T4 - Atomic structure Flashcards
Radius of atom?
1 × 10^-10m
Radius of nucleus?
1 x 10^-14m
Which electrons shell have higher energy?
electron shell further from nucleus
What happens to electron when atom absorbs electromagnetic radiation?
moves to high electron shell
What happens to electron when atom emits electromagnetic radiation?
moves to lower electron shell
What is an isotope?
Atoms of the same element that have different numbers of neutrons
What is radioactive decay?
when the nucleus gives out radiation to become more stable
Feature of radioactive decay?
its a random process
What is activity?
rate at which a source of unstable nuclei decay
What is activity measured in?
becquerel(Bq)
What is the count rate?
the number of decays recorded each second by a detector
Types of radiation? x4
-alpha particle
-beta particle
-gamma ray
-neutrom
What is an alpha particle?
two neutrons and two protons
which nucleus is the alpha particle same as?
helium nucleus
What is a beta particle?
a high speed electron ejected from the nucleus as a neutron turns into a proton
What is a gamma ray?
electromagnetic radiation from the nucleus
How far can alpha paricles travel?
5cm
How far can beta paricles travel?
15cm
How far can gamma rays travel?
several metres
What are alpha particles stopped by?
a sheet of paper
What are beta particles stopped by?
few millimetres of aluminium
What are gamma rays stopped by?
several centimetres of lead
Ionising power of alpha particles?
very strongly ionising
Ionising power of beta particles?
quite strongly ionising