Topic 1: Atomic Structure
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Hydrogen atoms … and … energy at … . These are … for different atoms
absorb emit certain discrete lines differernt
Equation that predicts the energies of hydrogen lines
Rydberg equation wavenumber = 1/λ = RH(1/(n1)^2 – (1/n2)^2) (n1 + n2 numbers subscript)
Electrons in atoms occupy discrete …
energy levels (energy levels said to be quantized)
What did the quantum theory suggest about atoms at the atomic scale?
Behave differently than larger species
Bohr atomic structure
Central nucleus with electrons orbiting at specific radii Defining energy levels for electrons
Equation linking Rydberg equation and Bohr model is … It shows …
En = -R/n^2 (Works well for hydrogen) The energy of an orbital
de Broglie suggested
All matter processes characteristics of waves and particles
Does the electron have properties of a wave or particle?
both waves (diffracted by a crystal lattice) particles (mass)
What did de Broglie consider electrons in orbitals as behaving like? Hence the electrons can only have …
Standing waves Certain energies
Standing waves can be described like …
plucking a guitar string
Following de Broglie’s work, Erwin Schrödinger used complex mathematics to describe the behaviour and energies of objects at the … The mathematical solution of Schrödinger’s wave equation gives … that correspond to the … and describe …
atomic scale wave functions energy levels/atomic orbitals the nature of electrons in those orbitals
The 4 quantum numbers are: …
n = principle quantum number ℓ = angular momentum quantum number mℓ (subscript) ms (subscript) = electron spin angular momentum quantum number
n characteristics
integer value (1,2,3,4 …) defines energy of orbitals
ℓ characteristics
takes values (0,1,2,…(n-1)) describes shape of orbital 0 = s 1 = p 2 = d 3 = f
mℓ (subscript) characteristics
takes values (-ℓ,…0,…+ℓ )
ms (subscript) characteristics
takes values (–1/2 or +1/2) results from electron spinning on own axis (clockwise / anticlockwise)
Heisenberg’s Uncertainty Principle means we can’t … What does this mean for electrons in orbitals?
know all things about an electron Atomic orbitals have to be considered as regions in space where an electron is likely to be found. They’re viewed as electron clouds showing the probability of the electron being at any given point
Why is it useful to know the probability of finding an electron at a given radius from the nucleus
judge how tightly an electron is held by the nucleus
The radial distribution function gives
the probability of finding an electron at a distance from the nucleus
Orbitals … when n increases
increase
ns orbitals have … radial nodes
n-1
s-orbitals are … while p- and d-orbitals are … This is due to the … values
symmetrical directional mℓ (subscript)
2 types of nodes
radial nodes nodal planes
total number of nodes =
n-1