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Embed code for: The Atom Unit
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Mixtures Notes/Bolts Activity: Slides 6-16,
Mixture Separation Lab: Slides 17-33,
Atomic Timeline Foldable: Slides 39-58,
Bohr Model Foldable: Slides 62-93
Isotope Notes: Slides 102-114
Share a memory.
Agenda/Objectives – 9/27/16
Mock Electron Tentative Schedule
Notes on Elements, Compounds, and Mixtures
Nuts and Bolts Activity
Pre-Lab on Separation of Mixtures
Be able to differentiate between elements, compounds, and mixtures
Apply understanding of mixtures to real life
We must first think about how the idea of the Atom surfaced.
How did scientists come up with the idea of the atom?
How Can We Differentiate?
It began with the element – the idea that there were substances that could not be broken down any further.
“How can we get the purest substance?”
Everything is made up of matter.
“What is the difference between atoms and matter”
Elements and Compounds
The purest substances were known as elements.
Elements are substances that cannot be chemically broken down into simpler substances and are the primary constituents of matter.
Ex: Oxygen, Nitrogen, Copper,
Scientists also knew that elements could chemically combine to form compounds.
Compounds are substances made up of elements that are chemically combined.
Ex: Water, Sodium chloride (salt), Ethylene glycol,
When referencing elements and compounds, the term pure is often used.
Purity describes a substance whose matter consists of only one element or compound (remember that compounds are elements that are chemically bound together!).
But we know that most things aren’t pure, they are mixtures.
Mixtures are substances made up of elements and/or compounds that are physically combined.
Ex: Salt Water, Sand,
There are two types of mixtures: homogeneous and heterogeneous
Homogenous describes a mixture that appears to be evenly mixed in the same concentration.
Ex: Milk, Orange Juice (no pulp),
Heterogeneous describes a mixture that is not evenly mixed in the same concentration.
Ex: Mixed Nuts, Orange Juice (with pulp),
Mixtures vs Compounds vs Elements (Nuts and Bolts)
Label each picture according to what you think it represents (compound or element)
Each group will be given a bag, which may contain nuts or bolts or both.
Using your understanding of mixtures/compounds/elements, associate each bag with what each bag might represent.
Mixtures vs Compounds vs Elements (Nuts and Bolts) Make-Up Activity
If you are absent from class, this is the make-up activity to be completed on your own time.
Label each picture on the following slide as a compound, element, or mixture of compound and/or element.
Answer questions on the slide following the images.
Questions to Ponder:
Can mixtures be a combination of compounds and elements?
Are mixtures and compounds mutually exclusive (can there be mixtures of compounds)?
Venn Diagram Activity
Using your knowledge so far (definitions and examples), create a Venn Diagram showcasing the difference between an Element, Compound, and Mixture.
Cannot be broken down
Oxygen, Nitrogen, etc.
Made up of elements chemically combined
Can be broken down through chemical means
Water (H2O), Carbon dioxide (CO2), etc
Made up of elements/atoms
- Does not have to have a specific ratio of elements
- Made up of combined elements
Can be homogeneous or heterogeneous
Made up of elements physically combined
Salt water, orange juice
Do you think a Venn diagram is an appropriate way to display the differences between Elements, Compounds, and Mixtures?
Mixture Separation Lab
To apply an understanding of physical changes to separation of mixtures (homogeneous and heterogeneous).
Compared to compounds, mixtures can be made up of various amounts of elements and/or compounds. While compounds have to be combined in whole number ratios (ex: two hydrogen atoms for every one oxygen atom [H2O]), mixtures have no perfect “formula” in which they are to be made.
For example, there is no exact recipe for lemonade, as people can adjust the amount of sugar, water, and lemon juice to their liking. Additionally, because mixtures are a physical combination of elements/compounds, the constituents of the mixtures can just as well be physically separated.
In this activity, you will have a mixture of various compounds, which include sand, table salt, sugar, iron fillings, and extra virgin olive oil. Your goal is to separate these compounds into their individual constituents.
