2. At the end of the lesson, we can:
Write the LED structure of a certain element;
Explain how ionic and covalent bond are
formed;
Name and write the chemical formula of
compounds; and
Realize the importance of bonding with
others.
8. It is a shorthand method which consists of a
symbol of the element surrounded by dots. The
symbol represents the nucleus of the atom while the
dots represents the valence electrons of the atom.
10. STEP 1
Write the chemical symbol of the atom
Carbon chemical symbol is
11. STEP 2
Determine the column or group where an atom
belongs in the periodic table or write down its
electron configuration to find out the atom’s
number of valence electrons.
For representative elements, the number of valence
electrons is the same as the atom’s group number
or column.
12. STEP 2
Carbon, a representative element, belongs to
group 4A; therefore, its number of valence electron
is four
Carbon with six electron configuration 1s22s22p2
this reveals that carbon has four valence electrons.
13. STEP 3
Draw the dots that corresponds to the number of
the atom’s valence electrons. Distribute the dots
evenly; it may be placed above or below and/or
either side of the chemical symbol
14. Let us try to draw the LEDS of Fluorine atom (F)
Step 1: F
Step 2: Fluorine belongs to Group 7A. Its electron
configuration is 1s22s22p5 . Therefore, fluorine has
seven valence electrons.
Step 3:
24. These refers to compound bound together by a
strong attractive force.
25. A type of chemical bond formed
when there is a transfer of electrons
from one atom to another. It is also
a type of bond between metal and a
non-metal.
27. This type of bond involves the
gaining and losing of electrons.
The atoms becomes charged particle
called ION.
Cation- positively charged ion, atom
that loses electron
Anion- negatively charged ion, atom
that gains electron.
40. What is
chemical
formula?
It is a shorthand method in
writing the name of the
compound. It shows to
present the elements and
the subscript to represent
the exact number of atoms
used.
41. To write the chemical formula:
• Write the symbol of the cation first followed by the
anions.
• Write the respective charges
• Put them together using the crisscross method
Crisscross method- is done by writing the charge value
of the first ion as subscript of the second ion and vice
versa.
• Lastly, reduce the subscripts when possible into
lowest term
45. The previous examples are
called BINARY COMPOUNDS
since they involve only two
elements.
46. There are also compounds
which contain three different
elements. These are called
TERNARY COMPOUNDS. Most
of these compounds consists of
metallic cations and a
polyatomic anions.
47.
48. Example #1
Try to find out the chemical formula of the compound formed by the
reaction of sodium and a polyatomic ion
Na+ + OH- = NaOH
Note that the charge is understood to be one and is not
written anymore as a subscript in the formula.
49. Example #2
Try to find out the chemical formula of the compound formed by the
reaction of sodium and a polyatomic ion
Ca+2 + CO3
-2 = CaCO3
Subscript should be the smallest set of whole numbers possible. As you
can see in the formula, no subscripts were written since both contains new
atoms.
50. If there is more than one polyatomic ion in the formula, put the ion in
parenthesis and put the subscript after the parenthesis.
Example: Such that the reaction of aluminum (Al+3) to sulfate
(SO4
2-) would produce a compound with a chemical formula
Al2(SO4) 3.
57. A type of chemical bond in which do
not transfer elctrons but instead
they share electrons. This bond exist
between non-metals.
58. When two or more non-metallic
elements combine in a covalent
bonding, a MOLECULE is formed.
59. Gases like O2, H2, F2, Cl2, Br2, and I2
always occur as diatomic molecule.
60. Example: Oxygen has eight electrons
with a configuration of 1s22s22p4 . It
has a valence electrons of 6.
61. Example: Let us consider a methane
molecule (CH4).
-Carbon has valence electrons and
therefore needs four more electrons
to achieve the eight stable structure.
-Hydrogen has valence electron of
one.
69. To name covalent or molecular
compounds, you have to name first the
first non-metal. The second non-metal
is named by changing its suffix with –
ide.
* One exception of using these prefixes
is that the first element in the formula
never uses the word mono.
70. No. of Atoms Prefix
1 Mono
2 Di
3 Tri
4 Tetra
5 Penta
6 Hexa
7 Hepta
8 Octa
9 Nona
10 Deca
Prefixes for Naming Covalent Compounds