Atomic structure and the periodic table Flashcards
What is the relative isotopic mass?
the mass of an isotope of an atom relative to the mass of 1/12 the atom of carbon-12
What is the relative atomic mass?
The average mass of an atom relative to the mass of 1/12 of an atom of carbon-12
what is the principal quantum number (n) ?
The number given to each shell e.g. the third shell has n=3
What happens when we have 2 electrons in the same orbital?
They must have opposite spins
What is an atomic orbital?
A region around the nucleus that can hold up to 2 electrons with opposite spins
What are the different types of atomic orbitals?
S, P, D, F
Define details of S orbitals
- It has a spherical shape and every electron shell contains a single s orbital
- The size of the orbitals increase with increasing shell number
Define details of p orbitals
- There are 3 p orbitals
- They are shaped like a dumb bell
- They are orientated perpendicular to one another
- With increasing shell number, the lobes become longer and larger
How many d orbitals are there?
5
How many f orbitals are there?
7
How are electrons imagined?
As small spinning charges which rotate around their own axis in either clockwise or anticlockwise direction. The spin creates a tiny magnetic field with each pole facing up or down
What happens to electrons with the same spin?
they repel each other, known as spin-spin repulsion
What do sub shells contain?
one or more atomic orbitals
What will electrons do first?
They will occupy separate orbitals in the same sub shells to minimise this repulsion and have their spin in the same direction (known as Hund’s rule)
What will electrons do after this?
They will then pair up, with a second electron being added to the first p orbital with its spin in the opposite direction (known as Hund’s rule)
How much space does each electron occupy?
Even though there is repulsion between them, they occupy the same region of space in orbitals
What is the Pauli Exclusion principle?
all electrons in an atom must be in different orbitals or have different spins
What is the reason for the Pauli Exclusion principle?
The energy required to jump to a higher empty orbital is greater than the inter-electron repulsion so they occupy lower energy levels first
What is the aufbau principle?
Electrons enter the lowest energy orbital available
What is Hund’s rule?
Electrons prefer to occupy orbitals on their own, and only pair up when no empty orbitals of the same energy are available
What is the order the electrons fill the orbitals in?
1s - 2, 2s - 2, 2p - 6, 3s - 2, 3p - 6, 4s - 2, 3d - 10, 4p - 6