400 mL Beaker
Double boiler set-up
Rubbing alcohol (91%)
What is your favorite day of the week?
Agenda/Objectives – 9/29/16
Atomic Classroom Activity
Pre-Lab/Lab on Separation of Mixtures
Understand the quantum model of the atom
Remove the iron filings with a magnet. You are left with sand, salt, and sugar.
Add water to the mixture (what does the water do?).
Filter the mixture using filter paper, a funnel, and a beaker.
You are left with sand, salt, and water (how do you get rid of the water?).
Evaporate the water using the Bunsen burner. Add alcohol to the mixture (salt and sugar)(what does the alcohol do?).
Filter the mixture again using filter paper, a funnel, and a beaker.
You are left with sugar dissolved in alcohol.
You are left with sugar dissolved in alcohol
Evaporate the alcohol.
Type of Substance Removed
Type of Substance Remaining
Sand, Salt, Sugar, Iron
Sand, Salt, Sugar
Completing the Lab:
Make sure the substances are all separated and collected in individual test tubes.
Bellwork – 10/5/16
What is something you are struggling with?
Bellwork – 10/7/16
What is your favorite genre of music?
Agenda – 10/7/16
Atomic Theory Timeline Foldable
Atomic Theory Timeline Notes
The Atomic Timeline
1. Apply knowledge of the atom’s history to understanding of the atom.
The Atomic Timeline Foldable
Fold the sheet in half and cut the four lines (red lines) to create five flaps.
Label the flaps on the outside with the names of the scientists that contributed to the discovery of the models of the atom (there are only five flaps, so there should only be five scientists)
J. J. Thomson
On the other side of the flaps, draw a diagram of the model of the atom proposed by the scientists.
Opposite of the drawings will be the information regarding the discovery made by the scientists.
On the back of your foldable, compare and contrast the different models of the atom throughout history.
Comparing the Models
Date: 460 BCE
Ideas: All matter is composed of extremely small particles called atoms.
Quote: “We can only break things over and over so many times. When does it end?”
Date: 330 BCE
Ideas: All matter is composed of different elements (fire, earth, air, water).
Quote: “Long ago, the four elements lived together in harmony. Then, everything changed when the atomic theory was proposed.”
Name: John Dalton
Ideas: All elements are composed of atoms. Atoms cannot be subdivided
Quote: “The daft Aristotle reversed the progress of Chemistry by some twenty centuries.”
John Dalton (cont.)
Name: J. J. Thomson
Ideas: Atoms are composed of corpuscles (electrons) distributed in a sea of positive charge.
Quote: “I like Jell-O made with real fruit inside.”
How did Thomson propose the idea of a “positive sea” if his CRT experiment only observed negative particles?
J. J. Thomson (cont.)
Experiment: Interacted with electric discharge of cathode ray tubes to determine the existence of negative particles.
Model: Plum Pudding Model
Name: Ernest Rutherford
Ideas: The protons are located at the center of the atom. The electrons orbit the protons.
Quote: “My teeth gleaming like I’m chewing on gold foil.”
Ernest Rutherford (cont.)
Experiment: Fired positive alpha particles at a thin sheet of gold foil. Discovered that alpha particles would sometimes be deflected.
What would firing positive particles at a sheet of gold foil do?
the plum pudding model vs. the Rutherford model
Name: Niels Bohr
Ideas: The electrons must orbit the protons in specific energy levels. Electrons can jump between orbitals by absorbing energy.
Quote: “For a good clean feeling no matter what.”
Niels Bohr (cont.)
the Rutherford model vs. the Bohr Model
Name: Various Scientists
Date: 1927 (Fifth Solvay Conference)
Ideas: Quantum mechanics suggest that we can never know exactly where electrons are located in the atom. We can make predictions of what orbitals electrons might be located in.
Quote: “We hold these truths to be self-evident, that all atoms are created equally.”
Various Scientists (cont.)
the Dalton Model vs. the Quantum Model
Bellwork – 10/11/16
What frustrates you?
