1. How To Draw an Atom Notes
Unit 3:
How To Draw an Atom Notes

2. Chemical Symbol
AKA Atomic Mass
Chemical Name 7 N
Nitrogen
14.007

3. PROTONS (positive + charge):
The atomic number is equal to the number of protons.
Nitrogen’s atomic number is 7. Nitrogen has 7 protons in its nucleus.
Every atom of nitrogen contains 7 protons. If an atom does not have 7 protons, it cannot be an atom of nitrogen.

4. ELECTRONS (negative – charge):
Atoms have no overall electrical charge…That means that there must be a balance between the positively charged protons and the negatively charged electrons.
Atoms must have equal numbers of protons and electrons.
Nitrogen has 7 protons, therefore nitrogen has 7 electrons.
An atom can gain or lose electrons, becoming what is known as an ion. An ion is an electrically charged atom.
If an atom has more electrons than protons, the atom has a negative charge and is called an anion. (N-)
If an atom has more protons than electrons, the atom has a positive charge and is called a cation. (N+)

5. NEUTRONS (no charge):
Find the mass number by rounding the atomic weight/atomic mass to the nearest whole number.
Nitrogen’s atomic weight is which would round to 14.
The mass number is a total count of the number of particles in an atom’s nucleus. (Remember that the nucleus is made up to protons and neutrons.) So we can write…
Mass Number = (number of protons) + (number of neutrons)
For Nitrogen, this equation becomes:
Number of Neutrons =
Adding or removing a neutron from an atom does not create a different element, it just creates a lighter version of that element called isotopes.

6. Where do these particle go in the atom?
Protons and Neutrons stick together in the nucleus.
Electrons belong in the energy levels.
1st energy level holds 2 electrons.
2nd energy level holds 8 electrons.
3rd energy level holds 8 or 18 electrons

7. In Summary… Number of Protons = Atomic Number
Number of Electrons = Number of Protons = Atomic Number
Number of Neutrons =
Mass Number – Atomic Number

8. DRAW A NITROGEN ATOM: