Atomic Model Notes
What is a scientific model and how is it used?
Link 1 Scientific Models http://en.wikipedia.org/wiki/Scientific_modelling

An idea expressed by: writing, drawing, physical, replicas, animations. . .

Can be: used to make predictions

Predictions are: tested by experiments

Can be modified: when predictions are incorrect
 600 2.1 big light

540 2.3 long light
Making A Scientific Model: The Black Box Experiment
In this experiment, you will make a model of the unseen parts inside of a black box. Making a scientific
model involves 4 processes: 1. Forming ideas (the model) about something that is observed. 2. Making
predictions using the model. 3. Testing the predictions with experiments using the model. 4. Correcting
or modifying the model according to information learned in the experiments.
The black box that you will use to help you develop the skill to make a model is made of cardboard. It
has metal rods running through the box. Inside of the box there are objects, which may be similar to
washers. All of the black boxes are set up the same inside. Your lab team will get two black boxes. You
are not allowed to look in the box, but you can tilt it and use your sense of touch and hearing and use a
magnet to develop a model of what you think it looks like inside the box. Draw your model of the inside
of the box.
Next, develop predictions of what you think will happen if you were to pull the rods out of the box.
Test your predictions by using one of the black boxes. Modify your model if your predictions are not
accurate. Test your new model using the second box. Make a final model of the inside of the black box.
Parts of the Atom
Link 2 Parts of the Atom http://www.chem4kids.com/files/atom_structure.html
1. Protons

Found: in the nucleus

Has: a positive charge

Has: a mass of one atomic mass unit

Number of: protons is equal to the atomic number

Number of: protons determines the identity of an element
Link 3 Interactive Periodic Table Link http://www.dayah.com/periodic/
2. Neutrons

Found: in the nucleus

No charge

Mass: equal to one atomic mass unit

The number of: Neutrons = atomic mass - protons

An element may have atoms with different numbers of: neutrons. These are called xs.

C-12, and C-14 are isotopes of carbon.

The average of the isotopes leads to the decimal in the atomic mass
Link 4 Isotopes http://www.chem4kids.com/files/atom_isotopes.html
3. Electrons

Found: outside the nucleus in the electron cloud

Have: a negative charge

Have: such a small mass it is considered zero
Protons
Electron
Nucleus
Neutrons
Electron cloud
Link 5 Proton,
Neutron, and Electron Numbers http://education.jlab.org/qa/pen_number.html

In a neutral atom: # of electrons = # of protons

If the atom has a charge: it is because the atom has gained or lost electrons

Charged atoms are called: ions
 Sodium tends to lose 1 electron so its charge becomes: +1
11 P+
12 N
11 E-
Neutral Sodium
11 P+
12 N
10 E-
Na less 1 Electron
 Oxygen tends to gain 2 electrons so its charge becomes: negative
8 P+
8N
Neutral Oxygen
8 E-
8 P+
8N
10 E-
O plus 2 Electrons
Charges on some of the Atoms
+2
+3
+4
-3

Electrons can move: to higher energy levels when energy is added to the atom

Pathways: electrons take are not just special
-2
-1
Link 6 Parts of the Atomhttp://education.jlab.org/atomtour/index.html
Link 7 The Changing Atomic Model http://www.absorblearning.com/chemistry/demo/units/LR301.html
Spectroscopy

The study of the: spectra of light emitted by elements and compounds

It is used to: identify substances because each element has unique fingerprint of light

The “spectral
fingerprint” is made
of peaks: on a graph
of different
Intensity
+1
wavelengths
400
500
Wavelength (nm)
600
700
0
How Spectroscopy Happens (Why we study this with the atomic model)

