Covalent Bond Interim Review
1. Covalent Bond is formed when elements cannot lose or gain electron
2. A Covalent Bond is formed by equal haring of the Valence electrons
3. Covalent bond is generally formed between nonmetals.
4. Atoms of the same element can form covalent bond. For example all the Diatomic
Elements are formed by covalent bond.
The diatomic elements are: Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine,
Iodine, and Astatine,
5. Covalent bond can vary in strength depending on whether the bond is single, double,
or triple;
a triple bond is stronger than a double bond, and a double bond is stronger than a
single bond.
6. Remember that always valence electrons are shared in covalent bonding.
7. We use the electronic dot structure to explain covalent bonding.
8. Electronegativity determines whether the covalent bond formed is a Pure Covalent
Bond or a Polar Covalent Bond.
9. A Pure covalent bond is formed when the electronegativity values between the atoms
is zero or less than 0.5
10. A polar covalent bond is formed when the electronegativity difference between the
atoms is between 0.5 and 1.6.
11. In the Periodic Table, the Electronegativity increases as you move from Left
to Right and it decreases as you move from top to bottom.
Daily Formative Assessment: Fill in the blanks
1. Covalent Bond is formed when elements cannot ------- or -------electron
2. A Covalent Bond is formed by --------- ---------- of the Valence electrons
3. Covalent bond is generally formed between --------------------.
4. ---------- of the ------- ------------ can form covalent bond. For example all the ----------
--- --------------- are formed by covalent bond.
The diatomic elements are: -----------------------------------------------------------------------
--------------------------------------------------------------------------------------
5. Covalent bond can vary in ---------- depending on whether the bond is single, -------
---------, or --------------; a ---------- bond is stronger than a -------- bond, and a ---------
- bond is stronger than a ----------- bond.
6. Remember that always valence electrons are --------- in covalent bonding.
7. We use the --------------- -------- ------------ to explain covalent bonding.
8. -------------------- determines whether the covalent bond formed is a -------- Covalent
Bond or a ------------- Covalent Bond.
9. A ------- covalent bond is formed when the electronegativity values between the
atoms is --------- or less than -------.
10. A -------- covalent bond is formed when the electronegativity difference between
the atoms is between ------- and ---------.
11. In the Periodic Table, the Electronegativity ------------------- as you move from Left to
Right and it -------------------------- as you move from top to bottom.
Properties of Covalent Compounds
Insoluble or very slightly soluble in
water
Slightly Higher Melting Point
Slightly Higher Boiling Point
Somewhat higher vapor pressure
Mostly Liquids or gas or vapors;
some or very low melting waxy
substances.
Mostly Liquids and some are semisolids
like cheese. Rarely, some are gases like
carbon dioxide.
Do not conduct electricity
Do not conduct electricity by
themselves, and can conduct electricity
when dissolved in water.
Examples:
Butter, camphor, Iodine, Wax,
Hydrogen, Oxygen, Nitrogen
Examples
Cheese, Carbon dioxide, Water, Alcohol,
pure vinegar
Cheese has a lot of intermolecular forces because it is a protein; butter has no
strong intermolecular forces because it is a fat.
Daily Formative Assessment
Take Covalent Bonding Quiz at Softschools Chemistry Quiz: Chemical
Bonding: II Covalent Bonding
On a Separate sheet of paper draw Polar covalent bond in Hydrogen
Chloride and water.
Intermolecular Forces Determine Melting and Boiling Points
Pure covalent molecules are internally very strongly bonded to each other
atom because of equal sharing of electrons. It is because of this strong
internal bonding, covalent molecules tend to behave in isolated way and have
weak connections to other molecules. Therefore, they need very little energy
to move and show low melting and boiling points.
Polar covalent molecules are dipoles and therefore they tend to have strong
intermolecular forces – the positive pole of one molecule can attract the
negative pole of another molecule and they tend to stay together. We have to
supply some energy to separate the molecules and make them move.
Therefore, polar covalent molecules have higher melting and boiling points
tahtn the pure covalent compounds.