chemistry - 1.2 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 an atom?
‘Stationary waves’, waves that vibrate in time but do not move in space.
What are orbitals?
Different sizes and shapes of standing wave possible around the nucleus.
What are the different shapes of orbitals identified as?
s, p, d and f
What do electrons within atoms have?
Fixed amounts of energy called quanta.
How can you describe any electron in an atom?
Using four quantum numbers.
What does the principal quantum number ‘n’ indicate?
The main energy level for an electron and is related to the size of the orbital.
What does the angular momentum number ‘l’ determine?
The shape of the sub shell and can have values from zero to n-1.
What does the magnetic quantum number ‘ml’ determine?
The orientation of th orbital and can have values between - l and + l.
What does the spin magnetic quantum number ‘ms’ determine?
The direction of spin and can values of +1/2 or - 1/2.
What is the aufbau principle?
Electrons fill orbitals in order of increasing energy.
What is 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 is the periodic tablet subdivided into?
Four blocks (s, p, d and f) corresponding to the outer electronic configurations of the elements within these blocks.
