Download Review of Major Concepts Taught in Grade 9 Chemistry

Review of Major
Concepts Taught in
Grade 9 Chemistry
Structure of the Atom:
 An atom is made up of the following subatomic particles:
o Protons - have a positive charge and are found inside
the nucleus. A proton has a mass of 1 a.m.u. (atomic
mass unit)
o Neutrons - have no charge and are found inside the
nucleus. A neutron has a mass of 1 a.m.u.
o Electrons- have a negative charge and are found
outside the nucleus in orbitals or shells . An electron’s
mass is 1/2000 of a proton or neutron’s mass.
Determining the Number of Subatomic Particles:
•The atomic number of an element tells us how many
electrons and protons it has.
•The atomic mass of an element is determined by
adding the number of neutrons to the number of
protons.
Number of
protons
Number of
electrons
Number of
neutrons
Atomic Mass
Atomic
Number
Element Name
Chemical
Symbol
23
23
28
51
23
Vanadium
V
12
12
12
24
12
Magnesium
Mg
56
56
81
137
56
Barium
Ba
45
30
Scandium
35
59
28
Bohr Models:
 The Bohr model of the atom represents the number of
subatomic particles found in one atom of a certain element.
 When drawing a Bohr model, the nucleus is represented by a
circle which contains the element symbol, the number of
protons and the number of neutrons.
 The electrons are drawn in orbitals (also called electron
shells or energy levels) outside of the nucleus.
 The first orbital can hold a maximum of 2 electrons. The
second orbital can hold a maximum of 8 electrons and the
third orbital can hold a maximum of 8 electrons.
Bohr Model for Fluorine
Hydrogen Bohr Model
Helium Bohr Model
Magnesium Bohr Model
Oxygen Bohr Model
Valence Electrons:

Valence electrons are the electrons found in the outermost electron orbit or
shell.

An element’s valence number provides information about what type of ion
that element will form and how it will combine with other elements to form
compounds.
How many valence electrons do each of the
following elements have?

Flourine: ______________

Hydrogen: ______________

Helium: ______________
How many valence electrons do each of
the following elements have?

Magnesium: ______________

Oxygen: _______________
Periodic Table:

The periodic table is an arrangement of elements based on increasing atomic
mass.

Elements are arranged into vertical columns called groups or families.

Elements are also arranged into horizontal rows called periods.

Elements that are found in the same group or family share similar properties.

Elements in the same group also have the same number of valence electrons.

Grab the following marker colours:

Red

Orange

Yellow

Green

Blue

Purple
Chemical Families:

Hydrogen Family (RED) – Contains only one element, Hydrogen. Hydrogen has
1 valence electron that it either loses, gains or shares when bonding with
other elements. This makes it unique.

Alkali metals (ORANGE) – Found in group 1 on the periodic table. Have 1
valence electron. Very reactive. Alkali metals tend to lose electrons when
forming compounds.

Alkaline Earth Metals (YELLOW) – Found in group 2on the periodic table. Have
2 valence electrons. Alkaline Earth metals tend to lose electrons when
forming compounds.

Chalcogens (GREEN) – Found in group 6 on the periodic table. Have 6 valence
electrons. Chalcogens tend to gain electrons when forming compounds.

Halogens (BLUE) - Found in group 7 on the periodic table. Have 7valence
electrons. Very reactive. Halogens tend to gain electrons when forming
compounds.

Noble Gases (PURPLE) - Found in group 8 on the periodic table. Have 8
valence electrons or a full outer shell. Noble Gases are considered inert
which means they do not react.
