What is an atom???

1
What is an atom???

• An atom is the smallest particle of an element
  that retains its identity in a chemical reaction.

2
What are the parts of the atom???

• 1.) Protons
• 2.) Neutrons
• 3.) Electrons

Positively charged!!
Neutral
Negatively charged
3
What information do we get about an atom from
the Periodic Table of Elements?
Mass number of protons of neutrons
Atomic number of protons (ID of an element)
of protons of electrons
of protons of electrons
Electron configuration How many electrons can you
count??
4
Where are protons, neutrons, electrons located
in an atom?

• John Daltons Model of the Atom

Atoms are tiny, indestructible particles, with no
internal structure.
5

• J. J. Thomsons Model of the Atom

Plum Pudding Model
6

• Ernest Rutherfords Model of the Atom

Rutherfords Gold Foil Experiment
7
Ernest Rutherfords Model of the Atom
The nucleus is the tiny, central core of the
atomcontains protons neutrons
The electrons are distributed around the nucleus
and occupy most of the volume of the atom.
8

• Niels Bohrs Model of the Atom

Planetary Model of the Atom
Electrons move in circular orbits at fixed
distances from the nucleus.
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• Given Mass 43
• of electrons 21
• a.) How many protons does this atom have?
• protons of electrons
• b.) What is the identity of this atom?
• of protons atomic
• c.) How many neutrons does this atom have?
• mass protons neutrons