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Ions and Isotopes
Ions - Charged Atoms
 The identity of an element is determined by the number of _________________ in its nucleus.
o Therefore if we change the number of ______________ we change the _______________
 HOWEVER, If we change the number of electrons we do not change the element…
instead, we have simply changed the overall _______________________ of the atom.
 Atoms can either _______________ or _____________ electrons.
 Any time an atom becomes charged, we call it an ________________.
o If an atom gains electrons, it becomes a ____________________ charged ion.
o If an atom loses electrons, it becomes a _____________________ charged ion.
Test Yourself! Complete the table below:
Element
Neon
Number of
protons
Number of
electrons
10
10
13
10
17
18
7
9
Net charge
Ion?
(Y/N)
symbol
How Many Electrons Gained or Lost?
 Atoms can become stable with a full valence shell of electrons.
 Therefore, atoms will gain or lose the fewest number electrons possible to achieve a full valence
o
Metals
tend to ______________ electrons to become ___________________ ions
o Non-metals tend to ______________ electrons to become ___________________ ions
 Example: Magnesium (Mg) is a metal with _____ valence electron
To get a full outer shell it can either gain ____ electrons or lose ____ electrons.
Therefore, it is more likely to __________ electrons and form the ______ ion.
Bohr Diagrams for Ions
 Bohr diagrams for ions have two modifications:
1. place square brackets around the whole diagram
2. write the charge in the top right corner, outside the brackets
Practice: On a separate sheet of paper, try drawing the Bohr diagrams
for K+, Be2+, N2-, and FNow try the H+ ion… neat eh?
example: Oxygen Ion (O2-)
Isotopes – Changing the Atomic Mass
Remember: There are 3 sub-atomic particles; protons, electrons and neutrons.
Change the number of protons and you change the element
Change the number of electrons and you create an ion
Question: What happens when you change the number of neutrons?
 Sometimes atoms either gain or lose neutrons.
 Since neutrons have _________________________ this does not affect the charge of the atom.
 Neutrons have about the same _______________ as protons, so a change in the number of
neutrons results in a change in the _____________________________________ .
 Any time an atom has a different mass than is listed on the periodic table, we call it an
_________________________. This means it has gained or lost ______________________.
Example:
24
a) 12
26
b) 12
Mg
Mg
12
Mg
p=
p=
Magnesium
e=
e=
24.305
n=
n=
Magnesium as seen
on a periodic table
These two atoms of Mg have the same number of __________________ and __________________ ,
but a different number of _______________________ . Which one is the isotope? _____________.
Practice – Use your periodic table to help complete the table below
Name of Element
Symbol
Atomic
Number
Relative
Atomic
Mass
Number
of
Protons
Number
of
Neutrons
Number
of
Electrons
Net
Charge
Cu 
62
29
oxygen
15
0
21
35
80
18
36
+2
Ion?
(Y/N)
Isotope
(Y/N)