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Up and Atom!
What is an Atom?
An atom is the smallest part of an element that
can exist.
Atoms have a neutral charge.
Atoms are composed of protons, neutrons, and electrons.
Atom Anatomy
Subatomic
Particles
Symbol
Charge
Location
Mass
Proton
p
+1
Nucleus
1.0 g/mol
Neutron
n
neutral
Nucleus
1.0 g/mol
Electron
e-
-1
Outside
Nucleus
.0005
g/mol
Generic Notation
A
X
Z
X - Element Symbol
A - Atomic Mass
Z - Atomic Number
Determining the number of
subatomic particles
Particle
Proton
Neutron
Electron
How to determine number
Proton = Atomic Number
Neutron = Mass - Atomic Number
Electron = Proton
Octet Rule
The octet rule is the tendency for atoms to lose or gain
electrons in order to have a full set of eight.
Outermost eare called:
Nucleus
2e- 8e- 8e- Valence electrons
Ions
When an atom loses or gains electrons, it becomes an ion.
Two types of ions:
1. Cations are positively charged ions.
2. Anions are negatively charged ions.
Loses electrons
Gains electrons
Ions Continued
An ion composed of only one type of atom
is a “monatomic ion.”
Ex. Li+and S-2
An ion with more than one type of atom
is a “polyatomic ion.”
Ex. NH4+ and SO42-