1.2-STABLE AND UNSTABLE NUCLEI Flashcards
What does a stable isotope have?
nuclei that does not disintegrate, so there must be a force holding them together
What is the force holding the protons + neutrons together in the nuclei called?
strong nuclear force
Why is the strong nuclear force called the ‘strong nuclear force’?
because it overcomes the electrostatic force of repulsion between the protons in the nucleus and keeps the protons and neutrons together
What is the range of the strong nuclear force?
no more than about 3-4 femtometres (fm)
What do 1 fm equal to in m?
1 fm = 10^(-15)m
What is the range of the strong nuclear force about the same as?
diameter of a small nucleus
What is the range of the electrostatic force between two charged particles like?
has an infinite range (although it decreases as the range increases)
How does the strong nuclear force effect protons and neutrons?
it has the same effect between two protons as it does between two neutrons or a proton and neutron
From what range is the strong nuclear force an attractive for?
from 3-4 fm down to about 0.5 fm
What happens to the strong nuclear force when the separation is smaller than 3-4 fm to 0.5fm?
it is repulsive force that acts to prevent neutrons and protons being pushed into each other
What do naturally occurring radioactive isotopes release?
3 different types of radiation:
alpha, beta, gamma
What does alpha radiation consist of?
alpha particles which each comprise two protons and neutrons
What is the proton number and mass number of an alpha particle?
proton number - 2
mass number - 4
What happens to an unstable nucleus of an element X when it emits an alpha particle?
its nucleon number decreases by 4 and its atomic number decreases by 2
What happens as a result of the alpha particle being emitted? (element)
the product nucleus belongs to a different element Y
What does beta radiation consist of?
fast-moving electrons
What is the charge and mass of a beta particle like?
its charge is equal and opposite to that of the proton
its mass is much smaller than the proton’s mass
Why does an unstable nucleus of an element X emit a beta particle?
this happens as a result of a neutron in the nucleus changing into a proton. the beta particle is created and is emitted instantly
What else is emitted with the beta particle?
an antiparticle with no charge, called an antineutrino
How does the beta particle being emitted affect the element X?
atomic number decreases by 1 but the nucleon number stays the same
What happens to the product nucleus after beta particle being emitted?
belongs to a different element Y
What type of nuclei undergo beta decay?
nuclei that have too many neutrons
What is gamma radiation?
electromagnetic radiation emitted by an unstable nucleus
What can gamma radiation pass through?
thick metal plates
