Question

The principal quantum number determines _____ of the orbital.

• A. energy
• B. momentum
• C. size
• D. charge

Answer 1

Answer: (A)

energy

The principal quantum number, n (the energy level)

• determines the size of an orbital (larger n = bigger orbitals)

• largely determines the energy of the orbital (larger n = higher energy)

• can take on integer values n = 1, 2, 3, ...,

• all electrons in an atom with the same value of n are said to belong to the same principle energy level

The azimuthal quantum number, l (the sublevel)

• designates the overall shape of the orbital within a shell

• affects orbital energies (larger = higher energy)

• all electrons in an atom with the same value of are said to belong to the same sublevels

• only integer values between 0 and n-1 are allowed

• sometimes called the orbital angular momentum quantum number

• spectroscopists use the following notation for sublevels

The magnetic quantum number, m (the orbital (box) the electron is in)

• determines the orientation of orbitals within a sublevel.

• does not affect orbital energy (except in magnetic fields!)

• only integer values between -l and +l are allowed

• the number of m values within a sublevel is the number of orbitals within a sublevel

The spin quantum number, ms (the direction of the arrow)

• several experimental observations can be explained by treating the electron as though it were spinning

• spin makes the electron behave like a tiny magnet

• spin can be clockwise or counterclockwise

• spin quantum number can have values of $+1/2$ or $-1/2$ (arrow up or arrow down)