Notes :
The Bohr Model
&
Happy Atoms/Ions
What atom (element) do
you think this is? How
can you tell?
Bohr Model Diagrams
• Atom is always neutral (=numbers of e- and +)
• Electrons in an atom are arranged in energy
levels (or shells) around the nucleus.
• Electrons in the 3rd energy level have more
energy than electrons in the first energy level.
• Maximum # of electrons in the first energy level
(shell) is 2. Max # of electrons in the second
energy level (shell) is 8.
• The outermost energy level (shell) can
never have more than 8 electrons in it
(2,8,8,...). These outer electrons are called
valence electrons.
Steps to drawing a Bohr
model
• First step: Determine the number of
protons, neutrons and electrons in each
element.
• Second step: Represent the nucleus as a
small circle and indicate the number of
protons and neutrons.
• Third step: Making larger circles,
arrange the electrons around the nucleus.
= Proton
= Neutron
What atom (element) do
you think this is?
Electronegativity
Happy Atoms
• Atoms are “happy” (most stable) when they have
a full shell (2,8,8,…) of electrons.
• To become happy, some atoms (usually metals)
will give up their outermost electrons (valence
electrons) to other atoms.
• This leaves them with fewer electrons than
protons so that overall they have a 1+, 2+ or even
3+ charge. We call these atoms ions.
• Non-metals (right side of periodic table) will
take electrons from metals to fill their outer
shell.
• This means they have more electrons than
protons so that they have a 1-, 2-, or 3- charge.
These atoms are also ions.
The Making of an Ion
Na1+
I’m happy
now. How
about you?
Cl1-
Yep.