ELECTRONIC STRUCTURE Flashcards
What is an orbital?
A region in space that is likely to contain an electron
1 orbital can hold up to 2 electrons
The shape of an orbital is called an electron cloud, and is in different shapes depending on the type of orbital
What are the features of s-orbitals?
Their electron cloud is in a sphere shape
In a given energy level, there is 1 s-orbital
S-orbitals are first present in the 1st energy level
As n increases, the radius of this orbital increases
What are the features of p-orbitals?
Their electron cloud is in a dumb-bell shape
There are 3 p-orbitals in an energy level
P-orbitals are first present in the 2nd energy level
As n increases, the distance between the p-orbital and the nucleus increases
What are the features of d and f orbitals?
They also have dumb-bell shapes, but the d orbital points positively diagonally in the Z axis, and the f orbital points vertically
In an energy level, there are 5 d orbitals and 7 f orbitals
D-orbitals are first present in the 3rd energy level
F-orbitals are first present in the 4th energy level
What is the arrangement of orbitals in atoms?
In the 1st energy level, there is 1 s-orbital, containing at most 2 electrons; referred to as 1s
In the 2nd energy level, there is a 2nd s-orbital and 3 p-orbitals, with 2 and 6 electrons respectively; with the p orbitals being grouped as 2p, along with 2s
In the 3rd energy level, there is a 3rd s-orbital, another 3 p-orbitals and 5 d-orbitals, with the d-orbital containing 10 electrons; the d orbitals are grouped as 3d
In the 4th energy level, the sequence continues, with 7 f-orbitals added; the f orbitals being grouped as 4f
How many electrons are in each energy level
N = 1, 2 electrons; 1s
N = 2, 8 electrons; 2s, 2p
N = 3, 18 electrons; 3s, 3p, 3d
N = 4, 32 electrons; 3s, 3p, 3d, 3f
How do electrons fill up the energy levels?
They go from lowest to highest energy levels, with s > p > d > f in terms of what sub-shells get filled up first
How do electrons fill up the orbitals?
Using the 2p sub-shell as an example:
The electrons fill up the orbitals how a bus would fill up, all empty pairs of seats take 1 person, before other people begin filling up the remaining seats in the pair
If there were only 3 electrons in the 2p orbital, each orbital would contain 1 electron, rather than one having 2 and one having 1
If there were 4, then the 1st orbital has 2 electrons, with the other 2 orbitals having 1 electron
How do electrons fill up the orbitals, when drawn?
Electrons are represented by arrows within a box
In an orbital with 2 electrons, you draw an up arrow then a down one, representing the electron’s spin
With 1 electron, do the up arrow only
How does electron structure work with ions?
The highest energy orbital will gain or lose the electrons
In Calcium (1s2 2s2 2p6 3s2 3p6 4s2), when becoming a Ca2+ ion, the electrons would go from the 4s sub-shell
In Oxygen (1s2 2s2 2p4), when becoming a O2- ion, the electrons would go to the 2p sub-shell
What is ionisation enthalpy?
The amount of energy needed to remove 1 mole of electrons from 1 mole of atoms in the gaseous state