Energy: is added to the atom electrons jump out to the excited state

This causes: the electron to jump out to the excited state

Immediately: the electron goes back to the ground state

Resulting in: light being emitted
Link 8 Spectroscopy https://science.howstuffworks.com/laser-analysis2.htm
Unique
Spectra of
Light Emitted
Energy
Excited State
E
E
Ground State
E
E
E
E
Fluorine
E
E
E
E
Figure 1.
Flame Test Lab
When energy is added to atoms the electrons move to a higher energy level. The electrons then move
back releasing the energy. This may be in the form of visible light. Every element gives off a unique color
(wavelength) of light. These colors can be used to identify unknown substances by comparing them to
known elements.
In this lab you will use flame test to observe and record the colors of 7 known elements. On another
lab day you will be given the same elements marked as unknowns. In 7 tiny test tubes place about 1 cm
of solution, which contain the metals: strontium, calcium, copper, lithium, barium, sodium, and potassium.
Use a sheet of paper to mark the names of the elements and place this in front of your test tube rack. To
test the elements dip a nichrome wire into a solution and then place the tip of the wire into a burner
flame. You may have to repeat this several times to get a good observation of the color. Fill a small test
tube about 1/3 full of hydrochloric acid to clean the nichrome wire in between each test by dipping the
wire into the acid and then placing it in the flame until most of the color is gone. After testing all
elements, you may make mixtures and test these to see if you can detect individual colors.
On a following day you will get the 7 elements again marked as unknowns 1-7. You will also get a
mixture containing 2 unknown elements. You can use your observations from day one to help identify
the unknowns.
In the next lab you will exam elements for their spectral graph fingerprint. This can be used in your
analysis section of your lab report.
In your pre-lab make a table containing the following columns: Number of unknown, name of
element(s), detailed color description, and a column to be filled with the color(s) you observed. You will
turn the completed table in as a follow up to the lab. The table should have a figure number and caption
that describes the lab and information in the table.
Spectroscopy Lab
In this lab, you will learn how to use a spectroscope to observe the chemical fingerprint of various
elements and compounds. A spectroscope breaks down light into its different wavelengths (Figure1). In
comparison in the flame test lab you used eyesight alone and were only able to see the colors blended
together.
Figure 1. The diagram shows a bright-line spectrum as seen through our laboratory spectroscope. A
scale on the bottom allows you to measure the wavelength of the lines. The intensity of the lines can be
estimated on a relative 1-10 scale by looking at their brightness.
Use the hand-held spectroscopes and the Loggerpro spectral analysis probes to observe the given
elements and compounds set out in the room. For each sample lights where you do not use Loggerpro
record the type of bulb, the colors you see, their wavelength and their brightness in relationship to each
other on a 1-10 scale. (Add a table like the one below to your pre-lab)
When you use Loggerpro you have to change the y-axis to intensity. You do this by clicking on
Experiment (next to File) and then Change Units/Spectrometer 1/Select Spectrometer Mode and click
Intensity. Aim the fiber optic cable at the light source and the collect button. When you get a good graph
click stop. Change the y units to get tall peaks shown on the graph and then take a screen shot of the
graph including the axis and name the screenshot with the correct element or compound name.
One of these spectral finger print graphs can be used in your analysis section of your flame test lab
report to show what a spectra finger print looks like.
Color of Line
Relative Intensity (10 being the brightest)
Wavelength
Elements and Compounds
Element
•
Any substance that: cannot be broken down further by a chemical reaction
•
Examples: Nihonium
Compound
•
Two or more: elements chemically combined
•
Compounds can be: broken down by chemical means, but not physical
•
Compounds do not: retain the properties of their elements
•
They have set: ratios of their elements
•
Formulas show: H2O
•
Examples:
•
Compounds are: pure substances, mixtures are not
Link 9 Animated Elements and Compounds http://www.chem.purdue.edu/gchelp/atoms/elements.html
Is usually found in the form of…
Matter
Mixtures
Which is usually made of…
Compounds
Elements
Which can be broken down into…
Chemical Bonding
•
The outer shell of electrons are the electrons: electrons involved in bonding. They are known
as valence electrons
1
2
Number of Valence Electrons
3
4
5
6
7
8 (2)
•
Valence electrons are represented: by dot diagrams
Na
Mg
Al
C
Link 10 Dot Diagrams http://hyperphysics.phy-astr.gsu.edu/hbase/pertab/perlewis.html
The Octet Rule:

Atoms are most stable when they have: 8 electrons in their outer shell

They will gain: lose, or share electrons to get to the octet rule.

