Grade 7
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Scientific Method in Chemistry  1.5. Laboratory Safety Rules and Precautions  1.6. Common Laboratory Equipment and Their Uses  1.7. Units of measurement in chemistry
  2. Matter and its properties  2.1. Definition of Matter  2.2. Classification of matter  2.3. Properties of matter  2.3.1. Physical properties  2.3.2. Chemical properties  2.4. States of matter  2.4.1. Solid state  2.4.2. Fluid state  2.4.3. Gaseous state  2.4.4. Plasma and Bose–Einstein condensates  2.5. Changes in the states of matter  2.5.1. Melting and freezing  2.5.2. Evaporation and Condensation  2.5.3. Sublimation and deposition  2.6. Density and its applications  2.7. Diffusion and its importance
  3. Elements, Compounds, and Mixtures  3.1. Definition of the element  3.2. Classification of elements  3.3. Metals, Nonmetals and Metalloids  3.4. Noble gases and their properties  3.5. Introduction to the Periodic Table  3.6. Definition of Compound  3.7. Properties of Compounds  3.8. Introduction to Chemical Formulas  3.9. Definition of Mixture  3.10. Types of mixtures  3.10.1. Homogeneous mixture  3.10.2. Heterogeneous mixtures  3.11. Difference Between Compounds and Mixtures  3.12. Solutions, Colloids and Suspensions
  4. Separation of mixtures  4.1. Need for separation of mixtures  4.2. Separation methods  4.2.1. Filtration  4.2.2. Sedimentation and decantation  4.2.3. Evaporation  4.2.4. Crystallization  4.2.5. Distillation  4.2.6. Chromatography  4.2.7. Magnetic Separation  4.2.8. Centrifugation
  5. Atomic Structure  5.1. Introduction to Atoms  5.2. Structure of the atom  5.2.1. Nucleus and electron cloud  5.3. Subatomic particles  5.3.1. Proton  5.3.2. Neutron  5.3.3. Electrons  5.4. Atomic number and mass number  5.5. Isotopes and their uses  5.6. Ions and ion formation
  6. Periodic table  6.1. Introduction to the Periodic Table  6.2. Groups and periods  6.3. Trends in the Periodic Table  6.3.1. Atomic Size  6.3.2. Metallic and non-metallic character  6.3.3. Electronegativity  6.3.4. Reactivity of the elements  6.4. Alkali metals and their properties
  7. Chemical bond  7.1. Why do atoms form bonds?  7.2. Types of chemical bonds  7.2.1. Ionic bond  7.2.2. Covalent bond  7.2.3. Metal Bond  7.3. Properties of Ionic and Covalent Compounds  7.4. Intermolecular forces
  8. Chemical reactions  8.1. Introduction to Chemical Reactions  8.2. Signs of a chemical reaction  8.3. Types of Chemical Reactions  8.3.1. Combination Reactions  8.3.2. Decomposition reactions  8.3.3. Displacement reactions  8.3.4. Double displacement reactions  8.3.5. Combustion reactions  8.4. Law of conservation of mass  8.5. Balancing simple chemical equations
  9. Acids, Bases and Salts  9.1. Definition of Acid and Base  9.2. Properties of Acids  9.3. Properties of bases  9.4. pH Scale and Indicators  9.5. Neutralization reactions  9.6. Common Acids and Bases in Everyday Life  9.7. Preparation and use of salts  9.8. Strong and weak acids and bases
  10. Solutions and Solubility  10.1. Definition of Solution  10.2. Components of the solution  10.2.1. Solvent  10.2.2. solute  10.3. Factors Affecting Solubility  10.4. Concentration of solutions  10.5. Saturated and unsaturated solutions  10.6. Colloids and suspensions  10.7. Solubility curve and its interpretation
  11. Air and atmosphere  11.1. Composition of air  11.2. Properties of gases in the air  11.3. Importance of Oxygen and Carbon Dioxide  11.4. Air pollution and its effects  11.5. Greenhouse effect and global warming  11.6. Ways to reduce air pollution  11.7. Ozone layer and its importance
  12. Water and its importance  12.1. Properties of Water  12.2. Water as the universal solvent  12.3. Importance of water for life  12.4. Water pollution and its effects  12.5. Water Purification  12.5.1. Filtration  12.5.2. boil  12.5.3. Chlorination in water purification  12.5.4. reverse osmosis  12.6. Hard and soft water  12.7. Water cycle and its importance
  13. Fuel and energy  13.1. Types of fuel  13.1.1. Fossil fuels  13.1.2. Renewable energy sources  13.2. Combustion and energy release  13.3. Global warming and its effects  13.4. Alternative sources of energy  13.5. Ways to conserve energy
  14. Metals and Nonmetals  14.1. Physical and chemical properties of metals  14.2. Physical and Chemical Properties of Non-Metals  14.3. Difference Between Metals and Nonmetals  14.4. Uses of metals and nonmetals  14.5. Corrosion of metals and its prevention  14.6. Alloys and their importance
  15. Plastics and polymers  15.1. Natural and synthetic polymers  15.2. Properties of plastics  15.3. Biodegradable and Non-Biodegradable Plastics  15.4. Environmental impact of plastic  15.5. Recycling and waste management in plastics and polymers  15.6. Daily Uses of Polymers
  16. Introduction to Organic Chemistry  16.1. Basic definitions of organic chemistry  16.2. Carbon Compounds in Daily Life  16.3. Hydrocarbons  16.4. Simple functional groups (alcohols and carboxylic acids)  16.5. Importance of organic compounds in industry

