Download Nuclear Reactions Created by Patrick Haney The atoms of each

Nuclear Reactions
Subatomic Particles
The atoms of each element behave very differently,
but they all have something very important in
common.
Every atom is made of the same subatomic particles:
Protons
Neutrons
Electrons
Subatomic Particles
Protons have a positive charge.
Neutrons have zero charge.
They neutral and not positive or negative.
Electrons have a negative charge.
Subatomic Particles
In order to understand chemistry, you have
to understand the structure of atoms.
Electrons fly around relatively free
in the Electron Cloud.
Protons and Neutrons are
joined together in the
nucleus.
Understanding the mass of atoms:
When discussing subatomic particles, scientists
often talk about their relative masses. This just
means how their masses compare to one
another.
Protons
Relative
Mass
1
Neutrons
Electrons
1
1
1840
Understanding the mass of atoms:
Because electrons are 1/1840th the size of
protons and neutrons, they are too small to
concern ourselves with when we are
discussing mass.
Electrons
1
1840
What is the identity of each of the
elements below?
Hydrogen
Lithium
Helium
Elements are identified by the number of protons in the
nuclei of the atoms that make up the element. Atoms of
the same element can have different numbers of
neutrons. Atoms of the same element with different
numbers of neutrons are called isotopes.
Atoms get their MASS NUMBERS from
their relative mass.
Hydrogen-2
Lithium-7
Helium-4
The MASS NUMBER is the total number of
protons and neutrons in the nucleus. We
identify different isotopes by noting their mass
numbers.
Mass numbers do NOT tell us the number of
neutrons in an isotope. To find the number of
neutrons in an isotope, you must take the
mass number and subtract the atomic number
# of neutrons = mass number – atomic number
How many neutrons are
in the nucleus of a
helium-5 atom?
Helium-5
5 – 2 = 3 neutrons
Knowing the number of
protons and neutrons allows
you to identify an isotope.
Identify the Isotope with this combination of
protons and neutrons.
Beryllium - 9
4 protons and 5 neutrons = ____________
Which element would have 4
protons? Beryllium
What would the mass number be?
4+5=9
Determine how many neutrons
are in each of the isotopes listed
on your notes.
&
Write the names of the isotopes,
including their mass numbers,
on your notes.
Understanding Isotopes
As we discuss nuclear chemistry, we will be
using a special notation for specific isotopes.
As usual, we will use an elements
symbol to abbreviate the element.
To identify the specific isotope, we
will place the mass number in the
top left corner next to the symbol.
It will be necessary to know the
atomic number as well. This is
placed on the bottom left.
13
6
C
Understanding Isotopes
Most of the time, the atomic numbers will
not be written for you before you begin.
These will have to the added by you.
What atomic numbers should be added to
the chemical symbols below.
13
6
C U N
235
14
92
7
Add the correct atomic
numbers to each of the
isotopes on your notes.
Unstable Isotopes
There are several different isotopes for any
given element. Some of these isotopes will
be stable, while other will be unstable.
12
6
C
Stable
13
6
C
Stable
14
6
C
Unstable
Unstable isotopes eventually undergo the
process of nuclear decay. This means that the
atoms break apart releasing energy and particles.
Types of Nuclear Decay
The largest particle that is emitted from a
nucleus during nuclear decay is known as an
alpha (α) particle.
Alpha particles are composed of
2 protons and 2 neutrons.
These means that they have a
mass number of 4
and
an
atomic
number
of
2.
4
Because it has 2 protons and 2
neutrons, this is essentially
2
the nucleus of a helium atom.
He
Types of Nuclear Decay
Very tiny negatively charged particles can also be
emitted during nuclear decay. These are known as
beta (β) particles.
Beta particles are essentially electrons that are
emitted from the nucleus of an atom.
Remember, electrons do not have
enough mass to consider, so we place
a 0 in the mass number spot.
0
They have a -1 charge, so we place this
in the atomic number spot.
-1
e
Because beta particles are essentially
electrons, we use the letter e as a symbol.
Beta Decay
When a nucleus undergoes beta decay, an electron
is emitted from a neutron. When the negative
charge leaves the neutron, the neutron becomes a
proton! This causes the mass to remain constant,
but the atomic number increases by one.
14
6
7
N
C
Nitrogen-14
Carbon-14
Types of Nuclear Decay
Another very tiny particle that can be emitted
during nuclear decay is known as a
positron.
Positrons are very similar to electrons in size,
but they have a +1 charge.
Just like electrons , positrons do not
have enough mass to consider, so we
0
place a 0 in the mass number spot.
+1
e
They have a +1 charge, so we place
this in the atomic number spot.
Because positrons are the antiparticles of
electrons, we still use the letter e as a symbol.
Unstable Isotopes
When a nucleus undergoes a positron emission, a
positron is emitted from a proton. When the positive
charge leaves the proton, the proton becomes a
neutron. This causes the mass to remain constant,
but the atomic number decreases by one.
11
6
5
B
C
Carbon-11
Boron-11
Gamma (γ) radiation
Whenever a nuclear reaction occurs, there is a large
amount of energy released. This energy includes all
types of radiation including the highest energy
radiation known as gamma (γ) rays.
0
0
γ
Gamma rays are energy and not
matter, but they could appear in a
nuclear reaction equation.
They have no mass, so we a 0 in the
mass number spot.
They have no charge, so we a 0 in
the atomic number spot.
Types of Nuclear Decay
Neutrons are also often involved in nuclear
reactions. They can be shot into a nucleus to
trigger a nuclear reaction or emitted from the
nucleus after a nuclear reaction.
1
0
n
Just like protons, neutrons have a
mass of 1.
They have no charge, so we a 0 in
the atomic number spot.
We use a lowercase n as the symbol
for a neutron. This is to keep it
from being confused with nitrogen.
Balancing Nuclear Reactions
Nuclear reactions are very easy to balance.
Once again, we think of the arrow as our
equal sign. Then, we follow a few easy steps.
239
94
Pu  2
4He
+
Step 1: Add atomic numbers to the elements
if they are not already there.
Balancing Nuclear Reactions
Nuclear reactions are very easy to balance.
Once again, we think of the arrow as our
equal sign. Then, we follow a few easy steps.
239
94
Pu  2
4He
+
235
92
Step 2: Use simple algebra to determine the
mass number and atomic number of the
unknown element.
Balancing Nuclear Reactions
Nuclear reactions are very easy to balance.
Once again, we think of the arrow as our
equal sign. Then, we follow a few easy steps.
239
94
Pu  2
4He
+
235
92
U
Step 3: Use the atomic number to determine
which element’s symbol should be placed in
the blank.
Complete the nuclear
reaction problems on
your notes.
Types of Nuclear Reactions
There are 2 main types of nuclear reactions you need
to be familiar with: fission and fusion.
Fission reactions occur
when a nucleus breaks
apart into several
smaller nuclei. The first
atom bombs were the
result of a fission
reaction.
Types of Nuclear Reactions
There are 2 main types of nuclear reactions you need
to be familiar with: fission and fusion.
Fusion reactions
occur when a
nuclei join together
into one larger
nucleus. Fusion
reactions are what
occur in the sun
and other stars.
Image from Wikipedia
The high energy radiation
released during nuclear
reactions can lead to radiation
poisoning which can cause
serious illnesses and
commonly leads to death.
Because of this, radioactive
substances must be treated
with great care.
Radioactive
Substance
Guided Notes