The state of an atom or ion, including aluminum (Al), can be described using quantum numbers. Quantum numbers are used to specify the energy levels, orbital shapes, and orientations of electrons in an atom. The four quantum numbers are:
Principal Quantum Number (n): It defines the energy level or shell in which an electron is present. It takes integer values starting from 1 (1, 2, 3, etc.). The higher the value of n, the higher the energy level. In the case of aluminum, the electron configuration is [Ne] 3s² 3p¹, so the outermost electron is in the third energy level (n = 3).
Azimuthal Quantum Number (l): It determines the shape of the orbital and the subshell in which the electron resides. It can have values ranging from 0 to (n-1). The corresponding subshell letters are s (0), p (1), d (2), f (3), and so on. In the case of aluminum, the outermost electron is in the p subshell, so the azimuthal quantum number is 1 (l = 1).
Magnetic Quantum Number (ml): It describes the orientation or spatial distribution of an orbital within a subshell. It can take values from -l to +l, including zero. In the case of aluminum, since the electron is in the p subshell (l = 1), the possible values of ml are -1, 0, and 1.
Spin Quantum Number (ms): It describes the intrinsic angular momentum or "spin" of an electron. It can have two values: +1/2 or -1/2, representing the two possible spin orientations. This quantum number does not depend on the other quantum numbers.
Therefore, using quantum numbers, the state of the outermost electron in aluminum (Al) can be described as follows:
- Principal Quantum Number (n): 3
- Azimuthal Quantum Number (l): 1
- Magnetic Quantum Number (ml): -1, 0, or 1
- Spin Quantum Number (ms): +1/2 or -1/2
Note: The quantum numbers provided here represent the state of a single electron in an isolated aluminum atom. However, in reality, aluminum forms a solid and participates in chemical bonding, so the quantum numbers of individual electrons may be influenced by the presence of neighboring atoms.