(b) Atomic orbitals, electronic configuration and the periodic table

how do electrons behave in an atom

as standing (stationary) waves

what are features of the waves

vibrate in time but do not move in space. There are different sizes and shapes of standing wave possible around the nucleus, known as orbitals

how many electrons can an orbital hold

a maximum of two electrons

what is quanta

the fixed energy electrons have in an atom

what is the principle quantum number (n)

indicates the main energy level for an electron and is related to the size of the orbital

what is the angular momentum quantum number (l)

determines the shape of the subshell and can have values from zero to n −1

what is the magnetic quantum number (ml)

determines the orientation of the orbital and can have values between −l and +l

what is the spin magnetic quantum number (ms)

determines the direction of spin and can have values of +1/2 or -1/2

what is the aufbau principle

electrons fill orbitals in order of increasing energy

what is the Hund's Rule

when degenerate orbitals are available, electrons fill each 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

In an isolated atom what are the orbitals within each subshell

degenerate

what happens to the ionisation energy as the electronic configuration becomes stable

increases

what does the variation in first ionisation energy for the first 36 elements relate to

the stability of the electronic configuration

what can VSEPR (valence shell electron pair repulsion) theory can be used for

to predict the shapes of molecules and polyatomic ions

how are electron pairs arranged

to minimise repulsion and maximise separation

when is a covalent bond formed

when atomic orbitals overlap to form a molecular orbital

what is a dative covalent bond

formed when one atom provides both the electrons that form the bond

what is the arrangement of the electron pairs if the total number of electron pairs is 2

linear

what is the arrangement of the electron pairs if the total number of electron pairs is 3

trignoal

what is the arrangement of the electron pairs if the total number of electron pairs is 4

tetrahedral

what is the arrangement of the electron pairs if the total number of electron pairs is 5

trigonal bipyramidal

what is the arrangement of the electron pairs if the total number of electron pairs is 6

octahedral

what is the order of strength of repulsion in electron pairs

l-l > l-b > b-b