Introduction to Ions. Note : Up to this point, we have only discussed neutral atoms but you will now...
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Transcript of Introduction to Ions. Note : Up to this point, we have only discussed neutral atoms but you will now...
Introduction to Ions
Note: Up to this point, we have only discussed
neutral atoms but you will now begin to learn about charged atoms (ions).
The number of protons will NEVER change! If we change the number of protons we change the identity of the element.Ex: #protons = 6 Carbon
# protons = 7 Nitrogen# protons = 8 Oxygen
Periodic Table•To begin, you need to learn a couple of
terms associated with the periodic table:▫Group – column of the periodic table▫Period – row of the periodic table
•Names of Groups:▫Group 1A: Alkali metals▫Group 2A: Alkaline earth metals▫Group 7A: Halogens▫Group 8A: Noble Gases – inert (do not form
ions)
Ions• REMEMBER: the neutral
atoms always have equal numbers of protons and electrons because the charges cancel
Proton (+) + Electron (-)= 0
For an atom to be charged, it must have different numbers of protons and electrons because the charges would no longer cancel.
• There are two types of ions:▫ Cations – positively
charged; has fewer electrons than protons
▫ Anions – negatively charged; has more electrons than protons.
Ions• We can determine the
charge of the atom based on its location on the periodic table.
• We look at the group number (column) and whether or not the atom is a metal or nonmetal.
• Metals form cations (lose electrons) and nonmetals form anions (gain electrons).
Charges
• Groups 1A – 3A: the group number = the charge on the cation Example: Na is in group 1A so it has a charge of +1.
• Groups 5A – 7A: • -(8 – the group number) =
the charge of the anionExample: Chlorine is in group 7A so, -(8 – 7) = -1, thus it has a -1 charge.
Summary• Only the number of
electrons changes.• If the atom gains electrons
it has a negative charge and is called an anion.
• If the atom loses electrons it has a positive charge and is called a cation.
• Metals form cations.• Nonmetals form anions.
• Group 1A = +1• Group 2A = +2• Group 3A = +3• Group 5A = -3• Group 6A = -2• Group 7A = -1• Group 8A = inert
Now lets practice!
What is the charge of a bromine ion?
+1
-1
+2
-2
CORRECT!
Next Question
Incorrect
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Does lithium form a cation or an anion?
cation
anion
CORRECT!
Next Question
Incorrect
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What is the charge of a magnesium ion?
+1
+2
+3
-2
CORRECT!
Next Question
Incorrect
Try Again
Ions can have equal numbers of protons and electrons.
True
False
Incorrect
Try Again
CORRECT!