SPM Chemistry (KSSM) Paper 1

01 Introduction to Chemistry
1.1 Chemistry and Its Importance
1 Lesson
1.1.1 Chemistry and Its Importance
1.2 Scientific Investigation
1 Lesson
1.2.1 Scientific Investigation
02 The Structure of Atoms
2.1 The Basic Concept of Matter
2 Lessons
2.1.1 The Particle Theory of Matter
2.1.2 The Three States of Matter
2.2 The History of Development of the Atomic Model
1 Lesson
2.2.1 The History of Development of the Atomic Model
2.3 The Structure of Atom
2 Lessons
2.3.1 The Structure of Atom
2.3.2 Electrons Arrangement in Atom
2.4 Isotopes and Their Uses
1 Lesson
2.4.1 Isotopes and Their Uses
2.5 The Structure of Atom - Practices
03 Concept of Mole, Formulae and Equations
3.1 Relative Atomic Mass and Relative Molecular Mass
1 Lesson
3.1.1 Relative Atomic Mass and Relative Molecular Mass
3.2 Concept of Mole
3 Lessons
3.2.1 Concept of Mole
3.2.2 Number of Mole and Mass
3.2.3 Number of Mole and Volume of Gases
3.3 Chemical Formulae
2 Lessons
3.3.1 Chemical Formulae
3.3.2 Formula of Ionic Compounds and Molecule
3.4 Chemical Equations
1 Lesson
3.4.1 Chemical Equations
3.5 Chemical Formulae and Equations - Practices (Coming Soon)
04 Periodic Table of Elements
4.1 The Development of Periodic Table
1 Lesson
4.1.1 Development of Periodic Table
4.2 Arrangement of Element in Periodic Table
1 Lesson
4.2.1 Arrangement of Electrons in Periodic Table
4.3 Group 18 Elements
1 Lesson
4.3.1 Group 18 Elements
4.4 Group 1 Elements
2 Lessons
4.4.1 Group 1 Elements
4.4.2 Chemical Properties of Group 1 Elements
4.5 Group 17 Elements
2 Lessons
4.5.1 Group 17 Elements
4.5.2 Chemical Properties of Group 17 Elements
4.6 Elements in Period 3
1 Lesson
4.6.1 Elements in Period 3
4.7 Transition Elements
1 Lesson
4.7.1 The Transition Elements
4.8 Periodic Table - Practices (Coming Soon)
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4.4.2 Chemical Properties of Group 1 Elements

SPM Chemistry (KSSM) Paper 1 4.4 Group 1 Elements 4.4.2 Chemical Properties of Group 1 Elements
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Chemical Properties of Alkali Metals


  1. Group 1 metals are very reactive metals.
  2. They all show the same chemical properties.
  3. They can react with water and non-metal such as oxygen and chlorine to form a new compound.
  4. The table to the right shows the electron arrangement of all the Group 1 metals. All the atoms of Group 1 metal consist of 1 valence electron.
  5. When an alkali metal atoms react, it loses the valence electron to form a positively charged ion. 

Example:

    1. Li → Li⁺ + e
    2. Na → Na⁺ + e
    3. K →  K⁺ + e

They tend to react mainly with non-metals to form ionic compounds.

Safety Precaution

  1. Alkali metals are very reactive.
  2. Therefore it must be kept in paraffin oil to prevent them from reacting with oxygen and water vapour in the air.
  3. We must avoid holding group 1 metals with bare hand because they may react with water on our hand.
  4. We must wear safety goggles and gloves during handling experiment involving group 1 metal.
 

Reaction of Alkali Metals with Chlorine

  1. All alkali metals react with chlorine gas to form white metal chlorides salt.
    Group 1 Metals + Chlorine Gas → Metal Chloride
  2. The metal chlorides salt formed is soluble in water to give a neutral solution of pH 7.
  3. The reactivity increases down the group from lithium, sodium to potassium.

Example:

Lithium + Chlorine

2Li + Cl2 → 2LiCl

Observation
Lithium burned slowly with a reddish flame . A white solid is produced.

Sodium + Chlorine

2Na + Cl2 → 2NaCl

Observation
Sodium burned brightly with a yellowish flame. A white solid is produced.

Potassium + Chlorine

2K + Cl2 → 2KCl

Observation
Potassium burned very brightly with a purplish flame. A white solid is produced.

Reaction of Alkali Metals with Oxygen

  1. Group 1 metals react with oxygen gas produces metal oxides. These metal oxides dissolve in water produces alkalis.
    Group 1 Metals + Oxygen Gas → Metal Oxide
  2. Lithium, sodium and potassium form white oxide powders after reacting with oxygen.
  3. The white powder is the oxide of lithium, sodium and potassium.
  4. When the white powder is dissolved in water, it produces a solution which turned red litmus paper blue. Which means, these oxides dissolve in water to form strong alkali.
  5. The reactivity increases down the group from lithium, sodium to potassium.

Example

Lithium + Oxygen

4Li + O2→ 2Li2O

Dissolve in water

Li2O + H2O → 2LiOH

Observation
Lithium burns with red flame and produces white powder immediately after reaction.

Sodium + Oxygen

4Na + O2→ 2Na2O

Dissolve in water

Na2O + H2O → 2NaOH

Observation
Sodium burned with bright yellow flame, forming white powder immediately after reaction.

Potassium + Oxygen

4K + O2→ 2K2O

Dissolve in water

K2O + H2O → 2KOH

Observation
Potassium burned with very bright purplish flame, forming white powder immediately after the reaction.

Reaction of Alkali Metals with Water

Group 1 metals react vigorously with water produces alkali and hydrogen gas

Group 1 Metals + Water → Alkali + Hydrogen gas

Common Observation

  1. Lithium, sodium or potassium floats and move around on the surface of the water and then dissolve in the water.
    Conclusion:
    Lithium, sodium and potassium are less dense than water.
  2. Colourless gas is released around the metal. The gas produces a “pop” sound when ignited with a lighted wooden splinter.
    Conclusion:
    The colourless flammable gas is hydrogen.
  3. The solution turns blue when it is tested with universal indicator.
    Conclusion:
    the solution produced is an alkali.

 

Lithium + Water

2Li + 2H2O → 2LiOH + H2

Observation
Lithium metal moves slowly on the surface of the water with ‘fizzing’ sound.

 

Sodium + Water

2Na + 2H2O → 2NaOH + H2

Observation
The lump of sodium moves swiftly on the surface of water with ‘fizzing’ sound

Potassium + Water

2K + 2H2O → 2KOH + H2

Observation
Potassium reacts violently with water, move very fast on the surface of water and burn with lilac flame.

Explaining the Reactivity Trend of the Alkali Metals

  1. When an alkali metal atom reacts, it loses its valence electron to form a positively charged ion.
    Example
    Li → Li+ + e
    Na → Na+ + e
    K → K+ + e
  2. As we go down the group from one element down to the next, the atomic radius gets bigger due to an extra filled electron shell.
  3. The valence electron is further and further from the nucleus. Thus the attraction force between the nucleus and the valence electron become weaker and weaker.
  4. This causes the valence electron is easier to be released to form an ion when the atom takes part in a reaction.
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