Lecture 5 + 6 - The Electronic Configuration of the Atom Flashcards
what is quantum theory?
the theoretical basis of modern physics that explains the nature and behaviour of matter and energy on the atomic and subatomic level
what is wave-particle duality?
light can behave ad if made up of photons with energy depending on frequency
what is the uncertainty principle?
you can never know both the exact location and velocity of a subatomic particle at the same time
what is the hydrogen spectrum?
- electrons in an atom are in stable energy levels
- absorption of a photon of light allows an electron to jump up to a higher level
- jumping down to a lower level emits a photon of light
- measuring the energy of the photon allows the energy difference between levels to be determined - shows that energy levels are not equally spaced
what is the first ionisation energy?
the energy required to remove one mole of electrons from one mole of gaseous atoms in their ground electron configuration to form one mole of gaseous positive atoms
what is first electron affinity?
the energy required to add one mole of electrons to one mole of gaseous atoms in their ground state to form one mole of gaseous negative atoms
what is the trend for atomic size across the periodic table?
increases down the group, decreases across the period
what is the trend for first ionisation energy across the periodic table?
Decreases down the group, increases across the period
what is the trend in first electron affinity across the periodic table?
- becomes less negative down the group
- becomes more negative across the period
what are the four quantum numbers?
- Principal (n)
- Azimuthal (l)
- Magnetic (m)
- Spin (s)
what is an orbital?
a region in space where there is a given 95%probability of finding a particular electron
Describe principle energy levels
- Referred to by K,L,M
- They correspond to principal quantum number
- Known as shells and shells have multiple orbitals except n=1
Describe principal quantum numbers (n)
- higher n, the further away the electron from the nucleus
- higher n, higher energy electrons, less tightly held so easier to remove
- n can hold 2n^2 electrons
Describe azimuthal quantum numbers (l)
indicates which sub shell the electrons are in s- l=0 p- l=1 d- l=2 etc maximum number of electrons = 2(2l+1)
what shape is l=0?
spherical
what shape is l=1?
dumbbell
what shape is l=2?
more complex
what shape is l=3?
still more complex
Describe Magnetic quantum numbers
- identifies the orientation of individual orbitals within a sub shell
- can have a value between -1 to +1 so total number of m value is (2l+1)
Describe spin quantum numbers
- defines the rotation of an electron about its own axis
- it can have two values +1/2 or -1/2
- two electrons in the same orbital must have opposite spin
what is the aufbau principle?
electrons enter the lowest available energy level first
what is Hund’s rule of maximum multiplicity?
when in orbitals of equal energy electrons will try to remain unpaired, minimises repulsion in the system so it is more stable
what is Heisenbergs uncertainty principle?
you cannot determine the position and momentum of an electron at the same time
what is the Pauli exclusion principle?
no two electrons can have the same four quantum numbers, only two electrons can go in each orbital providing the are of opposite spin
