15. the planetary model of the atom pictures electrons orbiting the atomic nucleus much as planets orbit the sun. in this model you can view hydrogen, the simplest atom, as having a single electron in a circular orbit 1.06×10−10m in diameter. (a) if the average speed of the electron in this orbit is known to be 2.20×106m/s, calculate the number of revolutions per second it makes about the nucleus. (b) what is the electron’s average velocity?

a) 6.6 * 10^15 (1/s)

b) 0 m/s

Explanation:

Hi!

a)

In order to complete a revolution the electron must travel a distance d, where d is the perimeter of the circular orbit:

d =  π(1.06*10^-10 m) = 3.33 * 10^-10 m

Therefore, the number of revolutions per second the electron makes about the nucleus is:

n = (2.20×10^6m/s) / d = 0.66 * 10^16 (1/s)

b)

Since the electron is travelling in a circular orbit, the average velocity must be zero. That is because the velocity is a vector and the direction of the velocity at one point on the circle is opposite at an opposite point of the same circle. When adding these two (arbitrary points) they will cancel each other

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.