Download 8b Isotopes and Ions2

When Atoms
Change…
What we KNOW…
• Atoms on the periodic table are neutral.
• Atoms are neutral because they have the
same number of protons as electrons.
• protons
have a positive charge.
• neutrons
have no charge.
• electrons
have a negative charge.
What we Also need to KNOW…
• The identity of an atom is determined
ONLY by the number of protons.
• For example… If I tell you there is an atom
with 3 protons… you know it’s a Lithium
atom.
• What about 8 protons, 13 protons, 79
protons???
What happens if the number of
neutrons change???
If an atom gains neutrons…
1. The mass increases by 1 for every neutron added.
2. The number of protons and electrons stay the same.
3. The charge remains neutral. (Neutrons don’t have a charge.)
4. The identity of the atom does not change
If an atom loses neutrons…
1.
2.
3.
The mass decreases by 1 for every neutron taken away.
The number of protons and electrons stay the same.
The charge remains neutral. (Neutrons don’t have a charge.)
4.
The identity of the atom does not change
What happens if the number of
neutrons changes???
Only the mass changes!
But when we compare the same types
atoms with different masses we
are comparing isotopes!
.
Isotope: Same kind of atom but with a
different number of neutrons
ISOTOPE EXAMPLE
Most commonly
occurring hydrogen
isotope
Has a mass of 1 and
an atomic number of 1
Less commonly
occurring hydrogen
isotope
Has a mass of 2 and
an atomic number of 1
ISOTOPE NOTATION
We communicate that we are talking about a
specific isotope by using the Atomic
Symbol of the isotope followed by the
“NEW” mass number.
For Example:
The most common isotope of
lithium is:
Li7
Isotope INVENTORY
Completing a particle inventory for an
Isotope is almost the same as the neutral
atom EXCEPT we USE THE “NEW”
MASS NUMBER to calculate neutrons.
Ex: Li-6
3p+ (since it’s Lithium!!!)
3e- (since they are still equal to p+)
3n
Isotope Practice
• Ca atom has a mass of 40.
• The isotopes for Ca are: Ca-42, Ca-43,
Ca-44, Ca-46, & Ca-48.
1.) How many neutrons are in a Ca atom and each of
its isotopes?
2.) What are the differences and similarities between
the Ca atom and its isotopes?
Isotope Practice
Ca atom has a mass of 40. (atomic # or #of P+’s = 20)
The isotopes for Ca have masses of 42,43,44,46, & 48.
To find the number of neutrons you subtract the atomic
number from the mass number.
1.) How many neutrons are in a Ca atom and each of its
isotopes?
Number of Neutrons in each isotope:
Ca40: 40 - 20 = 20n
Ca42: 42 - 20 = 22n
Ca43: 43 - 20 = 23n
Ca44: 44 - 20 = 24n
Ca46: 46 - 20 = 26n
Ca48: 48 - 20 = 28n
2.) What are the differences and similarities
between the Ca atom and its isotopes?
Similarities: All have 20 p+, all have 20 e-,
all neutral, all are Calcium
Differences: The # of neutrons is different,
masses are all different,
nuclear stability changes.
Isotope Inventory HW
Do particle inventories for each of the
following isotopes:
Si-30
Ar-36
Fe-54
Quiz Quick
Isotopes gain or lose…
A.
B.
C.
D.
electrons
protons
neutrons
nuclei
More Isotope Practice
1.)How many neutrons are in each of Zinc’s
isotopes?
Zn-64____ Zn-67_____ Zn-70____
2.) What are the differences and similarities
between the Zn atom and its isotopes?
What happens if the number of
electrons change???
If an atom gains electrons…
1. The mass stays the same (electron’s mass = 0).
2. The number of protons and neutrons stays the
same.
3. The charge becomes negative. (There are more
negative e- than positive p+ now!)
If an atom loses electrons…
The mass stays the same (electron’s mass =0).
The number of protons and neutrons stays the
same.
3. The charge becomes positive. (There are less
negative e- than positive p+ now!)
1.
2.
What happens if the number of
electrons changes???
The atom is now called an
ION!!!
Ion- An atom that has gained or lost
electrons.
ION EXAMPLE
H+ is a
positive
charged
hydrogen
ION
Or Cation
H: Is the
neutral or
regular
hydrogen
atom
H- : is a
negative
charged
hydrogen
ION
Or Anion