```Reading the Periodic Table:
Element Squares
Atomic Structure
Electron Cloud
Nucleus
Atomic Structure
Electrons
Neutrons
Protons
Protons
In the nucleus
A Positive(+) charge
Mass = 1 a.m.u
Determine the
element
• Determine the
atomic number
•
•
•
•
Protons
Protons and P. Table
Atomic # = a whole #
Atomic # = # protons
Electrons
• In electron cloud
• In Unbound atom
are equal in
number to protons
• Negatively
charged
• Mass=1/1800 amu
e
e
Electrons and P. Table
The atomic # = # protons
Atoms not involved in bonds
have the same number of
electrons as protons.
Atomic # can be used to
Infer the number of electrons
Neutrons
• In the nucleus
• No charge
(neutral)
• Mass = 1 a.m.u.
• “glue” nucleus
together
Neutrons and P. Table
All the mass of an atom
Is found in the nucleus
Only protons and neutrons
considered to have mass
Calculate # neutrons from
Atomic mass
Neutrons and P. Table
Atomic mass - Atomic # = # neutrons
1. Round atomic mass to nearest
whole number
Ex. # neutrons in helium
Atomic mass = 4.006 =4
Atomic # = 2
4 - 2 = 2 neutrons
Test yourself
• Element name?
• Gold
• # protons?
• 79
• # electrons?
• 79
• # neutrons?
• 118
79
Au
196.9
Families
Columns = Families (or groups)
•Family members share common properties
• Period = Row
Periods
• Row number = # energy levels ( shells)
```