Atom_isotopes_radioisotopes

SFT1023: (INTRODUCTION TO RADIATION
AND NUCLEAR PHYSICS)

©Jabatan Fizik

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Objectives of the Course

• To provide useful information about
radiation

• To introduce basic concepts of
radiation and radioactivity

• Improve understanding of radiation –
what it is and how it interacts

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Assessment

Continuous Assessment Percentage

Test 5

Practical Report 20

Assignment (Individual) 15

Presentation 20

FINAL 40

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Lecture 1:Introduction to Radiation

Content:

• Introduction
• Atoms: Where all matter begins
• Isotopes
• Radioisotopes

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

How is Heat Transferred? Revision
Heat can travel from one place to another in several ways. The different modes of heat transfer
include:
• Conduction
• Convection
• Radiation
Meanwhile, if the temperature difference exists between the two systems, heat will find a way
to transfer from the higher to the lower system.

Conduction is defined as
The process of transmission of energy from one particle of the medium to
another with the particles being in direct contact with each other.

What is Convection?
Convection is the process of heat transfer by the
bulk movement of molecules within fluids such as
gases and liquids

Radiation is energy that moves from one place to
another in a form that can be described as waves or
particles.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

What is radiation?

• In physics, radiation is the emission or transmission
of energy in the form of waves or particles through
space or through a material medium

• When people hear the word radiation, they often think of
atomic energy, nuclear power, and radioactivity, but
radiation has many other forms.

• Sound and visible light are familiar forms of radiation;
other types include ultraviolet radiation (that produces a
suntan), infrared radiation (a form of heat energy), and
radio and television signals.

Radiation is often categorized as either ionizing or non-
ionizing depending on the energy of the radiated particles.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

What are the misconceptions about radiation?

• Many people are not aware that we are
interacting with radiation in various forms
every day of our lives.

• In fact, without radiation, we would not be
able to detect fires in our homes, see injuries
to our bones and bodies, use electronics
such as cell phones, or even see the world
around us!

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

The electromagnetic spectrum

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Examples:

• Electromagnetic radiation, such as radio waves,
microwaves, infrared, visible light, ultraviolet, x-rays, and
gamma radiation (γ)

• Particle radiation, such as alpha radiation (α), beta
radiation (β), proton radiation and neutron radiation
(particles of non-zero rest energy)

• Acoustic radiation, such as ultrasound, sound, and
seismic waves (dependent on a physical transmission
medium)

• Gravitational radiation, that takes the form of gravitational
waves, or ripples in the curvature of spacetime

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atoms: Where all matter begins

• A nucleus (protons and neutrons) that Atoms form the basic building blocks of
are kept together by nuclear forces. all matter. In other words, all matter in
the world begins with atoms – they are
• The nucleus carries a positive charge; elements like oxygen, hydrogen, and
Why?? carbon.

• protons are positively charged, and • Electrons that are in orbit around the
neutrons do not carry a charge. nucleus.

• The electrons, which carry a negative
charge, move around the nucleus in
clouds (or shells).

• The negative electrons are attracted to
the positive nucleus because of the
electrical force. This is how the atom
stays together.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Subatomic particles

• The three basic subatomic particles are

the proton, neutron, and electron.

• Protons and electrons are charged

particles.

• Neutrons are neutral or uncharged.
• Protons have a positive (+) charge, and

electrons have a negative (-) charge.

• Overall, atoms have no charge because

the number of protons is equal to the
number of electrons.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Structure of an Atom
• A unit called the atomic mass unit, or amu,

is used when discussing atoms.

• An amu is one-twelfth the mass of a carbon

atom.

• A proton and neutron each weigh 1 amu.
• The mass of an electron is about 2000 times less

than that of a proton or neutron.

