Download Internal Structure of Atoms - Belle Vernon Area School District

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Periodic table wikipedia, lookup

Livermorium wikipedia, lookup

Promethium wikipedia, lookup

Dubnium wikipedia, lookup

Tennessine wikipedia, lookup

Chemical element wikipedia, lookup

Extended periodic table wikipedia, lookup

History of molecular theory wikipedia, lookup

Ununennium wikipedia, lookup

Unbinilium wikipedia, lookup

Transcript
Internal Structure of
Atoms
Chapter 3-Section 2
1
Subatomic Particles
 Electrons,
protons, and neutrons
 Electricity – J.J.Thomson –
Electrons
 Metal plates – electrodes
–Cathode –Anode +
2
Cathode Ray Tube
3
Electrons
The
wheel in the cathode ray
tube-mass
Originate at negatively
charged side – negatively
charged electrons
Magnet
4
Mass
 Further
experiments found the
mass of an electron to be
5.485799 x 10-4 amu
 2000 times lighter than an atom
 The charge was found to be
-1.602189 x 10-19 C
 C = Coulombs – SI unit
5
Charges
An
atom is not the simplest
form of matter
Since electrons (e-) are
negative, how is an atom
neutral?
6
The Nucleus
Thompson’s
plum pudding
model
This is no
longer a valid
model
7
Rutherford’s Nucleus
Gold
foil experiment
–Alpha particles
–Some passed through and
some were repelled away
from the foil
8
Rutherford’s Nucleus
2
years later…
 Must be a concentrated tiny
space with a mass larger than
the α particle
The rest of the gold foil would
be empty space.
9
The modern nucleus
The
nucleus is a dense central
portion of the atom that is
positively charged.
The nucleus has most of the
mass of the atom, but is very
small compared to the entire
atom.
Marble and football
10
Protons and Neutrons
Protons
=+
-19
Charge = 1.602189 x 10
C
Mass = 1.0073 amu (2000
times the mass of an electron)
11
Protons and Neutrons
A
neutral atom has equal
numbers of protons and electrons
Masses
of all atoms (except H)
were greater than the mass of
e- and p+ combined so where
does this mass come from?
12
Neutrons
 Joliot-Curie
and Chadwick
experiment with beryllium
–Alpha particles
–Beam of power not deflected by
electric or magnetic fields
These particles must be neutral
Mass of 1.0087 amu
13
Coulomb’s Law
States
that the force between
two charged particles is
inversely proportional to the
square of the distance
between them.
14
Coulomb’s Law
Force = 0.58 N Distance = 0.020 pm
Force = 2.32 N
Distance = 0.010 pm
15
Strong Force
The
force that holds the protons
and neutrons in a nucleus.
It is greater than the repulsive
forces at close distances.
Must be neutrons in nucleus if
there is more than one proton.
16
Atomic Number
Atomic
number – the number of
protons in the nucleus of an atom
# of protons =#of electrons
Always whole numbers
Same for all atoms of the same
element.
17
Mass Number
The
total number of protons
and neutrons in the nucleus of
an atom.
#
of Neutrons=Mass# - Atomic#
Can
vary for atoms of the
same element.
18
Boron
The
atomic number of boron is 5.
The mass number of boron is 11.
The number of protons and
electrons are equal to the atomic
number.
19
Atomic
Number
Element
Symbol
Boron
Mass
Number
20
Boron
Electrons
=5
Protons = 5
Neutrons = 11 – 5 = 6
21
Copper
How
many protons, neutrons,
and electrons are present in
copper which has an atomic
number of 29 and a mass
number of 64?
22
Copper
Electrons
= 29
Protons = 29
Neutrons = 35
23
Atomic Structure
Atomic
and
mass
numbers can
be written
beside the
elements
symbol
Mass Number
9 Be
4
Atomic Number
24
Concept Check
What
three subatomic particles
are important to chemistry and
what are their electrical
charges?
25
Isotopes
Isotope
– An atom that has
the same # of protons as
other atoms of the same
element but has a diff. # of
neutrons
Many elements exist as
mixtures of isotopes.
26
Lead Isotopes
Name
# of
Mass
Amt
Neutrons (amu) (%)
Lead - 122
203.973 1.4
204
-206
124
205.974 24.1
-207
125
206.976 22.1
-208
126
207.977 52.4
27
Radioisotopes
Some
elements have only one
stable isotope and will degrade
and are called radioisotopes.
Unstable nuclear
configurations.
Unstable atoms that undergo
radioactive decay.
28
Unstable in Nature
Some
elements have no stable
isotopes.
Technetium has no stable
nucleus.
Was the first element to be
made artificially in a
laboratory.
29
Section Review
Complete
numbers 1-6 in
the section review on page
89.
30