Aproton is projected toward a fixed nucleus of charge +ze with velocity vo. initially the two particles are very far apart. when the proton is a distance r from the nucleus its velocity has decreased to 1/2 vo. how far from the nucleus will the proton be when its velocity has dropped to 1/4 vo?

Explanation:

Translation:

Electrons in an atom are identified by four quantum numbers. Two electrons in one atom cannot have the same set of four quantum numbers.

This first quantum number is identified by the letter n and is named Principal quantum number. It can have only positive integer values: 1, 2,3, 4, 5, 6, 7, ...

Thus, the official name of the first quantum number is Principal quantum number.

The first quantum number indicates the main energy level which is related with the size of the orbitals: the larger the principal quantum number the farther the electron cloud is from the atomic nucleus. Thus, it is also used the name energy level to refer to the first quantum number.

Notice that the principal quantum number is also the number of the period of the element in the periodic table.