Subatomic Symbol Electrical Relative mass Location in atom
particle charge
e- 0.0005(1/20000 Outside nucleus
Electron p or p+ 1- 1 Nucleus
n or n0 1 Nucleus
Proton 1+

Neutron 0

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Structure of an Atom

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atomic Symbol

"!X It describes the sub-atomic particles in the
nucleus)

X = Atomic Symbol
Z = Atomic number = number of protons
A = Mass number =proton + neutron

Location: (nucleus)

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atomic Number, Z and Mass Number, A

All atoms of the same element always have the
same number of protons.

• Atomic Number, Z
• The number of protons in an atom of any

element can be determined from the
periodic table.

• The atomic number indicates the number

of protons present.

• Z= atomic number = no of protons

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atomic Number, Z and Mass Number, A

• The number of protons gives an atom its

unique properties.

• A carbon atom, atomic number 6, contains

six protons.

• Z=6
• All atoms of carbon have six protons.
• Because atoms are neutral (no charge), the

number of electrons in an atom is equal to
the number of protons.

• Carbon must contain six electrons.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atomic Number, Z and Mass Number, A

Mass Number, A "!X
Example A= 6

• The number of neutrons in an atom can be

found from an atom’s mass number,
which is the # of protons plus the # of
neutrons.

A= p + n

Once the atomic number and the mass
number are known, you can determine the
number of subatomic particles present.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Atomic Number, Z and Mass Number, A(Example)

Atomic symbol X = C
C is carbon
So this is nucleus carbon

How many protons? Z = 6 protons
So carbon has 6 protons
How many neutrons? A = n + p
12 = n + 6 n = 6

If it is an atom, the number of electrons is
6, because an atom is always neutral

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Isotopes and Radioisotopes

Atoms of the same element can have different
numbers of neutrons.

##H $#H %#H

Z=1 Z= 1 Z=1
p=1 p=1 p=1

A = 1, 1 = n + 1 A = 2, 2 = n + 1 A = 3, 3 = n + 1
n=0 n=1 n=2

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Isotopes and Radioisotopes

p=1 p=1 p=1
n=0 n=1 n=2

Atoms of the same element can have different numbers of
neutrons.

Atoms of the same element with different mass numbers,

(no of neutrons) are called isotopes.

Isotopes can be indicated in two ways:
• Symbolic notation
• Stating the mass number after the element name:
carbon-12

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Isotopes and Radioisotopes

p=1 p=1 p=1
n=0 n=1 n=2

deuterium tritium

• Hydrogen and its two naturally occurring
isotopes, deuterium and tritium.

• All three have the same number of protons (p =
1) (labeled p or p+) but different numbers of
neutrons (labeled n).

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Isotopes and Radioisotopes

Isotopes are members of a family of an element that all have the same number of
protons but different numbers of neutrons.

For example, carbon has six protons and is atomic number 6
• Carbon occurs naturally in three isotopes: carbon 12, which has 6 neutrons

(plus 6 protons equals 12), carbon 13, which has 7 neutrons, and carbon 14,
which has 8 neutrons. Every element has its own number of isotopes.
• Chemically, all three are indistinguishable, because the number of electrons in
each of these three isotopes is the same.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Isotopes and Radioisotopes

• Most naturally occurring isotopes have a stable nucleus.
• Isotopes that are not stable become stable by spontaneously emitting

radiation from their nuclei. This is radioactive decay.

• Isotopes that emit radiation (not stable) are also called radioisotopes.
• All the isotopes of elements with atomic number 83 and higher are

radioactive.

• Some smaller elements also have radioisotopes.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

Radioisotopes
• Some isotopes - such as carbon-12 - will happily continue to exist as

carbon unless something extraordinary happens.
• Others - carbon-14, say - will at some point decay into a stable

isotope nearby. (Radioisotopes)

In this case, one of the neutrons in carbon-14 changes into a proton,
forming nitrogen-14. During this process, which is known as beta
decay, the nucleus emits radiation in the form of an electron and
an antineutrino.

SFT1023:INTRODUCTION TO RADIATION AND NUCLEAR PHYSICS

There are three main types of radioactive decay:

• Alpha decay
• Beta decay
• Gamma decay