1. Structure of an Atom & The Charge of An Atom
Nucleus with Electron Cloud & Orbitals
Nucleus with Electrons Orbiting Nucleus
Nucleus with Electrons in Circular Energy Levels (Bohr)

2. What is an Atom? Protons Electrons Neutrons
An atom is the smallest building block of matter.
An atom is the smallest piece you can break matter into and still have a unique type of matter.
Atoms make up ALL matter!!!!!
Atoms can be broken down into smaller pieces called SUBATOMIC particles.
These subatomic particles are called:
Protons
Electrons
Neutrons

3. PROTONS
Protons are located in the center part of an atom – CALLED THE NUCLEUS.
Protons have a POSITIVE charge.
The number of protons determines the type of atom.
ALL URANIUM ATOMS HAVE 92 PROTONS IN THEIR NUCLEUS
ALL HELIUM ATOMS HAVE 2 PROTONS IN THEIR NUCLEUS
ALL HYDROGEN ATOMS HAVE 1 PROTON IN THEIR NUCLEUS

4. Neutrons
Neutrons are located in the center part of an atom – CALLED THE NUCLEUS.
Neutrons have NO charge. They are NEUTRAL.
Two of the same type of atom must have the same number of Protons but can have different numbers of Neutrons.
ALL URANIUM ATOMS HAVE 92 PROTONS IN THEIR NUCLEUS BUT CAN HAVE 142, 143 OR 146 NEUTRONS IN THEIR NUCLEUS
ALL HELIUM ATOMS HAVE 2 PROTONS IN THEIR NUCLEUS BUT CAN HAVE 1, 2 OR 3 NEUTRONS IN THEIR NUCLEUS
ALL HYDROGEN ATOMS HAVE 1 PROTON IN THEIR NUCLEUS BUT CAN HAVE 0, 1 OR 2 NEUTRONS IN THEIR NUCLEUS

5. Nucleus of an Atom The central part of an atom is called the NUCLEUS.
The nucleus of an atom contains the Protons & Neutrons.
More than 99% of the mass of an atom is contained in the nucleus.
Less than 1% of the total volume of an atom is the nucleus.
This means that an atom is mostly empty space.

6. Electrons
Electrons are located outside the nucleus of an atom in an electron cloud.
However we will use the Bohr Atom as our model where the electrons are in rings around the nucleus called energy levels.
Electrons have a NEGATIVE charge.
The number of electrons compared to the number of protons determines the charge of the atom.
Atoms with an electric charge are called IONS.
If an atom has the same number of protons as electrons, then the atom is neutral.
If an atom has more protons than electrons then the atom has a positive charge.
If an atom has more electrons than protons, then the atom has a negative charge.

7. Finding the Charge on an Atom
An atom has 6 protons and 4 electrons. What is the charge on this atom?
p – e = charge
6 – 4 = 2
So the ION has a +2 charge

8. Finding the Charge on an Atom
An atom has 29 protons and 46 electrons. What is the charge on this atom?
p – e = charge
29 – 46 = -17
So the ION has a -17 charge

9. Finding the Charge on an Atom
An atom has 15 protons and 15 electrons. What is the charge on this atom?
p – e = charge
15 – 15 = 0
So the ATOM has 0 charge
It is NEUTRAL