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 / Number of protons / Number of electrons / Net charge / Ion?(Y/N) / symbol
Neon / 10 / 10
13 / 10
17 / 18
7 / 9
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 example: Oxygen Ion (O2-)
¨ 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 F- Now try the H+ ion… neat eh?
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: a) b)
p = p =
e = e =
n = n =
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 / RelativeAtomic Mass / Number of Protons / Number of Neutrons / Number of Electrons / Net Charge / Ion?
(Y/N) / Isotope
(Y/N)
oxygen / 15 / 0
21 / 18 / +2
35 / 80 / 36