SPM Chemistry Form 4 (Periodic Table Of Elements) Chapter 4 - Part 2 Complete Revision

Summary

This video lesson, led by Teacher Daisy, covers key topics from Form Four Chemistry Chapter 4, focusing on the periodic table. It explores elements in Group 18 (noble gases) and Group 1 (alkali metals). The lesson discusses the physical and chemical properties of noble gases, their uses, and their stable electron arrangements. It also explains the reactivity and characteristics of alkali metals, including their reactions with water, oxygen, and chlorine. The content is presented in a clear, step-by-step manner to help students grasp these important concepts.

Takeaways

• 🧪 Group 18 elements, also known as noble gases, are monoatomic gases under room conditions, such as Helium (He), Neon (Ne), Argon (Ar), and others.
• 💨 Noble gases are colorless, odorless, and insoluble in water, and do not conduct heat or electricity.
• 🌡️ Boiling point and density of noble gases increase as you move down Group 18 due to stronger Van der Waals forces.
• ⚗️ Chemically, noble gases are inert and have stable electron arrangements (duplet for Helium, octet for others).
• 🔋 Uses of noble gases include neon in advertisement lamps, argon in filament light bulbs and welding, and helium in weather balloons and scuba tanks.
• 🔬 Group 1 elements, known as alkali metals, include Lithium (Li), Sodium (Na), and Potassium (K). These metals exhibit metallic properties but are softer and have lower melting points compared to other metals.
• 🔪 Alkali metals are soft and can be cut with a knife. They have lower density, with some like lithium, sodium, and potassium floating on water.
• 🌡️ As you move down Group 1, the melting point, boiling point, and hardness decrease, while atomic size increases.
• 🔥 Alkali metals react actively with water, producing metal hydroxide and hydrogen gas, with reactivity increasing from lithium to potassium.
• ⚠️ Alkali metals are highly reactive with oxygen and chlorine, forming metal oxides or chlorides, with reactivity increasing down the group.

Q & A

What are Group 18 elements commonly known as?

Group 18 elements are commonly known as noble gases.

Why are noble gases chemically inert?

Noble gases are chemically inert because they have a stable duplet or octet electron arrangement, meaning their outermost shell is fully occupied with electrons.

What happens to the boiling point of noble gases as you move down Group 18?

The boiling point of noble gases increases as you move down Group 18 because the Van der Waals forces of attraction between the atoms become stronger, requiring more heat energy to overcome.

What is the main use of argon in daily life?

Argon is primarily used as a filling gas for filament light bulbs to prevent the filament from burning and to reduce metal evaporation.

Why is helium used in scuba diving tanks?

Helium is used in scuba diving tanks because it is much less dense than air and has very low solubility, which prevents it from dissolving in the blood even at high pressures.

How does the atomic size of alkali metals change as you move down Group 1?

The atomic size of alkali metals increases as you move down Group 1 because the number of electron shells increases.

What happens to the reactivity of Group 1 elements with water as you move down the group?

The reactivity of Group 1 elements with water increases as you move down the group, with potassium being more reactive than sodium and lithium.

Why are alkali metals stored in paraffin oil?

Alkali metals are stored in paraffin oil to prevent them from reacting with oxygen and water vapor in the air, as they are highly reactive.

What type of solution is produced when alkali metals react with water?

When alkali metals react with water, they produce an alkaline metal hydroxide solution and hydrogen gas.

What is the trend in density of alkali metals as you move down Group 1?

The density of alkali metals increases as you move down Group 1.