Download SNC 1D chem chpt2

The Structure of
the Atom
Inside the Atom
Atoms are made of subatomic
particles.
Protons
Neutrons
Electrons
Protons and neutrons are in the
nucleus.
Electrons are found surrounding
the nucleus.
Protons & neutrons
Contribute to most of the mass
of the atom.
Each is 1840 times the mass of
electrons.
Neutrons have no charge
Neutrons and protons are
attracted through “strong force”
attractions.
Protons have a positive charge
The # of protons in the
nucleus of an atom is the
atomic number.
Atomic number identifies
the atom as a particular
element
 EG.
 # of protons?
6
 Atomic number?
6
 element?
 Carbon
 It will always be carbon!
Cannot change.
 If a proton is somehow
removed or added, it will no
longer be carbon!
 The sum of protons and
neutrons is the mass number.
 Mass # is a whole number, so
you will have to round the #
found on the periodic table.
 EG. Carbon: 12.011
 Mass = 12
 Proton = 6
 Neutron = ?
12 - 6 = 6
 The symbols that we use
to represent different
chemicals are the same
in each language,
although we do call
elements different
names.
 We use a standard
atomic notation to
represent elements.
 Mass # is written above,
atomic # below and the
symbol in large letters to
the left.
TRY THIS!
On page 189 of your
textbook, do activity 5-4.
Bohr-Rutherford models
A way of representing the
atomic structure of an element.
Electrons occupy specific energy
levels called shells. Electron
that are further away from the
nucleus have more energy.
You have to fill the shell closest
to the nucleus first.
The first shell can only take 2
electrons, the next one can take
8, the 3rd can take 8 also.
How to Draw it?
5p
6n
1. Draw a circle
(nucleus) and write the
# of protons of that
atom next to a “p”. And
the number of neutrons
next to an “n”.
EG Boron
Proton # = ?
Neutron # = ?
Electrons: 5
5p
6n
Step 2:
determine the #
of electrons in
the atom (same
as proton #)
Draw the energy
levels.
5p
6n
Step 3: Starting with
the closest energy
level to the nucleus,
put in a max of 2
electrons.
Second level can take
a max of 8 electrons
Third level can also
take a max of 8.
For boron, we only
need two levels.
YOU TRY IT!!
Fill in the
BohrRutherford
diagrams for
the first 20
elements.
Isotopes
One of two or more forms of an
element that have the same number
of protons but a different number of
neutrons.
Since each isotope has a unique
mass number, you can specify an
isotope of an element by placing its
mass number after the name of the
element.
EG. Hygrogen-1 and hydrogen-2
Try this: p. 193 #1-8