A brief discussion on Chemical Bonds for hyrogen bonding, metallic bonding and dative bonding. the formation of each bonding is illustrated by using the molecular formula which shows the electrons involved in the bonding.

1. CHEMICAL BONDS
Hydrogen bond, dative bond and metallic bond
XYLENE AR

2. HYDROGEN BOND
• Hydrogen bonding is the interaction between hydrogen atoms with atoms that
have high electronegativity such as nitrogen, oxygen and fluorine.
 Hydrogen bonds are also inter-molecular attractions that affect the physical
properties of materials namely 1) melting point & boiling point, 2) solubility
in water, 3) solubility in organic solvents and 4) electrical conductivity.
1) Melting point and boiling point
- depending on the strength of the attraction between the molecules.
- the presence of hydrogen bonds increases the melting point and boiling point.
- larger molecules have a higher Van der Waals attraction, therefore higher heat energy
is required to break the bond. This makes the melting point and boiling point high
 Molecular materials or covalent compounds have different types of
intermolecular attraction namely hydrogen bonds and Van der Waals forces.

3. H-O-H
HYDROGEN BOND
 An essential requirement for the formation of hydrogen bonds :
1) A hydrogen atom fused with an atom has high electronegativity properties.
2) Pair/s of lone electrons on the electronegative atom
Ammonia liquid
Hydrogen bond
Hydrogen fluoride
Lone pair of electrons
 For example :
H
H-N-H
Lone pair of electrons
Water molecule
H F Lone pair of electrons

4. HYDROGEN BOND
 2) Solubility in water
- the molecular substances must have the ability to form hydrogen bonds
- therefore, the molecular material is insoluble in water/ only slightly soluble
 An example of a slightly soluble molecular substance in water is ammonia.
Solubility is only 1% by forming ammonium ions.
Reversible equation : NH3 + H2O ⇌ NH4
+ + OH-
 Examples of water-soluble molecular substances are ethanol and sucrose

5. HYDROGEN BOND
 3) Solubility in organic solvents
- Solvents and solutes have a Van der Waals attraction between the molecules.
- It makes the molecular material soluble in organic solvents
 4) Electrical conductivity
- Electrical conduction occurs as a result of the movement of electrons in a
molecule, however, electrons cannot move properly because there is not
enough space between molecules in a solid or liquid.
- It makes the molecular material unable to conduct electricity.

6. DATIVE/ COVALENT COORDINATE BOND
• A dative/ coordinate bond is a type of covalent bond between
two atoms in which the two shared electrons come from only
one atom.
For example:
H
H N
H
Dative bond
H Cl
+
H
H N H
H
Cl
+
+
-
Ammonium ion
Ammoni
a
Hydrogen chloride Chloride ion

7. DATIVE/ COVALENT COORDINATE BOND
• A dative/ coordinate bond is a type of covalent bond between
two atoms in which the two shared electrons come from only
one atom.
 For example :
H O
H
Dative
bond
H Cl
+ H O H
H
Cl
+
+
-
Hydroxonium ion
Wate
r
Hydrogen chloride Chloride
ion

8. METALLIC BONDING
• Bonds formed between metal atoms
• The valence electrons of metal atoms are depleted to form an ocean of
electrons
• The electrostatic force between the ocean of electrons and positively
charged metal ions forms a metal bond
• Metals can conduct electricity because electrons in an ocean of
electrons can move freely and carry a charge.
+
+ + +
+
+
+ + +
+ + +
e-
e-
e-
e-
e-
e-
e-
e-
e-