Coordinated Science, Chemistry
“Noble Gas Envy”
Name:
Period:
Purpose: In this lesson you will begin to understand why elements come together in certain combinations
like NaCl, CaCl2 or AlCl3
Valence Electrons, revisited.
1. How does an element’s periodic table Group (column) relate to the element’s valence electrons?
Give two examples:
Noble Gas Envy
2. Except Helium, how many valence electrons do the Noble Gases (Group 8) have? _____
3. All other atoms “want” to be like the Noble Gases! They want a full outer shell of electrons.
READ THAT AGAIN. This is the BIG IDEA!
a. How many more electrons do the elements in Group 7 need (to be like a Noble Gas)? _____
7 electrons + ___ electrons = 8 electrons
b. How many more electrons do the elements in Group 5 need (to be like a Noble Gas)? _____
5 electrons + ___ electrons = 8 electrons
4. Things are a little different on the left (metals) side of the periodic table. They too want a full outer
shell of electrons, but instead of ADDING electrons, they SUBTRACT electrons.
Look at Magnesium (#12) to see why.
a. How many valence electrons does magnesium have? _____
b. How many electrons does magnesium have in the shell below the valence electrons? _____
c. So, if magnesium loses two electrons, how many electrons will be in the new outer shell? _____
d. How many electrons will calcium lose? _____
e. How many electrons will ALL Group 2 elements lose? _____ Group 1? _____ Group 3? _____
5. Things are a little different for Group 4 elements. They might gain OR lose ____ electrons, to end up
with a full outer shell of _____ electrons.
6. Things are also different for the Noble Gases. How many electrons will they gain or lose? _________
7. On the Table of Electron Shells, label each element showing
how many electrons it loses or gains. See sample.
 Label all of the elements before moving on.
8. Describe one or two patterns you notice after labeling.
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________________________________________________
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Gains 1 electron
IONS You are now ready to understand ions!
9. This is the hard part, so pay attention.
a. Recall: Atoms normally have a neutral charge because they have the same number of
___________ (positive charge) and _____________ (negative charge).
b. How will the charge of an atom change if it GAINS electrons? ____________________
c. Name two elements that gain electrons: ____________________________________
d. How will the charge of an atom change if it LOSES electrons? ____________________
Pause and think this through:
> If an atom loses electrons it subtracts a negative. Subtracting a negative =_____________
> If an atom loses electrons, there will be less negatives than positives (protons).
10. In one sentence, summarize the information in question #9.
____________________________________________________________________________
____________________________________________________________________________
11. When an atom develops a negative or positive charge from gaining or losing electrons, it is called
an ION.
a. Definition: An ion is an atom that _____________________________________________
_________________________________________________________________________
b. Negative ions lost / gained electrons (circle the correct answer).
c. Positive ions lost / gained electrons (circle the correct answer).
d. An example of a negative ion is O-2 because oxygen gains _____ electron(s).
e. An example of a positive ion is Al+3 because aluminum loses _____ electron(s).
12. On the Table of Electron Shells, label each
element showing the charge after
electrons have been added or removed.
See examples.
13. Choose 4 colored pencils. Highlight or
color all elements that:
 lose electrons (positive ions)
 gain electrons (negative ions)
 gain or lose electrons
 do not change
Gains 1 electron
Loses 2 electrons
-1
+2
EXTENSION – What it’s all about!
Ions come together to make compounds you’ve used in class like NaCl (salt) and CuSO4 (copper sulfate)
and the flame test chemicals like SrCl 2 and KNO3. It’s all about the ions!
14. Opposites attract. What’s the ion form of sodium? _______ chlorine? _______
They’re opposite! So put them together and what do you get? ______________ (salt!)
15. These are tougher. How many sodium atoms would you need to give up enough electrons for
oxygen? ______ What would the formula be? _______ How many chlorine atoms would be needed
to take magnesium’s two valence electrons? ______ What would the formula be? _______
See if you can come up with three more formulas: __________________________________
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