Transcript ATOMIC STRUCTURE

ATOMIC STRUCTURE
Label the following:
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Nucleus
protons
neutrons
electrons
Simplified view of the atom
Protons = positive charge +
electrons= negative charge neutrons= no charge 0
ATOMIC MASS
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Inside the nucleus (mainly)
protons + neutrons
unit is AMU
find on periodic table (round to whole #)
ATOMIC NUMBER
 Number of protons
 cannot change!
 Identifies element
IONS
 Charged atoms: NOT neutral
 p> e positive
 p< e negative
 example: 11p 11e 12 n neutral Na
» 11p
10 e
12n
ion
Na+
ISOTOPES
 Different number of neutrons than stable
atom
 usually radioactive
 atomic mass is different than stable atom
 example:
234U
History of atomic stucture
ttp://atomictimeline.net/index.php
 Rutherford’s experiment
Can we see atoms?
 STM- scanning
tunneling microscope
 Invented 1981
 Shows arrangement of
atoms
 Gold
 element- same atoms bonded together
 Compound- two (or more) different atoms bonded
 Mixtures- two (or more) different materials NOT
bonded
 Minerals?-
WORKSHEET
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P=
e=
n=
atomic mass=
atomic number=
how to recognize an ion?
How to recognize an isotope?
TO CALCULATE # OF
NEUTRONS
 Atomic mass (p+n)
 atomic number (p)
 SUBTRACT!
Sample problems
 11 p 12 n 10 e
 19 p 21n 19 e
 25 p 30 n 21 e
 Cr+3
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234
Pu