Atomic Orbitals, Electronic Configurations and the Periodic Table Flashcards
What is an atomic orbital?
An atomic orbital is an area in an atom where there is a high probability of finding an electron (90% or more).
What does quantised mean?
Electrons can only hold fixed amounts of energy known as quanta. Therefore electrons can be defined in terms of quantum numbers.
What are the 4 quantum numbers?
1) Principle Quantum Number (n) - related to the size of the orbital. The higher the value of n, the further away from the nucleus the orbital is.
2) Angular Momentum Number (l) - related to shape of orbital. Shapes of orbitals are s,p,d and f. When the value of l is 0, the shape of the orbital is s, when it is 1 the orbital is p and so on.
3) Magnetic Quantium Number (m) - represents the orientation of any non-spherical orbital. The p orbitals have m values of -1, 0, +1, and the d orbitals have values of -2, -1, 0, +1, +2.
4) Spin Quantum Number (s) - indicates the spin of an electron in an orbital (1/2,-1/2 etc).
What 2 properties can electrons act as?
Waves and particles.
What is an s orbital?
An s orbital is spherical in shape and is in every subshell. The first subshell only holds an s orbital, the second subshell holds an s orbital and 3 p orbitals and so on. The size of these orbitals increase the further away from the nucleus they are.
What does degenerate mean?
Degenerate means the orbiatals have the same energy.
What is a p orbital?
There are 3 different p orbitals; one lying on the x axis, one on the y axis and one on the z axis. This means they can hold a maximum of 6 electrons (2 in each orbital). The p orbitals are dumbbell-shaped and are found in every subshell except the first one. They have higher energies than the s subshell.
What is a d orbiatal?
There are 5 different d orbitals; one lying on the z axis (weird shaped one), one lying on the x and y axes, one lying between the x and y axes, one lying between the y and z axes, and one lying between the x and z axes. Therefore the d orbitals can hold a maximum of 10 electrons and are found in all orbitals except the first 2 They are double dumbell shaped except the one on the z axis and have higher energies than the s and p orbitals.
What is the Pauli Exclusion Principle?
States that ‘no two electrons in the same atom can have the same set of four quantum numbers.’ This means no orbital can hold more than 2 electrons and the 2 electrons must have opposite spins.
What is the Aufbau Principle?
States that electrons must fill the orbitals in order of increasing energy.
What is Hunds Rule?
States that when degenerate orbitals are availble, electrons fill each orbital singly before pairing up.
Does the 4s orbital have a higher energy than the 3d orbital?
No, which means the electons fill the 4s subshell first before filling the 3d subshell. However, when electrons are lost, they are lost from the 4s subshell first.
What is Electronic Configuration?
This is similar to electron arrangement but it shows the subshells the electrons occupy instead of just number. of electrons. Electronic configuration can either be written as orbital box notation or spectroscopic notation.
What is orbital box notation?
Orbital box notation is when the orbitals are shown as boxes in order of increasing energy. The electrons are represented by arrows in the boxes and the arrows point in opposite directions to show the opposite spins.
What is spectroscopic notation?
Spectroscopic notation is where the orbitals and the subshell they are in is written and the number of electons in the orbital is shown in the top right corner. For example, lithium has an electron arrangement of 2,1 so its spectroscopic notation would be 1s^2 2s^1.
