unit 3 electron configurations
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UNIT 3 ELECTRON
CONFIGURATIONSPart B
Bohr’s Model of Hydrogen
WHAT HAVE WE LEARNED SO FAR?
Discharging Tubes
The Flame Test The light coming out of the excited atomic
entities is very specific to particular element!Results are quite
reproducible.
ELECTROMAGNETIC RADIATIONS (LIGHTS) COMING OUT OR BEING ABSORBED BY ATOMS INDICATE THAT THERE ARE VERY SPECIFIC ENERGY CHANGES WITHIN THE ATOMIC ENTITIES (ATOMS AND IONS).
NO NUCLEAR CHANGES HAVE EVER BEEN OBSERVED INDICATE THAT THE ENERGY CHANGES HAVE TO COME FROM ELECTRONS SURROUNDING THE NUCLEUS.
How Come?Classic Model: Electron anywhere it ‘wants’ to be
Problems with classic model:E moving through electric field will emit light & from the classic model, emitted light should have differing wavelengths
NIELS BOHR (1885 – 1962)
Increasing energy with greater distance from nucleus
BOHR’S MODEL OF HYDROGEN ATOM
Incr
easi
ng e
nerg
y
Nucleus
First-ground
Second
Third
Fourth
Fifth-excited}Further away
from the nucleus means more energy.
There is no “in between” energy
Energy Levels
quantum – quantity of energy gained or lost by an atom when electrons are excitedphoton – a quantum of lightground state – lowest energy level of an atomexcited state – a heightened state of energy in an atom
Electrons of hydrogen circle the nucleus in orbits 1. orbits have a fixed amount of energy in
the ground state. 2. orbits are a fixed distance from the
nucleus. 3. orbits furthest from the nucleus have the
greatest energy.
BOHR’S MODEL OF HYDROGEN ATOM
BOHR’S MODEL OF HYDROGEN ATOM
BOHR’S MODEL OF HYDROGEN ATOM
BOHR’S MODEL OF HYDROGEN ATOM
Bohr’s Model of Hydrogen Atom
Orbits Transitions of e between those orbits involve change in energyChange in energy (E(n2 –n1) has to be accounted for By photons
Successful in accounting for most of the H-1 emission/absorption spectral linesBUT only works for H-1
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