Agenda – 10/11/16
Analysis of the atom/Bohr Model
Differentiation between neutral atoms, ions, and isotopes
Parent teacher conferences are Thursday 10/13/16
The Bohr Model
1. Apply new information about the atom to prior understanding of subatomic particles
The Bohr Model (Foldable)
Fold your paper into 4 long panels.
Fold the two end panels together so that you have two flaps that can open.
Draw a line in the middle of the front flaps of your book. Cut the line on the front flaps so you have four flaps.
Label the front of the four different panels: the atom, proton, neutron, electron
Label the outer panels/flaps: what I know. Label the inner panels: what I learned.
What I know
What I learned.
Prior Knowledge Exploration:
In the “what I know” sections for the atom, proton, neutron, and electron, write down one or two things that you already know about the concept.
Draw a picture of what you think an atom looks like on the “what I know” panel of the atom.
On the back side of your foldable, label the entire space “The Bohr Model.”
The Bohr Model was introduced by Niels Bohr and Ernest Rutherford to depict the subatomic particles of the atom.
It is one of the most useful models of the atom, providing sufficient and accurate information about the atom in a simplistic illustration.
Different elements on the periodic table have different atomic structures.
This means that the different elements have different number of protons, neutrons, electrons.
What the Bohr Model of an atom looks like
What you might have drawn prior to this class (or possibly Physical Science)
Compare the two models. The left one is a carbon atom, the right one is a lithium atom.
Bohr Models can be depicted in many ways. The most important aspects of the Bohr Model are:
Nucleus is located in the center
Protons and Neutrons are labeled in the nucleus
Electrons orbit around the nucleus in orbitals*
*The electrons must be placed in the orbitals in a specific manner.
The Subatomic Particles:
Proton – the positive subatomic particle of the atom, located in the nucleus.
Number of protons – determine the identity of the atom (what element the atom represents). All atoms have some number of protons. Also determines the mass of the element.
Reading the Periodic Table:
The Bohr Model (Periodic Table)
Neutron – the neutral subatomic particle of the atom, located in the nucleus.
Number of neutrons – accounts for part of the mass of the atom (along with the number of protons).
Atomic Mass – The atomic mass of an atom/element can be determined by finding the sum of the number of protons and the number of neutrons.
Atomic Number + Number of Neutrons = Atomic Mass
Scientists needed a way to quantify the mass of very small particles, so they developed a standard of mass using elements. They called this the atomic mass unit (amu or u).
They discovered that an atom’s mass is mostly made up of the proton and neutron. Through calculations they found that:
The mass of Proton is equal to 1.007 amu (u)
The mass of Neutron is equal to 1.008 amu (u)
For the sake of simplicity, we will use a value of 1 atomic mass unit for both the mass of protons and neutrons.
Atomic Mass – Atomic Number = Number of Neutrons
If an atom has 5 protons and 7 neutrons, what is its mass?
How many neutrons does the average carbon atom have?
Determining the number of protons, neutrons, electrons, and the atomic mass:
Electron – the negative subatomic particle of the atom that orbits the nucleus in the electron cloud.
Role of electrons – electrons play an important part in chemical bonding and formation of ions.
How can you figure out the number of electrons in a neutral atom if you are given the number of protons? (Think about the charge of the particles and the atom)
Number of electrons – determined by the number of protons (only for neutral atoms).
The Bohr Model (The Periodic Table)
Complete the top half of the information side on your periodic table.
Identify the element given its Bohr Model:
What is the mass of this element/atom?
Atoms, Ions, and Isotopes Foldable
Fold the sheet of paper into thirds.
Open it back up and cut off one end of the pieces. Staple/tape it to the back or inside center of your foldable.
Tape or Staple here
Divide the long foldable into thirds.
Label the front of the foldable as it looks below.
On the following page, complete the inside of the foldable with the following information.
How to find number of protons, neutrons, electrons
Task 5 (cont.):
Complete the inside of the foldable with the following information.
