Henri Becquerel Atomic Theory

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Stoichiometry: Calculating Relative Quantities in a Gas or Solution

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:04 Radioactivity and…
  • 1:50 Becquerel's Atomic Theory
  • 3:59 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Betsy Chesnutt

Betsy teaches college physics, biology, and engineering and has a Ph.D. in Biomedical Engineering

Henri Becquerel made an important contribution to our understanding of atomic theory when he discovered the existence of radioactivity. In this lesson, learn about him and his amazing discovery.

Radioactivity and Henri Becquerel

You might know someone who has had radiation therapy for cancer or another disease. This is a very common treatment for a variety of medical conditions, and it harnesses the power of radioactivity. Some atoms are inherently unstable and their nuclei break down very easily. When this happens, a tiny, high energy particle is released. The process in which atomic nuclei break down and release these high energy particles is called radioactivity. The particles that they release are called radiation.

In the past century, understanding and harnessing the power of radioactivity has led to many new technologies. Although radioactivity can be used in many beneficial ways, it can also be dangerous. Exposure to radioactivity can not only treat cancer, but can actually cause cancer as well.

Although we now know a lot about how radioactivity works, it wasn't always this way. Back in 1885, no one knew that some atoms could be radioactive. The first person to conclude that atoms could be radioactive was a French scientist named Henri Becquerel.

Becquerel was born in 1852 in Paris, France. Both his father and grandfather were well known physicists and he followed them into the family business, studying physics at the Ecole Polytechnique. In 1892, Becquerel became the third member of his family to serve as chair of the physics department at the Museum of Natural History in Paris. Becquerel spent many years studying light, until a surprisingly cloudy day led to a momentous discovery.

Becquerel's Atomic Theory

Inspired by the recent discovery of X-rays, Becquerel thought that phosphorescent elements like uranium might emit some kind of penetrating radiation similar to X-rays when exposed to light. To test this idea, he placed uranium salts on top of a photographic plate that had been wrapped in black paper to protect it from the sunlight. After several hours of exposure to the sun, he noticed that the image of the uranium could be seen on the photographic plate, so he thought that the sun was causing the uranium to emit some kind of invisible radiation.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account