1. Warm-up
When looking at an atom, how might we determine what element that atom is from?

2. The ugly parts to the atom
SUBATOMIC PARTICLES
The ugly parts to the atom

3. Subatomic particles Atoms consist of 3 types of subatomic particles
Protons
Neutrons
Electrons

4. Protons Protons have a positive charge
Found in the center of the atom called the nucleus
Usually represented with the symbol “p+”
The number of protons determine which element a particular atom is

5. Neutrons Neutrons have no charge or a neutral charge
Found in the nucleus
Number of neutrons of a particular element may vary, but b/c they are neutral there is no change in charge
When the number of neutrons vary for a particular element we call it an isotope

6. Electrons Electrons have a negative charge
They reside in the electron cloud away from the nucleus
They are smaller than both the neutron and proton
Electrons determine how an element will react

7. Atomic Number Games The # of protons = the number of electrons
The # of protons = atomic number
The # of protons + # neutrons = atomic mass
Atomic mass – atomic # = # of neutrons
NOTE: IF THE # OF PROTONS CHANGE, SO MUST THE ELEMENT

8. Relative Size of Particles
Protons and Neutrons are about the same size in terms of mass
An electron is about 1/1836 the size of a proton
This means that electrons are VERY small in comparison to protons and electrons

9. Isotopes
An isotope of an element is an element that has the same atomic number but its atomic mass may vary
This variation occurs because the number of neutrons can change without affecting the charge of the atom
Remember ALL ELEMENTS HAVE AN OVERALL CHARGE OF ZERO