HOW DO YOU DETERMINE THE AMOUNT
OF SUBATOMIC PARTICLES IN AN ATOM?
IT BEGINS WITH THE PERIODIC TABLE

An arrangement of elements in which the
elements are separated based on properties
DISTINGUISHING ELEMENTS

The atomic number of every element
represents the number of protons in the
nucleus of an atom of that element.
MASS NUMBER

The total number of protons and neutrons in an
atom.
Number of neutrons = mass number – atomic number
Chemical Symbol Shorthand Notation
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WHAT ABOUT ELECTRONS?

Electrons in an atom are equal to the number
of protons.
FORCE OF THE NUCLEUS

The nucleus is made of p + n

2 protons are close together there is a strong
attraction
 Nuclear
Force
ISOTOPES

Atoms (of the same element) that have the
same number of protons but a different
number of neutrons.
Do Isotopes have different mass numbers?
COMMON ISOTOPES

Hydrogen
 Hydrogen-1
(Hydrogen)
 Hydrogen-2 (Deuterium)
 Used
as a moderator in nuclear reactors
 Hydrogen-3
 Used
(Tritium)
in the production of Hydrogen bombs
PRACTICE!

There are 3 isotopes of Oxygen. Oxygen-16,
Oxygen-17 and Oxygen 18. Write each in
shorthand notation.

There are 3 isotopes of Chromium. Chromium50, Chromium-52 and Chromium-53. How
many neutrons are in each isotope?
ATOMIC MASS UNITS

One twelfth of the mass of a carbon-12 atom
IF THERE ARE ISOTOPES HOW DO YOU
CALCULATE 1 ATOMIC MASS?

Calculate a weighted average
 Not
 You
each isotope is as common as the next
need to know the mass of each isotope and its
natural abundance.