Name:
ChemComm
NOTES: Atomic Structure - Atoms, Isotopes, and Ions
1. The three particles that make up the atom are:
2. The proton(s) and neutron(s) are found in the
3. The electron(s) are found
the nucleus,
4. The proton has a
charge, the neutron has a
(no) charge, and the electron has a
charge.
5. The structure of the atom looks like this:
6. The atomic number tells us the number of
7. The mass number tells us the number of
in the atom.
in the atom.
+
8. The nuclear symbol looks like this:
Mass Numl)er ~,
Atomic Numberl~’ leme~l[° Symbol
Example: 147N
This nuclear symbol tells us that the element is Nitrogen (N), that
nitrogen has 7 protons, and has 14 protons + neutrons
9. How many neutrons does it have then?
10. In a neutral atom, the number of protons equals the number of electrons.
How many electrons does this example atom have?
Exam 31es ~ Try these:
# of
protons
Nuclear
Symbol
# of
electrons
# of
Atomic
Number
Number
~Na
36
45
52
62
52
You have more problems to do for classwork/homework
Isotopes
Isotopes are atoms of the same element that differs in the number of
Example:
Carbon-12 is the graphite in your pencil
Carbon-14 is how we date fossils and mummies
Carbon ALWAYS contains 6 protons, but Carbon-12 contains 6
neutrons and Carbon-14 contains 8 neutrons
In the example above, the 12 and 14 in Carbon-12 and Carbon-14 is the mass
number.
Carbon-12 -- ~C and Carbon-14 : ~C
Examples - Convert the following symbols:
Nuclear Symbol
Isotope Name
I~C
Carbon-12
40
llranium-238
You have more problems related to isotopes for classwork/homework
1. Ions are atoms of the same element that differ in the number of
2. There are two types of ions:
and
have a positive charge
have a negative charge
3. When an ion has a negative charge, it is because there are
electrons than protons
4. When an ion has a positive charge, it is because there are
electrons than protons
THIS IS IMPORTANT: An ion has a positive charge because it has
FEWER electrons, NOT because it has MORE protons!! If we change the
number of protons, it is no longer that element.
We can add another piece of information to the nuclear symbol - the
charge of the ion
7 protons
8 neutrons
7 electrons
7 protons
8 neutrons
10 electrons (3 more)
7 protons
8 neutrons
2 electrons (5 less)
Try these:
Nuclear
Symbol
# of
protons
# of
electrons
# of
neutrons
13
10
14
23 1+
ilNa
1~02-
Atomic
Number
Mass
Number