Elements, Atoms & The Periodic Table Flashcards
What are electrons in orbitals characterised by?
4 quantum numbers
What are the four quantum numbers?
n, l, ml, ms
What is n in respect to electron quantum numbers?
The principal quantum number
What does the principle quantum number tell you?
It tells you how far the electron is from the nucleus (i.e the energy level/shell of an electron in an atom)
How does the period in the periodic table relate to the principal quantum number?
In the S and P-blocks, the principle number is the same as the period number.
In the D-block it is the period number subtract 1
What is l in respect to electron quantum numbers?
l is the angular momentum quantum number
What does the angular momentum quantum number tell you?
It defines the radial spatial distribution of the wavefunction, i.e what type/shape of subshell the electron is in
What are the possible values of l?
The value of l is limited by n. It must be at least n-1. When n is 3, l can be 2, 1 or 0
Which subshell does each value represent in l quantum numbers?
0 = s
1 = p
2 = d
3 = f
What is ml in respect to electron quantum numbers?
ml is the magnetic quantum number
What does the magnetic quantum number tell you?
It defines the orientation of the wave function, i.e which orbital within a subshell the electron is found
What are the possible values of ml?
The value of ml is limited by l.
It can be anywhere between + and - l
For example, if l = 1, ml can be -1, 0 or +1
How many orbitals are there in s-orbitals?
1, so there is only one value for ml (0)
How many orbitals are there in p-orbitals?
3, so there are three values for ml (-1, 0, 1)
How many orbitals are there in d-orbitals?
5, so there are five values for ml (-2, -1, 0, 1, 2)
How many orbitals are there in f-orbitals?
7, so there are seven values for ml (-3, -2, -1, 0, 1, 2, 3)
What does ms represent?
The spin quantum number
What does the spin quantum number tell you?
The direction of spin on the electron
What is the Pauli exclusion principle?
Electrons fundamentally cannot occupy the same space. Only electrons can occupy any one orbital, and one must spin up and one spin down.
Therefore, no two electrons in the same atom can share the same set of quantum numbers
What are the possible value of ms?
+1/2 (spin up) or -1/2 (spin down)
What is the Aufbau principle?
Electrons are found in the lowest available energy orbital
What is Hund’s rule?
With degenerate orbitals, the lowest energy configuration is achieved by putting electrons in different orbitals, with parallel spins
Why is the lowest energy configuration achieved by putting electrons in different orbitals, with parallel spins?
- Electrons in different orbitals are spatially separated
- Electrons with the same spin (up, up) do a better job of avoiding each other than electrons with opposite spin (up, down)