10 9 8 7 6 5 4 3 2 110/28 Flame Tests
1. Make a 2 column by 6 row table in your notebook
2. Label the Columns “Compound” and “Observations”
3. Light your bunsen burner
4. Dip the wooden splint in the liquid
5. Heat it in the flame
6. Record observations for all 5 compounds Na, Li, K, Sr, Cu
WRITE A HYPOTHESIS OR EXPLANATION.
Why do you think what you are observing is happening?
Electromagnetic Spectrum
Long wavelength
Low energy
Low frequency
Short wavelength
High energy
High frequency
Bohr’s Model of the Atom
• e- circle the nucleus in orbits, like planets around the sun
• energy levels are quantized meaning only certain orbits are allowed, the e- can’t be between
• every atom has it’s own unique set of energy levels
BohrModel
• nucleus contains positive protons and neutral (no charge) neutrons
The Quantum Model
• electron “cloud” represents a 95% probability that the e- will be inside
• electrons in orbitals = 3D volume of space where electrons are most likely to be found
Quantum Model
• e- are thought of as both waves and particles (weird right? That’s called wave-particle duality)
• which means you can not know the exact position or speed of an e- (that’s called Heisenberg’s Uncertainty Principle)
Orbitals
Orbitals
Background: The normal electron configuration or arrangement
of atoms is known as the ___________ ________. This is the
most _________ energy state and all e- are in the
__________energy levels possible. When electrons absorb
enough energy they can “jump” to higher energy levels and are
said to be in the _________ ________. However, the excited
state is _______________ and as electrons “relax” back down to
lower energy levels the extra energy is ___________ or given
back off as ____________ light.
Spectroscopy Lab Background
ground statestable
lowest
excited stateunstable
emittedvisible
Each element, depending on its own unique _______________
_________________ (or arrangement), will emit a different
_________________ of colored light that our eyes interpret as
a ___________ color. In order to actually see the individual
colors we need to use a ____________________, which has a
_________ that separates the different wavelengths of light.
Let’s look at the Hydrogen emission spectrum!
Spectroscopy Lab Background
electronconfigurationcombination
singlespectroscope
prism
Emission Spectrum of Hydrogen
If we look at the _______________ _____________ of a single
element we will see only certain unique bright lines. Looking at
this pattern of colored lines is one of many similar analytical
techniques chemists use to identify substances called
________________. Each colored line in an emission spectrum
represents a specific or ________________ electron transition.
electron transition corresponding to a particular energy difference.
Spectroscopy Lab Background
spectrum
quantizedspectroscopy
emission
Electronic Transitions
p+n = 1
n = 2
n = 3
Heat, electricity, or light provides
energy to excite e-
photon
UV, Visible Light, or Infrared emitted as e- drops back to lower energy levels
Only certain colors are emitted because the
transitions are quantized
2324 25
e-
Unstable excited e-
e-
n = 4n = 5e-
e- e-
e-
Spectroscopy Lab Background
If energy levels were not quantized, then theoretically electrons
could make ______ transition. This would result in a full spectrum
of visible color in the emission spectrum or in other words we
would see __________ light emitted by any excited atom as it
relaxes back to the ground state. However, experiments show
that only certain colors are emitted. This is direct evidence that
______________ ____________ _________ exist and
confirmed __________ model of the atom which has electrons in
quantized _____________ around the nucleus.
quantized energy levelsBohr’s
orbit
any
white
ESCHS RECYCLES
IN THE CLASSROOM
EACH CLASSROOM SHOULD HAVE 3 BINS WITH SIGNS!
WE DEPEND ON YOU TO SORT YOUR RECYCLING
ESCHS RECYCLES AND
COMPOSTSIN THE CAFETERIA
Milk & Juice container
Metal, Glass, Plastic, Cartons
LandfillStyrofoam,
Plastic bags, Wrappers
Food Scraps & Paper
e-
e-
n= 1 n=2 n=3 n=4 n= 1 n=2 n=3 n=4
e-
e-
Long wavelength
Low energy
Low frequency
Short wavelength
High energy
High frequency
Absorption vs. Emission Spectra
Absorption vs. Emission Spectra
Absorption vs. Emission Spectra
Stellar Spectra
Stellar Spectra – Which elements?
H400700 600 500650 550 450
400700 600 500650 550 450
400700 600 500650 550 450
He
Ne400700 600 500650 450
Hg
700 600 500650 550 450
Solar
400
550
10 9 8 7 6 5 4 3 2 110/31 Spectroscopy Lab Data
Make three columns in your notebook
MercuryHg
HeliumHe
NeonNe
Science Writing Style: Spectroscopy
accurate / inaccurate / fairly / somewhat / partially / mostly
… the red line at 650 nm
… the green line (486 nm)
… the 410 nm line (purple)… the 580 nm yellow line
matched
observed
shifted
near
in a band from ___ to ___
in a pair / group / set of lines
Science Writing Style: Openers
The experimental results for the Helium emission spectrum were ________ compared to the accepted spectrum because ….Compared to the known spectrum, the experimental results for the Helium emission lines were _________ because…
The experimental Helium spectrum results were ________ in comparison to the accepted emission values because…
accurate / inaccurate / fairly / somewhat / partially / mostly
… the red line at 650 nm
… the green line (486 nm)
… the 410 nm line (purple)… the 580 nm yellow line
matched
observedshifted
near
in a band from ___ to ___
in a pair / group / set of lines