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Nuclear Reactions. Friday, 24 October 2014. Learning Outcomes. You should be able to: State the relative charge and mass of the constituents of an atom. State how many protons and neutrons are in a nucleus, given its mass number and its atomic number .
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Nuclear Reactions Friday, 24 October 2014
Learning Outcomes • You should be able to: • State the relative charge and mass of the constituents of an atom. • State how many protons and neutrons are in a nucleus, given its mass number and its atomic number. • Describe the origins of background radiation.
The atom!!!! • Who can draw and label an atom? • Try Lithium.
Thinking time • Can you remember why radioactivity is so dangerous? • What damage can it do to humans?
Video • A is for Atom is a video from the 1950’s that gives you info about atoms. • http://www.youtube.com/watch?v=Gi-ItrJISQE
Isotopes!! • Phet website – build an atom. • What is an isotope? • What is the difference between C12 and C14? Can you draw them to figure it out?
Decay • We know there are different versions of the same atom (isotopes) We know what an atom is.
So what is decay? Yuck boring picture!!
Radiation • Re-cap – what are the three types of ionising radiation? When these are given off we say the atom is decaying! What can you remember about them?
Demo Radioactivity • Note down a little about each type of radiation. • Remember it is unstable isotopes that decay and it is RANDOM!
What happens as a nucleus loses radiation? • Draw an alpha and beta particle
Radiation is everywhere!! Nuclear weapons testing Why? Cosmic rays x-rays Food and drink
Questions Uranium loses an alpha particle what will The new mass number be? Is this still uranium? 4 2 238 92
Questions • Have a go....... • What are the three parts of an atom called? • What is the charge of each sub-atomic particle? • What makes up the mass number of an atom? • What makes up the atomic or proton number? • What are the three types of radiation? • What is the mass of an alpha particle? • Where does background radiation come from?
Learning Outcomes • You should be able to: • State the relative charge and mass of the constituents of an atom. • State how many protons and neutrons are in a nucleus, given its mass number and its atomic number. • Describe the origins of background radiation.
Open your books...Date:Title:LO: Alpha, Beta and Gamma Radiation To learn about the different types of radiation and their properties. Don’t forget: Underline the title and date with a ruler!
Outcomes: • You must be able to state what Alpha, Beta and Gamma radiation is. • You should be able to state what the electric charge and penetrating power of each type of radiation is. • You could be able to explain how each type of radiation is affected in a magnetic field.
How can radiation be detected? Radiation is all around us – naturally occurring, and man-made sources, but it is invisible, so how do we actually know it’s there? The effects of radiation can be seen and so it can detected using instruments such as a Geiger-Müller tube. This is a device that can detect and measure radiation. Radioactivity can also be detected by the presence of photographic film, which darkens when struck by radiation. This effect lead to the initial discovery of radioactivity more than one hundred years ago.
New nucleus 3 types of ionising radiation 1) Alpha ()– an atom decays into a new atom and emits an alpha particle (2 protons and 2 neutrons – the same as the nucleus of a helium atom) Unstable nucleus New nucleus Alpha particle 2) Beta () – an atom decays into a new atom by changing a neutron into a proton and electron. The fast moving, high energy electron is called a beta particle. Beta particle Unstable nucleus 3) Gamma – after or decay surplus energy is sometimes emitted. This is called gamma radiation and has a very high frequency with short wavelength. The atom is not changed. Unstable nucleus New nucleus Gamma radiation
Penetration Power Sheet of paper Few mm of aluminium Few cm of lead
Why are some stopped? • Think of the paper as a mesh fence...
Reflect, absorb or transmit? • Not all particles are reflected. Some may be absorbed or transmitted through the substance. • But how?
Looking at the atomic scale... A material that appears to be solid has a lot of empty space within it.
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