Intro to Isotopes PhET Lab
by Chris Bires
Introduction: Breath in…Breath out.
Again! When you inhale air, you
are not just inhaling a mixture of oxygen, nitrogen, and trace gasses, but a
mixture of different oxygen atoms and different nitrogen atoms. It turns out that all oxygen atoms have the
same number of protons, but some may have different numbers of neutrons. These different-but-still-oxygen atoms are
called isotopes. Some atoms have just
two isotopes; some have dozens!
Some handy vocabulary for you to define:
Proton: A stable subatomic particle occurring in all atom's nucleus. Have a positive electric charge.
Neutron:
A subatomic particle with no electric charge. Present in all atom's nucleus and has about the same mass as a proton.
Isotope: An element that contains a different number of protons then neutrons.
Atomic
Mass:
Is about equivalent to the number of protons and neutrons.
Radioactive:
Emitting or relating to the emiision of ionizing radiation or particles.
Natural Abundance: the abundance isotopes of a chemical element naturally found on a planet.
Procedure: PhETàPlay with the Sims à Chemistry à Isotopes and Atomic Mass
·
Take some time
and play with the simulation. Imagine
you are manipulating atoms! EXCITING!
·
Be sure to
activate
and
1. How do the number of protons change
as atomic number increase by one?
As the atomic number goes up by one, the number of protons goes up by one.
2. How does the mass of the atoms change
as atomic number increases by one?
As the mass of the atom goes up, the atomic number is also increasing.
3. What effect does adding a neutron
have on the atom’s identity?
When you add 1 neutron to the atom, the mass number, atomic mass (amu), and the symbol number also go up. The atom also becomes unstable.
4. What effect does adding a neutron
have on the atom’s mass?
When you add 1 neutron, the mass number disappears. For example, in Helium the mass starts at 4.00260 and after you add 1 neutron, the mass goes to "---"
5. Draw the nucleus of the most abundant isotope of each of the following atoms in the
boxes below. Be sure to count and label
the protons and neutrons.
6. Also show the full atomic symbol.
Hydrogen has been done for you.
Hydrogen: H Carbon:
C Oxygen: O Neon: Ne
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Complete
the chart below. In some cases, you will
need to work backwards to fill out missing information.
Isotope Name
|
Atomic Number
|
# of Protons
|
# of Neutrons
|
Mass Number
|
Stable?
(Y/N)
|
Ratio
of neutrons to protons
|
Hydrogen-2
|
1
|
1
|
1
|
2
|
Yes
|
1-1
|
Helium-3
|
2
|
2
|
1
|
3
|
yes
|
1-2
|
Helium- 5
|
2
|
2
|
3
|
5
|
no
|
3-2
|
Lithium-6
|
3
|
3
|
3
|
6
|
yes
|
1-1
|
Lithium - 7
|
3
|
3
|
4
|
7
|
no
|
4-3
|
Oxygen-16
|
8
|
8
|
8
|
16
|
yes
|
1-1
|
Oxygen-17
|
8
|
8
|
9
|
17
|
yes
|
9-8
|
Oxygen-18
|
8
|
8
|
10
|
18
|
yes
|
5-4
|
Neon-20
|
10
|
10
|
10
|
20
|
yes
|
1-1
|
Neon-23
|
10
|
10
|
13
|
23
|
no
|
13-10
|
Analysis Questions You may need to use the internet to define
some terms.
1. Water is H2O. How many isotopes of hydrogen exist in
nature? (even unstable ones)
_____7_____
2. Use the internet to search for “heavy
water.” What is this stuff?
It used to be called deuterium oxide or 2h20. It's a form of water that uses hydrogen isotope deuterium instead of the ordinary protium.
It used to be called deuterium oxide or 2h20. It's a form of water that uses hydrogen isotope deuterium instead of the ordinary protium.
3. How does it behave, compared to
ordinary water?
Heavy water boils at a little bit lower temperature then ordinary water. Heavy water is also 11% more dense then normal water.
Heavy water boils at a little bit lower temperature then ordinary water. Heavy water is also 11% more dense then normal water.
4. Does heavy water’s ice float or sink
in ordinary water? Why?
No, because heavy water is more dense then original water, therefore it will sink.
