light passed
through a prism,
broken up into an
array of colours
called a spectrum
light from a hydrogen discharge
tube, Niels Bohr found that
instead of seeing a continuous
spectrum, he saw a series of
narrow lines called an emission
line spectrum
each element
has its own
unique
emission line
spectrum.
Flame test
Explaining the evidence of the Bohr theory
1) electrons revolve around
the nucleus in fixed paths
called orbits.
2) electrons
have fixed
amount of
energy. for this
reason they are
called energy
levels.
An energy
level is defined
as the fixed
amount of
energy value
that an electron
in an atom may
have.
3)as long as
an electron is
in any one
particular
energy level it
neither gains
nor loses
energy
when an atom
absorbs
energy, it
jumps from a
lower energy
level to a
higher energy
level.
energy is lost when an electron
falls from a higher energy level to
a lower energy level.
Quantisation
the energy of an electron in a particular energy
level cannot have just any value but may only
have a certain specific value
energy levels = n
E = hf
E- definite
amount of
energy
emitted
from atom
hf = light of definite
frequency or
wavelength in
emission spectrum
every element has its own unique arrangement and number of electrons
giving rise to its own unique set of energy transitions thus its own unique
spectrum.
atomic absorption spectrometry
atoms can absorb light.
an absorption spectrum is produced when white light
is passed through a gaseous sample of an element, it
consists of dark lines against a coloured background.
wave nature of an electron.
Louis de Broglie stated
that electrons do not
travel in a fixed path, it
has a wave motion.
Werner Heisenberg.
Heisenbergs
uncertainty principle
states that it is
impossible to measure
the velocity and
position of the electron
at the same time.
an orbital is a region in
space within which there
is a high probability of
finding an electron.
Erwin Schrodinger
Schrodingers equations were solved to give us the shapes of the 4 orbitals S,P,D,F
All S orbitals are
spherical and only
differ in size.
P orbitals are dumbbell
shaped. the three parts
are Px, Py, and Pz