chapter 6: an introduction to atoms. atomic theory development key players – democritus – dalton...
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Chapter 6:
An Introduction
to Atoms
Atomic Theory Development
• Key Players–Democritus–Dalton– Thomson–Rutherford–Bohr
the atom
• Literally means…– Not able to be divided
• It is the smallest item that
an element can be divided
and still be the same
element.
the atom
• How small is an atom?
JJ Thomson
• Plum Pudding Model– Aka Chocolate Chip Ice Cream Model
Ernst Rutherford
• at the center of an atom–Nucleus
Subatomic particles
• Protons– Positive charge
• Neutron– Neutral charge
• Electron– Negative charge
the atom
Subatomic particles
• Location– Nucleus• Protons & neutron
– Electron Cloud• Electron
• Mass– Only protons and neutrons are measurable– Electrons way too small to measure
Isotopes
• Protons stay the same but…– Neutrons either increase or decrease– Changes the atomic mass
isotopesWhat is this
element?
Silver
What is the atomic mass of
this isotope?
108
atomic measurement
Atomic Mass Unit
Atomic Mass
Mass Number
atomic measurement
• Atomic Mass Unit– Unit that describes the mass of an atom
• Atomic Mass– Weighted average mass of all natural isotopes of
an elements• Mass Number– Sum of the protons and neutrons
Mass number
Mass Number…… 13
# of Protons……… - 6_____________________# of Neutrons….. 7
Terms to Know
Atom
Electrons
Electron Cloud
Isotopes
Protons
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