Radioactive Decay and Isotopes

This video tutorial by Dr. English covers the basics of nuclear chemistry, focusing on half-life and radioactivity. It explains radioactive decay, the concept of half-life, and how to use Table N for understanding decay modes. The tutorial includes visual mapping of half-life, graphical analysis of decay curves, and practice problems to reinforce learning. Key examples include isotopes like iodine-131 and carbon-14, demonstrating calculations and decay processes.

What is the atomic number at which elements start to be considered naturally radioactive?

• 83

• 82

• 79

• 85

Which of the following factors does NOT affect the rate of radioactive decay?

• Temperature

• Concentration

• All of the above

• Pressure

What is the half-life of iodine-131?

• 4.47 billion years

• 8.21 days

• 1.5 * 10^-14 seconds

• 5,715 years

What information does Table N provide about isotopes?

• Atomic number

• Half-life and decay mode

• Chemical properties

• Electron configuration

If a radioactive element has a half-life of 2 years, how much of a 100g sample remains after 8 years?

• 6.25g

• 12.5g

• 50g

• 25g

How many half-lives have passed if a 1g sample of carbon-14 is reduced to 0.125g?

• 1

• 2

• 3

• 4

What is the half-life of an isotope if its decay curve shows a reduction from 140g to 70g in 15 years?

• 20 years

• 5 years

• 10 years

• 15 years

What fraction of a strontium-90 sample remains after 87.3 years, given its half-life is 29.1 years?

• 1/2

• 1/4

• 1/8

• 1/16

Compared to strontium-90, radium-226 has a longer half-life and a different decay mode. What is the decay mode of radium-226?

• Positron emission

• Beta decay

• Alpha decay

• Gamma decay

How many days does it take for an 80g sample of iodine-131 to decay to 1.25g, given its half-life is 8.21 days?

• 24.63 days

• 32.84 days

• 48.1 days

• 64.2 days