Watch alpha particles escape from a polonium nucleus, causing radioactive alpha decay. See how random decay times relate to the half life.

Biology is designed for multi-semester biology courses for science majors. It is grounded on an evolutionary basis and includes exciting features that highlight careers in the biological sciences and everyday applications of the concepts at hand. To meet the needs of today’s instructors and students, some content has been strategically condensed while maintaining the overall scope and coverage of traditional texts for this course. Instructors can customize the book, adapting it to the approach that works best in their classroom. Biology also includes an innovative art program that incorporates critical thinking and clicker questions to help students understand—and apply—key concepts.

By the end of this section, you will be able to:Define matter and elementsDescribe the interrelationship between protons, neutrons, and electronsCompare the ways in which electrons can be donated or shared between atomsExplain the ways in which naturally occurring elements combine to create molecules, cells, tissues, organ systems, and organisms

Using exponential decay equation to solve for relationship between k and half-life. Using semi-log plot to get graph of a straight line with slope of -k. Created by Jay.

Showing that N(t)=Ne^(-kt) describes the amount of a radioactive substance we have at time T. For students with background in Calculus. Not necessary for intro chemistry class. Created by Sal Khan.

Introduction to Exponential Decay. Using the exponential decay formula to calculate k, calculating the mass of carbon-14 remaining after a given time, and calculating the time it takes to have a specific mass remaining . Created by Sal Khan.

Carbon dating is a real-life example of a first-order reaction. This video explains half-life in the context of radioactive decay. Created by Sal Khan.

Definition of half-life and graphing the decay of phosphorus-32. Calculating how much phosphorus-32 remains after 57.2 days. Created by Jay.

This class covers basic concepts of nuclear physics with emphasis on nuclear structure and interactions of radiation with matter. Topics include elementary quantum theory; nuclear forces; shell structure of the nucleus; alpha, beta and gamma radioactive decays; interactions of nuclear radiations (charged particles, gammas, and neutrons) with matter; nuclear reactions; fission and fusion.

A few more examples of exponential decay. Practice calculating k from half-life, and calculating initial mass. Created by Sal Khan.

Writing nuclear equations for alpha, beta, and gamma decay. Created by Jay.