Grade 7 → Periodic table ↓


Alkali metals and their properties


Alkali metals are a group of elements in the periodic table that have similar properties. They are very reactive and are found in group 1 of the periodic table. Alkali metals include:

  • Lithium (Li)
  • Sodium (Na)
  • Potassium (K)
  • Rubidium (Rb)
  • Caesium (Cs)
  • Francium (Fr)

Alkali metals are so reactive that they are not found freely in nature. Instead, they are found in compounds. Let's take a closer look at the properties and uses of each of these metals.

Overview of properties

All alkali metals have one electron in their outermost shell, which makes them highly reactive. They easily lose this electron to achieve a stable electron configuration. Here are some shared properties:

  • Physical Properties: Soft, can be cut with a knife; shiny surface when freshly cut.
  • Chemical Properties: Highly reactive, especially with water; forms alkaline solutions (alkalis).
  • Density: Low density; some are less dense than water.
  • Melting Point and Boiling Point: Lower melting point and boiling point than most other metals.

Visualisation of alkali metals

Took No K RB C

This diagram represents the first five alkali metals on the periodic table using colored blocks. Each block represents an alkali metal from lithium to cesium, arranged from left to right.

Understanding reactivity

Alkali metals are known for their strong reactions, especially with water. Reaction with water produces hydrogen gas and the metal hydroxide, which is a base. Let's look at an example with sodium:

2 Na (s) + 2 H 2 O (l) → 2 NaOH (aq) + H 2 (g)

In this chemical equation, Na represents sodium, H 2 O is water, NaOH is sodium hydroxide, and H 2 is hydrogen gas. The reaction is exothermic, which means it releases heat, sometimes causing the hydrogen gas to ignite.

Reactivity tendency

The reactivity of alkali metals increases going down the group. This means that caesium is more reactive than lithium. This trend is due to the increase in atomic size, which makes it easier for the outer electron to be lost.

Took No K RB C Reactivity ↑

This graph shows the increase in reactivity of the alkali metals as we move from lithium (Li) to caesium (Cs).

Important alkali metals and their uses

Lithium (Li)

Lithium is the lightest metal and is used in batteries of electronic devices such as mobile phones and laptops. Lithium compounds are also used in the treatment of mood disorders. Although it reacts with water, it is less reactive than other alkali metals.

Sodium (Na)

Sodium is essential in our daily lives. The most common compound, sodium chloride (NaCl), is ordinary table salt. Sodium is also used in street lighting. When you see yellow street lights, sodium vapor lamps may be working.

Potassium (K)

Potassium is very important for plants and is found in fertilizers because of its role in plant growth. It is also an important nutrient for humans, found in foods such as bananas and potatoes, contributing to biological functions such as heart health.

Rubidium (Rb) and Caesium (Cs)

Rubidium and caesium are used in a variety of industries. Caesium is used in atomic clocks, the most accurate time-measuring devices, while both elements are used in research and special equipment.

Francium (Fr)

Francium is extremely rare and highly radioactive. It has no significant commercial applications because of its scarcity and radioactivity. Its overall properties have been less well studied than those of the other alkali metals.

More chemical reactions

Let's look at another example reaction with potassium. Like sodium, potassium also reacts energetically with water:

2 K (s) + 2 H 2 O (l) → 2 KOH (aq) + H 2 (g)

This equation shows potassium reacting with water to form potassium hydroxide (KOH) and hydrogen gas (H 2). This reaction is faster and more vigorous than the reaction of sodium with water.

Safety and precautions

Because of their reactivity, caution is required when handling alkali metals. They must be stored under oil to prevent reaction with moisture in the air. In laboratory settings, small quantities are used to prevent dangerous situations.

Conclusion

Alkali metals have unique and fascinating properties. Their reactivity increases as you go down the group in the periodic table. They play important roles in both industrial applications and biological functions. Organizations working with these metals must follow strict safety guidelines to manage their reactive nature.


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