Download Atomic Structure and Isotopic symbols

Atomic Structure
Isotopes
Atomic Structure
particle
proton
symbol
p+
location
nucleus
charge
1+
mass
1 amu
neutron
no
nucleus
0
1 amu
No charge
electron
e-
Electron
cloud
1-
1/1840 amu
Matter
Atoms
nucleus
Neutrons
protons
electron cloud
=
electrons (in a neutral atom)
• The number of protons in an atom equals it’s atomic number
• Every atom has a unique atomic number
• Since electrons are easily gained or lost they determine the
overall charge of an atom
Isotopes
• Atoms with the same number of protons but
different numbers of neutrons
• Another way to say – atoms of the same
element with different numbers of neutrons
• An elements mass number is the number of
protons plus the number of neutrons
• REVIEW: to determine the number of
neutrons subtract the atomic number from the
mass number
• Mass # – atomic # = # of neutrons
Isotopes of Lithium
Isotopic symbols
Isotopic symbols
NOTE: Unlike on the periodic
table where the atomic number
is at the top of the box and the
average atomic mass is at the
bottom in isotopic symbols the
mass number is at the top and
the atomic number is at the
bottom.
If X is Hydrogen and its mass number is 2 then the isotopic symbol
would be
2H
1
Isotopic symbols
If X is Fluorine and its mass
number is 20 then the correct
isotopic symbol is
Fluorine – 20.
If the atom has a charge the charge is written
to the upper right side of the symbol. If the
charge is either negative or positive 1 the 1 is
not written but understood to be 1.
Determine the number of neutron in each isotope
1. 238 – 92 = 146 neutrons
2. 84 – 36 = 48 neutrons
3. 35 – 17 = 18 neutrons
4. 14 – 6 =
8 neutrons