1. Atomic Structure
Isotopes

2. Atomic Structure particle symbol location charge mass proton p+
nucleus 1+
1 amu
neutron no
No charge
electron
e -
Electron cloud 1-
1/1840 amu

3. nucleus electron cloud
Matter
Atoms
nucleus electron cloud
Neutrons protons = 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

5. 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

6. Isotopes of Lithium

7. Isotopic symbols

8. 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

9. Isotopic symbols
If X is Fluorine and its mass number is 20 then the correct isotopic symbol is
Fluorine – 20.

10. 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.

11. Determine the number of neutron in each isotope
238 – 92 =
146 neutrons
– 36 =
48 neutrons
– 17 =
18 neutrons
– 6 =
8 neutrons