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Atomic Structure Electrons Protons Neutrons
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Reading the Periodic Table:Element Squares
Atomic Structure
Nucleus
Electron Cloud
Atomic StructureElectrons
Protons
Neutrons
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 bondshave the same number ofelectrons as protons.
Atomic # can be used toInfer 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 atomIs found in the nucleus
Only protons and neutronsconsidered to have mass
Calculate # neutrons from Atomic mass
Neutrons and P. TableAtomic 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
Au196.979
FamiliesColumns = Families (or groups)
•Family members share common properties
Periods• Period = Row
• Row number = # energy levels ( shells)