1.2 atomic orbitals, electronic configurations and the periodic table Flashcards
how can the discrete lines observed in atomic spectra be explained
if electrons, like photons, also display the properties of both particles and waves
what do electrons behave as in atoms
stationary waves
what are stationary/standing waves
waves that vibrate in time but do not move in space
what are orbitals
the different sizes and shapes of standing waves possible around a nucleus
how many electrons can an orbital hold maximum
2
what is quanta
a fixed amount of energy that the electrons within atoms have
what are the four quantum numbers
- the principle quantum number
- the angular momentum quantum number
- the magnetic quantum number
- the spin magnetic quantum number
what is the principle quantum number shortened
n
what is the angular momentum quantum number shortened
l
what is the magnetic quantum number shortened
ml
what is the spin quantum number shortened
ms
what is the principle quantum number
this indicates the main energy level for an electron and is related to the size of the orbital
what is the angular momentum quantum number
this determines the shape of the subshell and can have values from zero to n-1
what is the magnetic quantum number
this determines the orientation of the orbital and can have values between -l and +l
what is the spin magnetic number
this determines the direction of spin and can have values of +1/2 or -1/2
what three rules are electrons within atoms arranged according to
- the aufbau principle
- hund’s rule
- the pauli exclusion theory
what does the aufbau principle state
electrons fill orbitals in order of increasing energy
what does hund’s rule state
when degenerate orbitals are available, electrons fill each singly, keeping their spins parallel before spin pairing starts
what does the pauli exclusion principle state
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 are the orbitals within each subshell of an isolated itom described as
degenerate
what is the relationship between electronic configuration and ionisation energy
the more stable the electronic configuration, the higher the ionisation energy
what is VSEPR
valence shell electron pair repulsion
how do you calculate the number of electron shells
valence of central atom + number of atoms attached - charge of ion divided by 2
how are electron pairs arranged
to minimise repulsion and maximise separation
how many electron pairs for a linear shape
2
how many electron pairs for a trigonal planar
3
how many electron pairs for a tetrahedral shape
4
how many electron pairs for trigonal bipyramidal
5
how many electron pairs for octahedral
6
what shape is a molecule with 2 electron pairs
linear
what shape is a molecule with 3 electron pairs
trigonal planar
what shape is a molecule with 4 electron pairs
tetrahedral
what shape is a molecule with 5 electron pairs
trigonal bipyramidal
what shape is a molecule with 6 electron pairs
octahedral
how are the shapes of molecules or polyatomic ions determined
the shapes adopted by the atoms present based on the arrangement of electron pairs