Draw a Bohr Model of a neutral atom
Give five examples of a neutral atom
Draw a Bohr Model of an isotope
Give five examples of an isotope
Draw a Bohr Model of an ion
Give five examples of an ion
Bellwork – 10/19/16
What is your favorite restaurant?
Agenda – 10/19/16
Isotopes Virtual Lab
Atomic Campaign Preparation
Atoms, Ions, and Isotopes
Can the atom of a specific element gain or lose protons? Why or why not?
What would happen if an atom gains a proton?
We know that atoms cannot gain/lose protons without changing its identity.
Can the atom of a specific element gain or lose neutrons? Why or why not?
It turns out that atoms cannot gain or lose neutrons, aside from radioactive processes.
Gaining or losing neutrons would require a lot of energy!
However, different atoms of an element can exist with various number of neutrons. Atoms of the same element with differing numbers of neutrons are called isotopes.
Many of you may be familiar with the term “isotope,” but were not aware that it is associated with atoms.
Compare these images of atoms.
First, look at how many protons each atom has. (What element is this?)
Then look at how many neutrons each atom has.
What does the number after the elemental name represent? (What does the number 12 after carbon-12 represent?)
To write the name of an isotope:
Write the elemental name
Add a dash and write the mass number (total number of protons and neutrons)
Examples: Carbon-14, Nitrogen-15, Sulfur-33
Naming the isotopes (what element is this?):
The importance of isotopes:
Isotopes are responsible for the atomic mass of elements.
Review: compare the atomic masses of your periodic table with the large one in the room. What differences are there?
The mass (in decimal form) on the Periodic Table represents the AVERAGE of all isotopes.
What is an average?
Math review: The average is the mean number calculated by dividing the sum of a set of numbers by the total number of numbers in the set.
Practice with averaging numbers (cont.):
What is the average test score for the class?
100+100+100+98+100+100+100+100 = 798
798/8 = 99.75
What is the average number of arms that a human would have on earth? Explain how you predicted that number.
Explain why the average atomic mass (on a regular periodic table) is extremely close to a whole number.
All atoms are isotopes, not just atoms that have different numbers of neutrons.
Bellwork – 10/21/16
What is your favorite letter?
Agenda – 10/21/16
Post-Lab Discussion for Isotopes
Things you will need:
For Neutral Atoms (atoms of elements with no charge)
Protons: Atomic Number
Neutrons: Mass Number – Atomic Number
Electrons: Same as Number of Protons
For Isotopes (atoms with varying number of neutrons)
(Do isotopes have a charge?)
All Atoms are Isotopes.
The method for determining the number of subatomic particles for an atom and an isotope is the same.
Remember that isotopes are written with the elemental name followed by the atomic mass of the isotope.
Isotopes of Carbon
Determine the number of protons, neutrons, electrons, and the atomic mass:
Importance of Isotopes
Predict the most common isotope of Phosphorous. Explain your answer.
Predict two common isotopes of Iron and their abundancies.
What would happen to an atom if it were to gain an electron? (What would the charge of the atom be?)
Can the atom of a specific element gain or lose electrons? Why or why not?
Atoms that gain or lose electrons are called ions.
Name/Symbol of Ions:
Ions can be written as the elemental symbol with a number following and a plus (+) or a minus (-) sign, depending on whether an atom has gained or lost an electron.
Ions that are positive have lost electrons
Ions that are negative have gained electrons
Certain ions will always gain or lose a specific amount of electrons. Copy down these numbers on your periodic table.
For the sake of this class, we will only be looking at main-group elements
Examples of ions:
Na+, Cl-, O2-
How come some ions gain or lose a specific number of electrons?
Main-group gain or lose electrons as a result of the octet rule. The octet rule states that main-group elements want to have EIGHT electrons in their outer shell (also known as the valence shell).
Bohr Models of Atoms, Ions, and Isotopes
Compare the number of electrons in different ions. What similarities are there?
You might have noticed that many ions of the main-group elements either have 18 or 10 electrons total
Why is that?
