Radioactivity & Particles (7.1-7.26) Flashcards
What are atoms made of?
Protons, neutrons and electrons
Atomic number is…
the number of protons in the nucleus of an atom
Mass number is…
the total number of protons and neutrons in the nucleus of an atom
What is an isotope?
An atom of the same element that have same number of protons (atomic number) and different number of neutrons (different mass number).
Three types of ionising radiation
Alpha (α), Beta (β) and Gamma (γ)
What is ionisation?
Ionisation is when an atom loses or gains an electron, causing it to become an ion (an atom which is positively or negatively charged)
Alpha (α)
- Strong ionisng
- few centimetres in air
- stopped by paper
- nature of radiation is helium nucleus
Beta (β)
- Moderate ionisng
- 1m in air
- stopped by aluminium (5mm)
- nature of radiation is fast moving electron
Gamma (γ)
- Very weak ionisng,
- 1km in air
- stopped by lead (10cm)
- nature of radiation is electromagnetic wave
Effects of Alpha decay
- 2 protons and 2 neutrons are lost
- Mass number decreases by 4
- Atomic number decreases by 2
Effects of Beta decay
- 1 neutron is converted to an electron (lost from the atom) and proton
- Mass number is unchanged
- Atomic number increases by 1
Effects of Gamma decay
- Energy is lost from an atom in the form of an electromagnetic wave
- Mass number is unchanged
- Atomic number is unchanged
What can detect ionising radiation?
Ionising radiation can be detected by photographic film or a Geiger-Müller
- Counter connected to geiger-müller
- Radiation will cause photographic film to darken
Background radiation from earth and space
- Radon in air
- Graint in rocks
- Cosmic rays
- Medical equipment
- Food and drink
Does a radioactive source decreases over a periodof time?
The activity of a radioactive source decreases over a period of time and is measured in becquerels