Unit 1 Inorganic Chemistry: Key Area 2 - Atomic orbitals, electronic configurations and the periodic table Flashcards
How can the discrete lines in an atomic spectra be explained?
The discrete lines observed in atomic spectra can be explained if electrons, like photons, also display the properties of both particles and waves.
What are orbitals defined as?
An area where there is a 90% probability of finding an electron
What are the 4 quantum numbers?
- Principle Quantum Number (n)
- Angular Momentum Quantum Number (l)
- Magnetic Quantum Number (m)
- Spin Magnetic Quantum Number (ms)
What is the meaning of the Principle Quantum Number?
Energy level
What is the meaning of the Angular Momentum Quantum number?
shape of the orbital
What is the meaning of the Quantum number?
orientation
What is the meaning of the Spin magnetic Quantum number?
Electron spin
What is the fixed amount of energy of electrons within atoms called?
quanta
What does the principle quantum number tell you about an atom?
The average relative distance of the electron from the nucleus. Is measure in n= 1,2,3,4…
What does a higher value of n in the principle quantum number indicate?
The higher the value of n, the higher the potential energy associated with the shell and electrons are easier to remove from an atom
If the value of n is 1, what is the value of l and the subsequent sub-shell?
l=0 and 1s
If the value of n is , what is the value of l and the subsequent sub-shell?
l = 0/1 and 2s/2p
If the value od n is 3, what is the value of l and the subsequent sub-shell?
l = 0/1, and 3s/3p, 3d
If the value od n is 4, what is the value of l and the subsequent sub-shell?
l = 0/1, 2/3 and 4s/4p, 4d/4f
How many atomic orbitals are there within a s sub shell?
1
How many atomic orbitals are there within a p sub shell?
3
What are the key features of the s orbital?
- spherical
- the s orbital in the first shell is smaller than the s orbital in the second shell
What are the key features of the p orbital?
- each p orbital has two lobes
- three p orbitals have DEGENERATE (have the same energy as the other).
- they are aligned along perpendicular axes
What are different about d orbitals?
the five d orbitals are DEGENERATE with each other but have higher energies than the s and p orbitals in the same shell
What MUST be known about orbitals?
- The shapes of s and p orbitals
- Max number of electrons in any orbital
- Recognise d orbitals from diagrams
- Know that d has a different shape
If the value of l is 0/1, what is the value of m and the type of atomic orbital?
m -1,0,+1 and 2s/2p
If the value of l is 2, what is the value of m and the type of atomic orbital?
m = -2,-1,0,+1,+2 and 3s,3p,3d
What value of s in the spin quantum number represents clockwise rotation?
S = +1/2
What value of s in the spin quantum represents an anti- clockwise rotation?
S = -1/2
What is the maximum amount of electrons an orbital can hold?
2
In any orbital containing 2 electrons what must happen?
The electrons must be paired with the spins opposed represented as a box with a arrow pointing up and other pointing down, where the box represents an orbital
What is the Pauli Exclusion Principle?
The Pauli Exclusion Principle states that - No two electrons in the same atom can have the same set of four quantum numbers. (no orbital can hold more than 2 electrons and the two electrons must have opposite spins)
What are the three rules used to determine in which orbital, electrons of an element are located?
- The Aufbau Principle
- Hund’s Rule
- The Pauli Exclusion Principle
What does the Aufbau principle state?
That electrons fill the orbitals of increasing energy, meaning that the electrons will fill the orbitals starting with the orbital of lowest energy).
What does Hund’s rule state?
For degenerate orbitals, electrons will fill each orbital singly and with parallel spins, before pairing up to fill the orbitals.
What happens to the sub-shell as the principle number increases?
The sub-shell will increase in energy.
What is different about the 3d shell?
The 3d shell has greater energy than the 4s sub-shell.
What is the ionisation energy?
The energy required to remove one mole of electrons from one mole of atoms in the gaseous state.
Why between Be and B as well as Mg and Al is there a decrease in ionisation energy?
A full sub shell is a stable arrangement. For an element begins a new sub shell there is a decrease in stability.
Why between N and O as well as P and S is there a decrease in ionisation energy?
A half full sub shell is also a relatively stable arrangement.
How do molecules cope with excess electrons?
Extra orbitals are needed which come from empty d orbitals
In order to predict molecular shape, what must be considered?
That all outer shell electrons (valence electrons) of the central atom repel each other. Must also consider bonding and non-bonding electron pairs.
What is the process of predicting molecular shape called?
The Valence Shell Electron Pair Repulsion theory (VSEPR)
In a neutral atom, what is the equation for electron pairs?
EP = no. of outer electrons + no. of bonding electrons / 2
What is the equation for electron pairs with ions?
EP = no. of outer electrons + no. of bonded electrons (+ an electron for each negative charge and - an electron for each positive charge) / 2
What is descending order of repulsion effect?
- non bonding / non bonding
- non bonding / bonding
- bonding / bonding
