Metallic Bonding, Vander-Walls forces and Hydrogen bonds

CONTENT

• Properties, Factors affecting the formation of metals
• Inter molecular bonding
• Vander-walls forces and hydrogen bonds
• Composition and Uses.

Metallic Bonding

The atoms of metals are held together in crystal lattice by metallic bonds

Properties

1. they are good conductors of electricity and heat
2. high melting and boiling points
3. they are malleable and ductile
4. they ionize by loosing electrons

Factors affecting the formation of metal strength

The Valence Electrons

Intermolecular Bonding

This is the type of chemical bonding which can be found in some molecular solid. Examples of intermolecular forces are

1. vander walls forces
2. Hydrogen force/bond

Vander Waal Forces: this is the  weak attractive forces that exist between the molecule.

Importance of  Vander waal forces

1. it is important in the liquefaction of gases
2. it is used in the formation of molecular lattices like iodine and naphthalene crystals.

EVALUATION

1. State the properties of the following bonds.

a. metallic bond            b. Vander waal

2. Give the diagram of a named metallic element (bonding diagram)

Hydrogen Bonding

Hydrogen bonding occur when hydrogen is covalently bonded with strongly electronegative element e.g nitrogen, fluorine, oxygen.

These electronegative elements pall the shared pair of electrons in the covalent bonds toward themselves.  Thus it results in dipole where the hydrogen is positive and the electronegative element is negative.

An electrostatic attraction set up when the positive pole of one molecule attract the negative pole of another molecule.

NB: The attractive force that exist between the two poles is called hydrogen bond.

Example of hydrogen bond

1. Hydrogen fluoride molecules

• Water molecules (ice crystal)

NB: There is covalent bond in a molecule of water while hydrogen bond is formed in molecules of water.

Use

It helps in the formation of water, alkanols and some organic acid molecules

GENERAL EVALUATION

1. Use diagram to differentiate between a molecule of water and molecules of water
2. State the molecules of a substance with strongest hydrogen bond.
3. Explain simple cubic structure

READING ASSIGNMENT

New School Chemistry by O.Y Ababio pg 294-298

WEEKEND ASSIGNMENT

1. An example of intermolecular bonding is (a) Vander wall (b) metallic (c) ionic (d) covalent
2. Both metallic substance and electrovalent compound are similar because (a) Both dissolve readily in water. (b) they have low melting point. (c) they can conduct electricity. (d) they have low boiling point.
3. The dotted line in an intermolecular bond stands for ____ (a) oxygen (b) hydrogen bond (c) ionic bond (d) covalent bond
4. Vander Wall force of attraction can be grouped as (a) Strongest force (b) hydrogen bond

(c) weakest force (d) ionic bond.

5. Metallic bond can easily be identified by the presence of (a) positive charge              (b) negative charge            (c) neutral charge (d) double bonds.

THEORY

1. State the type of chemical bond found in the following substances
2. Magnesium
3. Sodium chloride
4. Ammonium chloride
5. Molecules of hydrogen fluoride
6. A molecule of hydrogen
7. State four properties of the following  chemical bonds:
8. Electrovalent bond
9. covalent bond
10. dative bond
11. hydrogen bond
12. metallic bond