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