The outer shell of the atom is also called the valence shell, with the electrons being called valence electrons.
The Bohr Model tells us that electrons of atoms are located in specific shells (rings) around the nucleus, and each shell can only hold a specific number of electrons.
Draw a Bohr Model of a neutral Nitrogen atom with the electrons depicted in their appropriate shells. (What is located in the nucleus?)
What is located in the nucleus? How many of each particle will there be?
Remember the three criteria required for a proper Bohr Model
Draw a Bohr Model of a neutral Magnesium atom with the electrons depicted in their appropriate shells.
Draw a Bohr Model of a neutral Sodium atom with the electrons depicted in their appropriate shells.
Draw a Bohr Model of a neutral Aluminum atom with the electrons depicted in their appropriate shells.
Draw a Bohr Model of a neutral Bromine atom with the electrons depicted in their appropriate shells.
Each table will be given a column of elements. Pick one from the column and draw the Bohr Model for that element.
Ex: Column 17 – Chlorine
Draw a Bohr Model of a neutral Sodium-24 atom with the electrons depicted in their appropriate shells.
Draw a Bohr Model of a neutral Aluminum-36 atom with the electrons depicted in their appropriate shells.
Draw a Bohr Model of a neutral with the electrons depicted in their appropriate shells.
Further Thinking/Additional Practice:
Draw a Bohr Model of Fluorine Ion (F-).
What does the minus symbol (–) on the F signify?
We know that atoms can gain/lose electrons by forming ions.
We know that atoms can exist as isotopes with different numbers of neutrons.
Can an atom be both an isotope and an ion?
Draw a Bohr Model of Aluminum-26 3+.
Complete the Venn Diagram on the following slide:
Things to keep in mind:
Think about how subatomic particles are calculated for each type of atom
Think about the structure of each type of atom
All Atoms Are Isotopes
Equal number of protons and electrons
Overall neutral charge
Mass of neutral atoms/isotopes vary
Subatomic particles are not lost, they exist as is
Atoms that have gained or lost electrons depending on the element
Atom can be positive or negative
Masses of ions of the same element are the equal
Subatomic particles are lost and gained
Isotopes can also be Ions
Same number of protons
Bellwork – 10/25/16
What is your favorite type of water?
Agenda – 10/25/16
In previous slides, I spoke about not being able to change the number of protons/neutrons…
Well, it’s not particularly true.
It is possible for atoms to change how many protons/neutrons they have, but it takes a lot of energy. Just remember that changing the number of protons changes the identity of the element.
Since we will be talking about isotopes again, let’s review how specific isotopes of elements are written out as well as learn a new way to indicate elemental isotopes.
Naming an Isotope:
(Elemental name)-(mass number)
Ex. Lithium-12, Chlorine-37, Aluminum-38
Naming an Isotope using Isotope Notation:
Write the isotope notation for:
Carbon-14, Potassium-40, Oxygen-18, Strontium-84
Changes that occur within the nucleus are called nuclear reactions.
These reactions can occur naturally and unnaturally.
Unnatural reactions are artificial/induced, and can be catalyzed by bombarding atoms of elements with high energy particles.
Naturally occurring reactions are common and typically occur in the form of nuclear decay.
Nuclear Decay (Radioactive Decay) is when the nucleus breaks down and emits radiation in the form of particles, photons, or both.
Radioactivity describes all forms of nuclear reactions
Types of Nuclear Decay
In Alpha Decay, an atom loses an alpha particle as a result of instability.
An Alpha Particle is also known as a helium nuclei. It is composed of two protons and two neutrons.
Alpha decay is usually restricited to heavier elements (Thorium, Uranium, etc.)
When the atom loses an alpha particle, what happens to the number of protons and neutrons?
The number of protons and neutrons is each lowered by two and the mass is lowered by a total of four!
