number represent?
»The number of protons
+ neutrons in the
nucleus
»Define isotope
»Atoms of the same
element that have
different masses
»How do nuclides of the
same element differ
from each other (be
specific)?
»The have a different
number of neutrons
»Write the nuclear
symbol and hyphen
notation for the nuclide
that has 2 protons and 2
neutrons.
4
»Helium-4
He
2
»Define atom
»The smallest particle of
an element that retains
the chemical properties
of that element
»What nuclide is used as
the standard in the
relative scale for atomic
masses?
»What is its assigned
atomic mass?
Carbon-12
12 amu
»What is the definition
of the mole?
The amount of particles equal to the
number of atoms in exactly 12 g of
Carbon-12
»How many particles
are in one mole?
23
6.022x10
»What is the name
given to the number of
particles in one mole?
Avogadro’s number
»Calculate the average atomic
mass of argon to 2 decimal
places give the following
isotopes:
»Argon-36 (35.97amu; 0.337%)
»Argon-38 (37.96amu; 0.063%)
»Argon-40 (39.96amu; 99.600%)
39.95 amu
»Naturally occurring boron is
80.20% boron-11 (11.01amu)
and 19.80% of another
isotope. The average atomic
mass of boron is 10.81amu.
What must the atomic mass
of the second isotope be?
10.01 amu
»How many atoms are
in 6.755 mol Pb?
4.068x1024 atoms
»How many atoms are
in 0.250 mol Si?
1.51x1023 atoms
»What is the mass in
23
grams of 3.011x10
atoms F?
9.499 g
»What is the mass in
grams of 25 atoms W?
7.6x10-21 g
»Determine the number
of atoms in 1.50g K.
2.31x1022 atoms
»Determine the number
of atoms in 0.02550 g Pt.
7.872x1019 atoms
»Write the nuclear
symbol and hyphen
notation for the nuclide
that has 6 protons and 8
neutrons.
14
»Carbon-14 6 C
»How many isotopes
does hydrogen have?
Describe them.
»Protium – 1 proton, 0 neutrons, 1
electron (most common)
»Deuterium – 1 proton, 1 neutron,
1 electron
»Tritium – 1 proton, 2 neutrons, 2
electron (radioactive)
»What forces holds the
nuclear particles
together in the
nucleus?
»Nuclear forces
»How did Dalton’s theory explain
the law of conservation of mass?
»Chemical reactions involve the
rearrangement of atoms, but
atoms are not subdivided,
created or destroyed.
»How many protons,
electrons, and neutrons
are there in an atom of
chlorine-37?
+
0
»17p ; 17e ; 20n
»How many protons,
electrons, and neutrons
are there in an atom of
bromine-80?
+
0
»35p ; 35e ; 45n
»Write the hyphen
notation for the element
that contains 15 electrons
and 15 neutrons.
»Phosphorous-30
»What is an amu?
»1/12 the mass of a
carbon-12 atom
»Atomic mass unit
»What is the mass in
grams of 3.50 mol of
the element copper?
»222 g of Cu
»The atomic mass of
Tungsten is 83.84amu.
What is the molar
mass of Tungsten?
»83.84 g/mol
»How many atoms are
in 132.90543g of
Cesium?
23
»6.022x10 atoms of Cs
»How many moles of
calcium are in 5.00g of
calcium?
»0.125 mol Ca
»How many atoms of
lead are in 52.7g of
lead?
23
»1.53x10 atoms of Pb
»How many neutrons
does uranium 238
have?
»146 neutrons
»How many protons
does osmium-190
have?
»76
»What is the name of
the nuclide that has 22
protons and 25
neutrons?
»Titanium-47
»Write the nuclear
symbol for the isotope
of sodium with mass
23
23Na
11
»A student finds that 15.20g of
nitrogen will react with
17.37g, 34.74g, or 43.43g of
oxygen to form three
different compounds. This is
an example of which law?
Law of Multiple Proportions
»State the 5 points of
Dalton’s atomic theory
1. All matter is composed of atoms
2. Atoms of a given element are identical in size, mass, and other
properties
3. Atoms cannot be subdivided, created, or destroyed
4. Atoms of different elements combine in simple whole-number
ratios to form chemical compounds
5. In chemical reactions, atoms are combined, separated, or
rearranged.
»Which aspects of
Dalton’s atomic theory
were incorrect?
Atoms cannot be subdivided – we know atoms are
made of protons, neutrons & electrons.
Atoms of a given element are identical in size, mass…
- we know isotopes exist
»Describe 4 properties
of electrons that were
determined based on
the experiments of
Thomson and Millikan.
1.Electron is negatively charged
th
2.Has a mass of 1/2000 of H
atom
3.Has a fixed charge to mass ratio
4.Present in atoms of all elements