Noadswood Science, 2012

Effects Of Alpha, Beta & Gamma Radiation On The AtomTo understand the effect of alpha, beta and gamma radiation on

the atom

Wednesday, April 19, 2023

Radioactivity AnagramsSee if you can solve the anagrams: -

DaratiionTeabNoreelctApahlStoopeiNooprtUrnotenMamagFlha LefiReggie-Rullem Buet (detects radiation)

Radioactivity AnagramsSee if you can solve the

anagrams: -Daratiion TeabNoreelct ApahlStoopeiNooprt Urnoten Mamag Flha LefiReggie-Rullem Buet

RadiationBetaElectronAlphaIsotopeProtonNeutronGammaHalf LifeGeiger-Muller Tube (detects

radiation)

AtomsUsing the periodic table work out how many neutrons,

protons and electrons and found in the following atoms: -HydrogenHeliumLithiumCarbonOxygen

Electrons

Protons and

neutrons

AtomsRemember: -

The mass number (top number) shows the number of protons + neutrons

The atomic number (bottom number) shows the number of protons (and therefore, the number of electrons)

Using the periodic table work out how many neutrons, protons and electrons and found in the following atoms: -HydrogenHeliumLithiumCarbonOxygen

OMass

numberAtomic

number

O168

Periodic Table

AtomsRemember: -

The mass number (top number) shows the number of protons + neutrons

The atomic number (bottom number) shows the number of protons (and therefore, the number of electrons)

Hydrogen: -Mass number 1 (1 proton and 0 neutrons)Atomic number 1 (1 proton & 1 electron)

Helium: -Mass number 4 (2 protons and 2 neutrons)Atomic number 2 (2 protons & 2 electrons)

OMass

numberAtomic

number

AtomsLithium: -

Mass number 7 (3 protons and 4 neutrons)Atomic number 3 (3 protons & 3 electrons)

Carbon: -Mass number 12 (6 protons and 6 neutrons)Atomic number 6 (6 protons and 6 electrons)

Oxygen: -Mass number 16 (8 protons and 8 neutrons)Atomic number 8 (8 protons and 8 electrons)

OMass

numberAtomic

number

Atoms & IsotopesAn atom is made from a nucleus surrounded by electrons –

the nucleus contains protons and neutrons

Isotopes are atoms that have the same number of protons, but different numbers of neutrons – the nuclei of some isotopes are unstable, emitting radiation and breaking down to form smaller nuclei…

Isotopes Isotopes are the atoms of an element with different

numbers of neutrons – they have the same proton number, but different mass numbers…

Look at the isotopes of hydrogen: -

1 proton; 0 neutrons; 1 electron 1 proton; 1 neutron; 1 electron 1 proton; 2neutrons; 1 electron

Radioactive DecayThe nuclei of some isotopes are unstable – they can split up

or ‘decay’ and release radiation

Such isotopes are called radioactive isotopes or radioisotopes

When a radioactive isotope decays, it forms a different atom with a different number of protons

Alpha EmissionAn α particle consists of 2 protons and 2 neutrons

When an unstable nucleus emits an α particle its atomic number goes down by 2, and its mass number down by 4

α4

2

Beta EmissionA β particle is an electron created and emitted by a nucleus

which has too many neutrons compared with protons

A neutron in its nucleus changes into a proton and a β particle – this is instantly emitted at high speed by the nucleus

The relative mass of a β particle is effectively zero, and its relative charge is -1

When an unstable nucleus emits a β particle its atomic number goes up by 1, but its mass number stays the same (the neutron has changed into a proton)

β0

-1

Gamma EmissionGamma rays are very short electromagnetic waves

Gamma rays penetrate far into materials meaning they are weakly ionising – however they are very dangerous still as they pass through materials easily so can harm from a very long distance away

Changing ElementsWhen an atom emits alpha or beta radiation, its nucleus

changes – it becomes the nucleus of a different element

This is because the number of protons in the nucleus determines which element the atom belongs to – these are the changes that occur to the number of particles in an unstable nucleus when it emits a radioactive particle: -

Changes In The Nucleus

Particles Emitted

Alpha (α) Decay

Nucleus loses 2 protons & 2 neutrons

2 protons and 2 neutrons emitted as a α particle

Beta (β) DecayNeutron in the nucleus changes into a proton

An electron is created in the nucleus, and emitted

UraniumUranium-230 nuclei emit alpha radiation and become

nuclei of thorium-226

U230

92

Th226

90

He

4

2+

The mass number is reduced by 4 (2 protons + 2 neutrons gone)

The atomic number is reduced by 2 (2 protons gone)

* The alpha particle is identical to a helium nucleus

HydrogenHydrogen-3 nuclei emit beta radiation and become nuclei of helium-3

H3

1 He

3

2 e0

-1+

The mass number stays the same (2 protons + 1 neutron)

The atomic number increases by 1 (1 protons added)

Background RadiationBackground radiation is all around us – most background radiation

comes from natural sources, while most artificial radiation comes from medical examinations, such as X-ray photographs

Natural sources – radiation is all around us, coming from radioactive substances including the ground, the air, building materials and food

Radiation is also found in the cosmic rays from space

Background Radiation – NaturalSome rocks contain radioactive substances that produce a

radioactive gas called radon.

Background Radiation – ArtificialArtificial sources of radiation include radioactive waste from

nuclear power stations, radioactive fallout from nuclear weapons testing and medical X-rays – artificial sources account for about 15% of the average background radiation dose

Balancing Nuclear EquationsAlpha and beta decays can be written as nuclear equations…

*Mass and atomic numbers must balance on each side

α decay

Balancing Nuclear EquationsAlpha and beta decays can be written as nuclear equations…

*Mass and atomic numbers must balance on each side

β decay

Summary Questions1. How many protons and neutrons are there in the nucleus

of each of the following isotopes: -

a) C

b) Co

c) U

12

6

60

27

235

92

Summary Questions2. A substance contains the radioactive isotope U which

emits alpha radiation – the product nucleus X emits beta radiation and forms a nucleus Y. How many protons and neutrons are present in the following: -

a) A nucleus of U

b) A nucleus of X

c) A nucleus of Y

238

92

238

92

Summary Answers1. How many protons and neutrons are there in the nucleus

of each of the following isotopes: -

a) C – 6 protons and 6 neutrons

b) Co – 27 protons and 33 neutrons

c) U – 92 protons and 143 neutrons

12

6

60

27

235

92

Summary Answers2. A substance contains the radioactive isotope U which

emits alpha radiation – the product nucleus X emits beta radiation and forms a nucleus Y. How many protons and neutrons are present in the following: -

a) A nucleus of U – 92 protons and 146 neutrons

b) A nucleus of X – 90 protons and 144 neutrons (has lost 2 protons and 2 neutrons)

c) A nucleus of Y – 91 protons and 143 neutrons (1 neutron changed to a proton)

238

92

238

92