SNC 1D – Chemistry note
Date: ____________
Drawing Bohr-Rutherford Diagrams
To draw a Bohr-Rutherford atom you need to be able to find three things: the
number or protons, number of electrons and the number of neutrons. If we know
how they all fit together we can draw the diagrams.
1. Find the number of protons (atomic number = # of protons)
2. Find the number of electrons (# of protons = # of electrons  it’s a neutral atom)
3. Calculate the number of neutrons (#neutrons = mass number – atomic number)
4. Draw a circle and write the number of each, protons and neutrons, inside the circle
representing the nucleus.
5. Draw shells and fill will the correct number of electrons placed in pairs.
(shell 1 = 2 electrons, shell 2 = 8 electrons, shell 3 = 8 electrons)
(The electrons always fall to lowest possible energy level so fill lower shells first)
Draw these atoms a b-r diagrams
Na
Cl
He
An _______________ is an atom with the same number of protons but different
number of neutrons.
Hydrogen has three different can mass numbers.
hydrogen H1
deuterium H2
C12
C14 (used in carbon dating)
tritium H3