1. Gathering Atomic Information
Almost all of the information you need to know about a particular element can be found by looking at the periodic table. The periodic table will typically have one of the following formats:

2. If this stadium were the size of an atom’s electron cloud, the nucleus would be the size of a marble setting on the 50 yard line. Electrons occupy the VOLUME, protons and neutrons constitute the MASS of an atom.

3. Subatomic Particles
Protons and electrons are the only particles that have a charge.
Protons and neutrons have essentially the same mass.
The mass of an electron is so small (2000 time smaller than the proton), we ignore it.
Table 2.1
is the way to write this number!

4. What do all atoms of the same element have in common?
***Atoms of the same element always contain the same number of protons!***

5. What is the name of the two numbers on an element’s square of the periodic table?
Atomic Number:
Smallest of the two numbers
Always a whole number
Indicates number of protons
Average Mass
Average number of protons (p+) and neutrons
Usually a decimal
Mass Number
# of protons and neutrons added together
round the average atomic weight to the nearest whole number to find the most common combination of p+ and n (isotope)
Carbon
12.011 C 6 6 C
Carbon
12.011
Go to the PT

6. How to find number in an atom
What information can be obtained from the two numbers on a square of the periodic table?
Subatomic Particle
&
symbol
Charge
Mass
(amu)
Location
(region)
How to find number in an atom
Founder and Date
Proton
(p+)
Positive
(+) 1
Nucleus
Same as atomic number
E. Rutherford
1914
Neutron
(n) or (0)
Neutral
Mass #
-Atomic #
# Neutrons
J Chadwick
1932
Electron
(e-)
Negative
(-)
Electron cloud
Same as atomic number in a neutral atom
JJ Thomson
1897

7. How are the particles related?
Atoms
Region
Nucleus
Electron Cloud
Subatomic
Particle
Proton
electron
Neutron -
Charge +
Charge Balance

8. Atoms of the same element that have different number of neutrons
Isotope
Atoms of the same element that have different number of neutrons

9. Models of Carbon Isotopes
Carbon-12 Carbon-13 Carbon-14
6p+ 6n
6p+ 7n
6p+ 8n
How are isotopes of the same element identified?
Isotopes are identified by the name of the element and by the atom’s mass number (written like Li-6 or Li-7)
It’s called ISOTOPE NOTATION

10. Lithium Isotope Examples
Isotope Name
Symbol
# protons
# neutrons
# electrons
Lithium-6
Li-6 3
Lithium-7
Li-7 4
Chlorine-35
Cl-35 17 18
Chlorine-37
Cl-37 20

11. How to find Mass Number
Number of protons AND neutrons (added together) of a specific isotope of an element.
Mass Number = #p + #n
Found one of two ways (prioritized)
Given to you after the element symbol (isotope notation)
C-14 or Na-23
100% accuracy
Most common isotope method (mci). Round the average atomic mass value from the periodic table to the nearest whole number
Carbon’s Atomic mass is = round to 12
Manganese’s Atomic mass is = round to 55
50% accuracy