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Atoms and Elements
By Jose Andres HernandezGodoy and Mr. Lin
Atomic Vocabulary
• Ion: A charged atom. Not neutral. There is
either more electrons than protons or more
protons than electrons. This does not change
the element because the same amount of
protons exist.
– Hydrogen with one proton and one electron is neutral
but is not stable. A stable Hydrogen will have two
electrons, making it a negative ion.
• Isotope: An atom with more or less neutrons.
As a result, the atomic mass is affected, but not
its atomic number.
2
This is an
example of
Helium (He).
He
e
Its atomic mass is
4.002 AMU
2 Protons = 2 AMU
2 Neutrons = 2 AMU
The remaining 0.002
refer
to the mass of the
electrons
4.002
P
N
N
e
P
3
This is an
example of
Lithium (Li).
e
Its atomic mass is
6.941 AMU
3 Protons = 3 AMU
3 Neutrons = 3 AMU
The remaining 0.941
refer
to the mass of the
electrons
Li
6.941
P N P
N N
P
e
e
5
e
This is an example of
Boron (B)
B
e
10.811
Its atomic mass is 10.811 AMU
5 Proton= 5 AMU
5 Neutrons = 5 AMU
The remaining 0.811 refer
to the mass of the electrons
N
N P
P
P N
N
P N
P
e
e
e
1
This is an
example of
Hydrogen (H)
H
Its atomic mass is
4.002 AMU
1.00794
1 Protons = 1 AMU
0 Neutrons = 0 AMU
The remaining
0.00794 refer
to the mass of the
electron
P
e
Atoms
• Protons: Positive charge
• Electrons: Negative
charge
• Neutron: No charge
Image Courtesy of
http://tharkad.pa.msu.edu/~asteiner/wpcontent/uploads/atom_model_03.gif
• Nucleus: Middle clump of
protons and neutrons.
This is an example of
Carbon (C)
6
e
Its atomic mass is 12.0107
AMU
C
6 Proton= 6 AMU
e
12.0107
6 Neutrons = 6 AMU
The remaining 0.00674 refer
to the mass of the electrons
e
N
N
P
P
NP P N
P P
e
e
e
Stable Atoms
• An atom will be stable if only its outer shell is
completely full.
– Hydrogen is not stable because it has only one
electron in a shell that can hold up to two electrons.
– Lithium is not stable because it has only 1 electron in
an outer shell that can hold up to eight electrons.
• Hydrogen would typically like to gain an electron
to fill up its outer shell.
• Lithium would typically like to lose an electron to
have a full outershell.
Ionic Bond
• When a Hydrogen atom meets a Lithium
atom, the Lithium atom will lose its outer
electron to the Hydrogen.
– Neither atom will have a neutral charge.
• Hydrogen will have a negative charge now
because it now will have more electrons than
protons.
• Lithium will have a positive charge now because it
now will have more protons than electrons.
• The next slide demonstrates an ionic bond
e
P N P
N N
P
P
e
e
e
e
e
P N P
N N
P
P
e
e
Covalent Bond
• When two atoms share possession of
electrons, they bind in a covalent bond.
• When two Hydrogen atoms meet, neither
want to give up an electron, but both
would like to gain an electron.
– As a result, they will “share” their electrons.
P
P
e
e
e
P
P
e
We Are
Stable
Together
!