Final answer:
When an electron collides with a simple atom, it can cause the atom to become excited. The kinetic energy of the electron can be calculated using the formula KE = (1/2)mv^2. The collisionally excited atom can absorb an amount of energy equal to the difference between the allowed energies.
Step-by-step explanation:
The allowed energies of a simple atom are 0.0 eV, 4.0 eV, and 6.0 eV. When an electron traveling at a speed of 1.7×10^6 m/s collides with the atom, it can cause the atom to become excited. The kinetic energy of the electron can be calculated using the formula: KE = (1/2)mv^2, where m is the mass of the electron and v is its velocity. The collisionally excited atom can absorb an amount of energy equal to the difference between the allowed energies. In this case, that would be 6.0 eV - 4.0 eV = 2.0 eV.