The exception is if it only has the first energy level, which only needs: 2 electrons to be stable

How many electrons will sodium gain or lose to achieve the octet rule: 1l

How many electrons will barium gain or lose to achieve the octet rule: 2l

How many electrons will chlorine gain or lose to achieve the octet rule: 1g

How many electrons will nitrogen gain or lose to achieve the octet rule: 3g

How many electrons will neon gain or lose to achieve the octet rule: 0
Atomic model test 1 will go up to this point
Ionic Bonds

Atoms:
Link 11 Ionic Bonds https://en.wikipedia.org/wiki/Ionic_bonding
Link 12 Charges and Ionic Bonds Video https://share.vidyard.com/watch/1oiuPx7U9gaRzEY5QprGec

The charged atoms are called: ions

The attraction is between: the opposite charges

Type of bond between: a metal and non-metal
E
E
E
E
E
E
E
E
E
E
E
E
E
Sodium
Chlorine
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
Naming Ionic Compounds
Link 13 Naming Rules http://science.widener.edu/svb/pset/nomen_b.html
Rules for ionic compounds made of two elements; a metal and a nonmetal.
1. Name the: metal first
2. Name the: non-metal second
3. Drop the last syllable of the: non-metal and add “ide”
4. If the metal can form more than one charge (transition elements) indicate the charge with: a
roman numeral

Compound containing Br and Li: Lithium bromide

Compound containing N2 and Ca3: Calcium nitroide

Compound containing Mg and O: Magnesium oxide

Compound containing Fe+3 and S: Iron III sulide
Finding Formulas for Ionic Compounds

The elements in these compounds have: charges because they gain or lose electrons

Examples Na+1, Mg+2, Cl-1, N-3

The overall charge of the compound: has to equal zero

Examples: Sodium nitride (Na+1 N-3): Na3N

Barium fluoride (Ba+2 F-1 ): BaF2
Link 14 Ionic Formula
https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Introductory_Chemistry_(Tro)/05%3A_Molecules_and_Compounds/5.05%3A_
Writing_Formulas_for_Ionic_Compounds
Drawing Dot Diagrams of Ionic Bonds
1st.
Find the: formula of the compound
2nd.
Draw the dot diagram by placing the metal to the: left, nonmetal to the right
3rd.
Electrons that transfer are shown as: X’s
4th.
If there is more than one atom in the formula: stack the atoms
5th.
Include the: charge of each atom
Example: Sodium chloride
+1
Na
X
-1
Example: Magnesium fluoride (you may have to copy paste parts)
Mg
+2
X
-1
X
-1
F
F
Covalent Bonds
Link 15 Scroll to Covalent Bonds http://www.visionlearning.com/library/module_viewer.php?mid=55

Atoms: share electrons to become more stable by fulfilling the octet rule

Atoms share: pairs of electrons

Covalent bonds occur between: nonmetals

Compounds are: referred to as molecules
Link 16 Covalent Bonds https://www.thoughtco.com/definition-of-covalent-bond-604414
E
E
E
E
F
E
E
E
E
E
E
E
E
E
E
F
E
E
C
E
E
E
E
F
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
F
E
E
E
E
Naming Covalent Compounds
Link 17 Naming Covalent Compounds https://cpanhd.sitehost.iu.edu/C101webnotes/chemicalnomenclature/bimolcmpds.html

Name the element furthest: left (first except hydrogen) (in same family; name the lower first).

Drop the last syllable of the 2nd element: and add “ide”

Add prefixes to the element to indicate: the numbers in the formula

1 is: mono, 2 is di, 3 is tri, 4 is tetra, 5 is penta, 6 is hexa

Never use: mono on the first element

Examples: CO2: Carbon Dioxide CO: Carbon monoxide N2H6: Dinitrogen Hexahydride
Finding the Formulas for Covalent Compounds

