2. COMPOUNDS AND THEIR PROPERTIES
•Compounds are pure substances which result from
the chemical combination of two or more elements.
•The nature and properties of the elements combined
in the chemical combinations determine the type of
compound that will be formed.
•An ionic compound is formed when a metal (cation)
is bonded with a nonmetal (anion).
•On the other hand, a covalent compound is formed
when both nonmetals are combined which can be
categorized into two namely: polar covalent and
nonpolar covalent compounds.
3.
4. Periodic Table of Elements
•The elements are divided into two categories: metals
and non-metals.
•Metals are located on the lower left of the table and
include typical metals such as iron (Fe) and nickel
(Ni).
•Non-metals are located in the upper right and include
oxygen (O) and nitrogen (N), which are common
gases as well as iodine, which is a solid.
•The position of elements on the periodic table can be
used to predict with a high degree of accuracy the
structure of a wide range of compounds.
5. •Compounds can be of different classes depending on
the number of elements and they can exist as
metallic, ionic, and covalent compound.
𝑚𝑒𝑡𝑎𝑙 + 𝑚𝑒𝑡𝑎𝑙 → 𝑚𝑒𝑡𝑎𝑙𝑙𝑖𝑐 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑
𝑚𝑒𝑡𝑎𝑙 + 𝑛𝑜𝑛 − 𝑚𝑒𝑡𝑎𝑙 → 𝑖𝑜𝑛𝑖𝑐 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑
𝑛𝑜𝑛 − 𝑚𝑒𝑡𝑎𝑙 + 𝑛𝑜𝑛 − 𝑚𝑒𝑡𝑎𝑙 → 𝑐𝑜𝑣𝑎𝑙𝑒𝑛𝑡 𝑐𝑜𝑚𝑝𝑜𝑢𝑛𝑑
6. PROPERTIES OF METAL AND NON-METAL
METALS NON-METALS
Shiny Dull
High melting points Low melting points
Good conductors of electricity Poor conductors of electricity
Good conductors of heat Poor conductors of heat
High density Low density
Malleable and ductile Brittle
7. •Some elements have properties that are not typical.
For example:
•mercury (a metal) has a low melting point and exists
as a liquid at room temperature
•graphite, a form of carbon (a non-metal), has a
high boiling point and is also a good conductor of
electricity
•A substance with a high density means it has a high
mass for its size.
8. substances can be bent or
•Malleable
hammered into shape without shattering,
while brittle substances shatter when bent or
hit.
•Ductile means that a substance can be drawn
out into a long wire without snapping or
breaking.
9. Compound Formation
• Chemical bonds make atoms more stable than they are if non-
bonded. Bond formation involves changes in the electrons of
two atoms and this is achieved by one of two methods:
electron transfer and electron sharing.
• Electron transfer – is the movement of an electron from one
atom to another atom. It involves the creation of ions, which
bond via ionic bonds to form ionic compounds.
• Electron sharing – involves the equal sharing of electrons
between two atoms and the creation of covalent bonds.
Covalently bonded compounds typically have very different
properties from ionic compounds, and they also involve
combinations of different types of elements.
10. Naming Ionic and Covalent
Compounds
•Ionic compounds are generally formed by the
combination of metal (electropositive) and a
nonmetal (electronegative).
•Electropositive elements mainly metals have
the tendency to lose electrons to form positive
ions.
•Electronegative elements, nonmetals, have
the tendency to gain electrons to form
negative ions.
11. To name ionic compounds, we must follow some simple rules or
steps:
1. Use the complete name of the metal (cation)
2. Add the name of the second element (nonmetal) ending with
–ide.
3. Consider the charge of the elements to be combined and
crisscross.
4. If the elements contain the same charge, cancel it.
5. There are two methods by which we can name elements (cation)
with more than one valence or oxidation number.
a. Classical method – the metal with higher oxidation number
makes use of –ic ending while the lower oxidation number is
named ending with –ous.
b. Stock method (developed by Alfred Stock) – the metal cation is
named completely followed by the oxidation number written
inside the parenthesis.
