Electromagnetic radiation with a frequency of 8.6 ´ 1014 hz incident on an unknown metal surface causes ejection of photoelectrons with kinetic energies of 1.3 ´ 10–19 j. what is the unknown metal?

The unknown metal is Sodium.

Explanation: Photoelectric effect happens when a metal surface is hit by a monochromatic eletromagnetic wave causing the surface to emit electrons, which is the case for question.

To determine the metal, we have to find Φ or work function (W), which is the energy necessary to detach a photoelectron from the surface:

W = hf - KE

where:

h is Planck's constant and equals 6.63. J/s;

f is the frequency of the wave;

KE is kinetic energy the electron has the instant it detaches from the surface;

W = hf - KE

W = 6.63.. 8.6. - 1.3.

W = 57.018. - 1.3.

W = 4.4. eV

The element which uses this amount of energy to detach an electron is Sodium (Na).

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.