In a balanced nuclear equation for alpha decay, the sum of the mass numbers (superscripts) on the right must be equal to the numbers on the left
The same is true for the atomic numbers (subscripts)
Practice Alpha Decay:
Pb He + Hg
Rn He + Po
More Practice Alpha Decay:
The element radium was discovered by Marie and Pierre Curie in 1898. One of the isotopes of Radium, Radium-226, decays by alpha emission.What is the resulting element?
Bellwork – 10/27/16
What is the spookiest experience you’ve ever had?
Agenda – 10/27/16
Nuclear Decay + Half-Life Notes
There are three types of Beta Decay:
In Electron Emission, an electron is ejected from the nucleus.
The charge of the atom increases by one positive (+)
The mass number does not change!
Beta Decay – Electron Emission
But wait, Mr. Chu!
Why does losing an electron cause the atom to change its identity?
Well, you see...
In electron emission, the electron that is emitted is not an electron that is orbiting the atom; it is actually being emitted from the neutron, causing the neutron to turn into a proton!
Again, we see how the neutron of an atom undergoes electron emission changes.
When representing subatomic particles, the red numbers represent the mass and the blue numbers represent the charge.
Practice Beta Decay – Electron Emission:
Na e + Mg
Se e + Br
Often times, when thinking about Nuclear Decay/Reactions, there is fear in the idea of radioactivity.
Radiation is emitted in the form of tiny subatomic particles and waves that have a high energy level, and it is true that these particles can be damaging.
Of the three types of nuclear decay, which do you think is the most damaging and why? (Think about the size of the particles emitted)
Rate of Nuclear Decay
Now that we understand that nuclear reactions occur (naturally), let’s talk about the rate at which radioactive elements undergo nuclear reactions.
Do all unstable atoms decay at the same rate?
Of course not! This world is not that perfect. Nuclear Reactions are spontaneous.
Scientists calculate the rate of radioactive decay of different isotopes by measuring the time it takes for half of a sample of radioactive atoms to decay.
This is called the Half-Life.
Three important notes about half-life:
Each radioactive isotope has its own half-life
More stable atoms decay slower/have longer half-lives
The amount of time it takes for half the amount of a radioactive isotope to decay is the same regardless of how many atoms you start with.
A = A0
A = A0
You can use the following equation to calculate how much of an isotope will remain after a given number of half-lives
“A0” is the initial amount. “A” is the final amount.
The variable “n” represents the number of half-lives. It can also be calculated by taking total amount of time divided by the time per half-life.
You have 400 milligrams (mg) of a radioisotope with a half-life of 5 minutes. After 30 minutes, how many half-lives will the radioisotope undergo? How much of the original isotope will be left after 30 minutes?
30/5 = 6 (half-lives) 400/(26) = 6.25 milligrams
How much of a 3.5 milligram sample of Nickel-63 will remain after 368 years if the half-life of the radioisotope is 92 years? (How many half-lives are in 368 years?)
368/92 = 4 (half-lives) 3.5/(24) = 0.219 milligrams
Half-Life (Reverse Sweep)
A particular isotope has a half-life of 5 days. A particular sample is known to have contained one million atoms when it was put together, but is now observed to have only about 125,000. How long ago was the sample assembled?
# of Half-Lives
# of Atoms
Half-Life (M&M Lab)
Apply understanding of half-life to the spontaneous rate at which M&M’s change (decay).
Become more familiar with half-life calculations.
Keep in mind:
Do not consume M&Ms until all of the M&Ms have been flipped and removed from the containers.
Clean up after yourselves!
M&Ms are good to use if they have visible lettering on them
You don’t need exactly 100; 90-110 is fine.
# of M&Ms unchanged
# of M&Ms Unchanged
# of M&Ms Changed
Half-Life (M&M Lab) Make-Up
Graph the data on your work sheet.
Your Y-Axis should be the # of Half-Lives
Your X-Axis should be the # of M&Ms Unchanged
The information required to answer questions on the Conclusion section can be found in the Background section of your Lab Sheet.
You can have mixtures of elements and/or compounds.
goes electron emission changes.
Often times, when thinking about Nuclear Decay/Reactions,