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## Half life

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**Half life**What is the half life of an element and why is this important? Starter: 1024 competitors enter a tournament. Each round half of them are eliminated. Sketch points on a graph to show how many competitors are left after each round.**Starter**. x 1024 x Entrants 512 x 256 0 1 2 3 4 5 6 7 8 9 10 After Round**Radioactivity**Look at the graph. 1) describe what the half life is. What is the half life of this chemical?**Radioactive Half-life**• Radioactive half-life is the average time taken for the activity of a sample to halve.**What is the half life of radon-220?**Could be a %age**Half life Graph 2**• Take a chocolate finger. • Use the chocolate finger to point on your graph. • Measure and eat exactly 1 half of the chocolate finger. • Move the finger along 1 big square and use the top of the finger to draw the next point. • Half again and repeat**Length of Chocolate Finger**Time (AU)**The Half Life Game**• Throw 50 skittles into a tray. • Remove those with the S facing upwards. • Record how many you are left with. • Repeat until you have done this 10 times OR have none left. • Draw a graph and work out the half life.**Record your data, use it to plot a graph.**Activity of skittles (not decayed) What does this show you about how elements decay? Time (AU)**Half Life of Elements**• Work out which element you have been given using the Half Life Challenge. • Done? What sort of decay is it? • Write an equation. • Too easy? • Do 1 more and compare the 2 elements. How similar are they?**How is this useful**• Medical -**Task – ppt 2**• use the graph provided to work out the age of the objects that were found in an archaeological dig.