1.2 Atomic orbitals, electronic configurations and the periodic table Flashcards
How can the discrete lines in atomic spectra be explained?
If electrons, like photons, also display the properties of both particles and waves
How do electrons behave?
as standing (stationary) waves in an atom
Describe standing waves in an atom
- They are waves that vibrate in time but do not move in space
- There are different sizes and shapes of standing waves possible around the nucleus, known as orbitals
What is the maximum number of electrons that an orbital can hold?
2
What are the different shapes of orbitals defined as?
s, p, d and f
Describe energy of electrons in atoms
electrons have fixed amounts of energy called quanta
What is the purpose of quantum numbers?
to describe any electron in an atom
what are the 4 quantum numbers?
- Principle quantum number
- Angular momentum quantum number
- Magnetic quantum number
- Spin magnetic quantum number
Describe the principle quantum number
- n
- Indicates the main energy level for an atom and is related to the size of the orbital
Describe the angular momentum quantum number
- l
- Determines the shape of the subshell and can have values from 0->n-1
Describe the magnetic quantum number
- ml
-determines the orientation of the orbital and can have values between -l -> +l
Describe the spin magnetic quantum number
-ms
-determines the direction of spin and can have values of +1/2 or -1/2
What 3 principles are electrons arranged according to?
- aufbau principle
- Hund’s rule
- The Pauli exclusion principle
What is the aufbau principle?
Electrons fill orbitals in order of increasing energy
What is Hund’s rule?
when degenerative orbitals are available, electrons fill up singly, keeping their spins parallel before spin pairing starts
What is the Pauli exclusion principle?
No two electrons in one atom can have the same set of four quantum numbers, therefore no orbital can hold more than two electrons and these two electrons must have opposite spins.
What orbitals are degenerate?
the orbitals within each subshell
What can orbital box notation show?
the relative energies corresponding to each orbital
Where is the s block?
left
where is the p block?
right
where is the d block?
transition metals
Where is the f block
bottom
How can the variation in the first, second and subsequent ionisation energies with increasing atomic numbers be explained?
- relative stability of different subshell electron configurations.
- This provides evidence for these electronic configurations.
How can anomalies in the trend of ionisation energies be explained?
by considering the electronic configurations
Explain stability and ionisation energies
the more stable the electronic configuration, the higher the ionisation energy.
What is the special stability associated with?
half-filled and full subshells
What can VESPR be used for?
Can be used to predict the shapes of molecules and polyatomic ions
How can the number of electron pairs surrounding a central atom be found by?
-total number of outer electrons on the central atom and adding one for each atom attached
-adding an electron for each negative charge
-removing an electron for each positive charge
-dividing total by two to give total number of electron pairs
Explain electron arrangement in relation to each other
- e- pairs are negatively charged and repel each other
- they are arranged to minimise repulsion and maximise separation
Atomic shape for 2 electron pairs?
linear
Atomic shape for 3 electron pairs?
trigonal planar
Atomic shape for 4 electron pairs?
tetrahedral
Atomic shape for 5 electron pairs?
trigonal bipyramidal
Atomic shape for 6 electron pairs?
Octahedral
How are shapes of molecules or polyatomic ions determined?
-by the shapes adopted by the atoms present based on the arrangement of electron pairs.
-electron dot diagrams can be used to show these arrangements
What is the order of electron pair repulsions in decreasing strength order?
non-bonding pair/non-bonding pair>non-bonding/bonding pair>bonding pair/bondjng pair