No, because heavy water is more dense then original water, therefore it will sink.
5. Observe the atoms you determined to
be unstable. What can you conclude about
the ratio of neutrons to protons and a nucleus’ stability?
The ratio of neutrons to protons in an unstable atom, was that the neutrons outnumbered the protons, so the ratio was high to low.
The ratio of neutrons to protons in an unstable atom, was that the neutrons outnumbered the protons, so the ratio was high to low.
6. What makes Carbon-14
so useful in “carbon dating” or “radio
dating”?'
Carbon-14 helps show how old something is. Scientists use it to tell how old a fossil or event he earth is. A neutron decays and turns into a proton and electron .
Carbon-14 helps show how old something is. Scientists use it to tell how old a fossil or event he earth is. A neutron decays and turns into a proton and electron .
7. Could a stable isotope of carbon be
used in the same way? Why or why not?
No, because the neutron wouldn't decay and leave the extra energy for the proton and neutron.
No, because the neutron wouldn't decay and leave the extra energy for the proton and neutron.
Molecule Madness
Intended for Fourth Gradersby Taylor Molitor
To complete this activity, please go to http://phet.colorado.edu/en/simulation/build-a-molecule and click the Run Now button, to start the simulation.
Part 1: Make Molecules
For the first part, you are going to be using different "kits" (located at the bottom of the simulation) to create the molecules in your collection that are shown on the sidebar to the right. Answer the following questions as you work along with the simulation. Before we start making molecules, let's refresh ourselves on the elements we will be using.
Element
|
# of Protons
|
# of Electrons
|
# of Neutrons
|
Charge of Atom
|
Hydrogen
|
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Oxygen
|
||||
Nitrogen
|
||||
Carbon
|
Collection 1:
1. What two elements is Water made of? __________________
2. How many of each element makes up water? ________________________
3. Draw what a water molecule looks like:
4. What two elements is Oxygen made of? __________________
5. How many of each element makes up oxygen? ________________________
6. Draw what a oxygen molecule looks like:
7. What two elements is Hydrogen made of? __________________
8. How many of each element makes up hydrogen? ________________________
9. Draw what a hydrogen molecule looks like:
10. What two elements is Carbon Dioxide made of? __________________
11. How many of each element makes up carbon dioxide? ________________________
12. Draw what a carbon dioxide molecule looks like:
13. What two elements is Nitrogen made of? __________________
14. How many of each element makes up nitrogen? ________________________
15. Draw what a nitrogen molecule looks like:
Part 2: Larger Molecules
For the second part, click on the Larger Molecules tab at the top of the screen. This section is kind of like the first section, but instead you get to build your own molecules. In this section, you are to create molecules of at least three different elements and you can not use ones you already made. You must make one from each kit. Look at my example, if you get stuck. First let's review the elements we haven't covered yet.
Element
|
# of Protons
|
# of Electrons
|
# of Neutrons
|
Charge of Atom
|
Chlorine
|
||||
Fluorine
|
||||
Boron
|
||||
Silicon
|
||||
Sulphur
|
||||
Phosphorus
|
||||
Bromine
|
Example:
1. What molecule did you make? _____Water_______
2. What elements make up this molecule? ____2 Hydrogen and 1 oxygen____
3. Draw your molecule.
Kit 1:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 2:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 3:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 4:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 5:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 6:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
Kit 7:
1. What molecule did you make? ________________
2. What elements make up this molecule? ____________________
3. Draw your molecule.
This lesson will meet the following standards:
B.4.1 Use encyclopedias, source books, texts, computers, teachers, parents, other adults, journals, popular press, and various other sources, to help answer science-related questions and plan investigations
Students will be using PhET simulation to answer questions about molecules and to build 3D molecules.
C.4.6 Communicate the results of their investigations in ways their audiences will understand by using charts, graphs, drawings, written descriptions, and various other means, to display their answers
Students will be taking what they learn and put their answers into graphs or writing down what they are seeing.
D.4.1 Understand that objects are made of more than one substance, by observing, describing and measuring the properties of earth materials, including properties of size, weight, shape, color, temperature, and the ability to react with other substances
Students will be combining different elements together to create molecules, such as water, oxygen, and carbon dioxide.