Look at: the prefixes

Silicon tetrachloride SiCl4
Covalent Dot Diagrams
1st.
Find the: formula of the compound
2nd.
Place the element symbols: symmetrically around a center atom
3rd.
Calculate the number of bonds: for each atom using the octet rule
4th.
Complete the octet rule: around each atom
Sulfur Dichloride has 20 dots because: the number of valence electrons for two chlorines and one sulfur
S
Covalent Bonding Lab
Covalent bonds occur when atoms share electrons to become more stable by fulfilling the Octet Rule.
The smallest group of covalently bonded atoms for a compound is referred to as a molecule. For example
H2O is the molecule that makes up water. In this lab you will make models of molecules of various
covalent compounds.
When you get your molecular model kit you must first use your periodic chart and what you know
about the octet rule to decide what color ball will represent each of the following elements: carbon,
hydrogen (you will need a lot), oxygen, chlorine, bromine, and nitrogen. When you have decided you will
then draw the dot diagram for carbon tetrahydride (methane). When you have your dot diagram correct
you can build your model of the molecule. When you have that model correct you will then draw the dot
diagram for dicarbon hexahydride. When you have your dot diagram correct you can build your model of
the molecule. Continue the same process for: dihydrogen monoxide, dicarbon tetrahydride, Cl2, O2,
nitrogen trihydride (ammonia gas), and carbon dioxide.
Ionic or Covalent Compound Lab
Ionic or covalent compounds often differ in the following ways: Ionic compounds may have harder
crystals than covalent compounds. They may dissolve better in water. Ionic compounds when dissolved
in solution may conduct electricity better and they may higher melting points than covalent compounds.
In this lab you will get four compounds and you will rank them from 0-5 for each category underlined
above with the goal of determining if the compounds are ionic or covalent. In your pre-lab you should
make a data table to keep track of your rankings of the four compounds (A-D) for each category.
Do not touch the chemicals with your fingers. If a chemical come in contact with your wash it off
immediately. Use the microspactula or scoopula to move the chemicals around.
Use a microspatula to try and crush a few crystals of each on the aluminum tray provided. Place a few
crystals of each on a microscope slide and set this on a hot plate set on low to check for relative melting
points. If it turns brown and smokes that is a chemical reaction not melting. You should stop if that
happens.
Place a few crystals of one of the compounds in a 100 ml beaker containing 20 ml of water to see if it
dissolves. If it does try some more to test to see how soluble it is. Next test the solution with the probes
of a voltmeter to see how well it conducts electricity. Repeat the tests for each compound. Use a
preponderance of evidence to determine if the compound was ionic or covalent.
Formation of the Atom and the Big Bang
Just before the Big Bang

The big bang occurred about 14 billion years ago

The "inflationary universe" model assumes that before the big bang the universe had an extremely
concentrated, unstable form of energy, but no matter
The Big Bang
Link 18 The Big Bang Theory http://science.nasa.gov/astrophysics/focus-areas/what-powered-the-big-bang/

Energy changed into matter during the big bang

One second after the big bang protons, neutrons, and electrons had formed

By three minutes after the big bang hydrogen the first element had formed
Less than a billion years after the big bang

Stars form as hydrogen comes together by the force of gravity

In stars hydrogen forms helium through the nuclear reaction fusion which produces the light and heat
given off by stars

Billions of years later, as stars go super nova the tremendous pressure and heat caused the helium to fuse
together to form all of the other elements in the universe

These elements eventually came together by the force of gravity to form the planets
Elements Fused Together
Evidence that the Big Bang Occurred

The universe is still expanding today as a result of the big bang

There is background radiation every where in the universe left over from the big bang
What we can determine by looking at the stars
Link 19 Examining Spectral Fingerprints
https://imagine.gsfc.nasa.gov/features/yba/M31_velocity/spectrum/spectra_info.html

The primary cause of star color is the temperature of the stars

Cooler stars radiate most of their energy in the red and infrared region of the electromagnetic spectrum
and thus appear red

Hotter stars emit in the yellow part of the spectrum

The hottest stars emit mostly at blue and ultra-violet wavelengths, making them appear blue or white
Which stars are the coolest? Hottest?
Why is our sun yellow?
Using Spectral Analysis to Find Composition of Stars
Link 20 Composition of the Sun http://www.space.com/17170-what-is-the-sun-made-of.html

Scientists break light from stars into its spectral fingerprint to determine the composition of the
elements in the star
Spectral Fingerprint of the Sun
Our Solar System
Link 21 Solar System Facts http://earthsky.org/space/ten-things-you-may-not-know-about-the-solar-system

The solar system and earth formed about 4.5 billion years ago

It formed as elements and compounds from previous supernovas came back together by the force
of gravity

Earth is the right distance for life because water can exist in the 3 phases; solid, liquid, and gas
making the earth’s water cycle possible