Atomic Structure
•Basic Parts of the atom- Subatomic
Particles
• Proton
Positive charge
• Found in the nucleus
• Dictate the identity of the atom
•
• Neutron
No charge
• Found in the nucleus
•
• Electron
Orbits the nucleus
• Tiny compared to proton and neutron
• # equal to # of protons in neutral atom
•
•Parts of the atom
• Nucleus
Consists of protons and neutrons
• Extremely dense
•
• If
the nucleus of an atom was the size of a 1cm
ball, it would weight 133,000,000 tons!
• Electron
•
Area outside the nucleus where the electrons
orbit the nucleus
• Empty
•
cloud
space
If the nucleus was the size of golf ball, the
electron cloud would be half a mile in
diameter
•Electron Cloudss
• Only
a certain # of electron can
occupy a particular area at once
•
Known as energy levels
• Level
1- 2 electrons
• Level 2- 8 electrons
• Level 3- 18 electrons
• Level 4- 32 electrons
•Identifying Atoms
• Atomic
•
Number
Determined by the number of protons
• All
atoms of a particular element will have the
same atomic number
• Different elements have different atomic numbers
•Checkpoint!
•
What is the atomic number for the following elements?
• Oxygen
• Neon
• Iron
• Lithium
• Phosphorous
• Mercury
•Atomic Mass
• The
mass of the nucleus of an atom
Protons + neutrons
• If we know atomic mass and atomic number,
we can determine the number of neutrons
•
•Checkpoint!
•
What is the atomic mass for the following elements?
How many neutrons would each element have?
•
Oxygen
•
Neon
•
Iron
•
Lithium
•
Phosphorous
•
Mercury
•
•Isotopes
• Atoms
of the same element whose
atomic masses are different
• Two ways of identifying
•
Hyphen notation
• element
name-atomic mass
• Ex- Carbon-12
•
Chemical notation (nuclear symbol)
• atomic
mass written over atomic number followed
by atomic symbol
• Ex: 6 C
12
•
Again, we can identify # of neutrons from
atomic mass and atomic number
•Checkpoint!
•
Write the Chemical formula and hyphen notation for the
following:
•
Nitrogen atom with 7 neutrons
•
Carbon atom with 8 neutrons
•
Sulfur atom with 15 neutrons
•
Lithium atom with 2 neutrons
•
Neon atom with 12 neutrons
•Average Atomic Mass
•
•
•
•
Weighted average of masses of all naturally
occurring isotopes of an element
This is the value you see on the periodic table
Calculated by multiplying each isotopes mass by the
decimal percentage and adding those values
together.
EX: Carbon-12: 98.5%
Carbon-13: 1.0%
Carbon-14: 0.5%
•Checkpoint!
•
Calculate the average atomic mass for the following:
Uranium-234: 0.005%
Uranium-235: 0.720%
Uranium-238: 99.275%
Copper-63: 69.17%
Copper-65: 30.83%