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 → Acids, Bases and Salts ↓


Properties of bases


In chemistry, a base is a substance that can accept a hydrogen ion (proton) or, more commonly, donate a pair of valence electrons. Bases can be found in various forms, such as solids, liquids, and gases. Understanding the properties of bases is an important aspect of chemistry that helps us understand how substances react with each other.

Understanding pH and bases

The pH scale is a way to measure how acidic or alkaline a solution is. The scale ranges from 0 to 14, where 7 is considered neutral. A pH less than 7 indicates acidity, while a pH greater than 7 indicates alkali. Bases have the ability to neutralize acids. Here's a simple representation:

Acid < 7 < Neutral < 7 < Base

Visual example

0 Acid 3-6 7 Neutral 8-10 11 Base

General properties of bases

Bases have several special properties that make them unique. Here we will discuss several important properties of bases:

Taste

One of the most common properties of bases is their bitter taste. However, it is important not to taste bases in a laboratory setting because they can be harmful. Many everyday items, such as baking soda (used in cooking), have a slightly bitter taste, which is a characteristic of bases.

Slippery feel

Alkalis often feel soapy or slippery to the touch. This is because alkalis react with fatty acids on our skin to form soap. This property is useful in cleaning products. For example, soaps and detergents are basic compounds that can dissolve oil and grease.

Impact on indicators

Indicators are substances that change color in the presence of an acid or base. Bases usually turn red litmus paper blue. This change in color helps to identify the presence of base. Here's what happens with common indicators:

  • Red litmus paper turns blue.
  • Phenolphthalein turns pink in alkaline solution.
  • Methyl orange turns yellow under basic conditions.

Chemical reactivity of bases

Bases react with acids in a process called neutralization. When acids and bases react, they form salt and water. Here is a general equation for neutralization:

    Acid + Base → Salt + Water

For example, when hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), sodium chloride (NaCl) and water (H 2 O) are formed:

    HCl + NaOH → NaCl + H 2 O

This reaction is exothermic, that is, it releases heat energy.

Types of bases

Bases are mainly classified into two types: strong bases and weak bases.

Strong base

Strong bases are substances that dissociate completely in water to release hydroxide ions (OH -). Here are some examples:

  • Sodium hydroxide (NaOH)
  • Potassium hydroxide (KOH)
  • Calcium hydroxide (Ca(OH) 2)

Weak base

Weak bases do not completely dissociate in water and therefore do not release hydroxide ions effectively. Some common weak bases include:

  • Ammonia (NH 3)
  • Sodium Bicarbonate (NaHCO 3)

Applications of bases

Bases are widely used in various industries and daily applications. Here are some examples:

Cleaning products

Many cleaning products are basic in nature. They are effective at breaking down grease and oil, making them excellent for household cleaning tasks.

Cooking and baking

Baking soda, a weak base, is used as a leavening agent in cooking. It reacts with the acidic components in the batter to release carbon dioxide gas, which helps the dough and batter to rise.

Medicine

Bases are used in medicines to reduce symptoms of indigestion and heartburn. Antacids, which are bases, work by neutralizing excess acid in the stomach.

Security and operation of bases

Although bases have many useful applications, they can also be dangerous if not handled properly. It is important to follow safety guidelines to avoid harm:

  • Always wear gloves and safety glasses when working on solid grounds.
  • Avoid swallowing or inhaling alkalis, as they can be corrosive.
  • In case of skin contact, wash affected area with plenty of water.

Conclusion

Understanding the properties of bases provides valuable information about their behavior and their use in various fields. From their bitter taste to their chemical reactivity, bases are an integral part of both the natural world and man-made products. It is important to recognize both their benefits and hazards in order to use them safely and effectively in various applications.


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Properties of Acids
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Properties of bases

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