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 → Elements, Compounds, and Mixtures ↓


Difference Between Compounds and Mixtures


Understanding the difference between compounds and mixtures is an important part of chemistry. Both compounds and mixtures involve the combination of substances, but they differ significantly in terms of structure, properties, and methods of separation. In this explanation, we will explore their differences with the help of examples, simple language, and visual representations.

Basic definitions

First, let's define some key terms.

Elements

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Each element is made up of only one type of atom. For example, oxygen (O), hydrogen (H), and carbon (C) are all elements.

Compounds

A compound is a substance that is formed by two or more different elements being chemically bonded together. Water (H2O) is an example of a compound because it has two hydrogen atoms bonded to one oxygen atom. Compounds have a definite structure and unique properties that are different from the elements that make them up.

Mixture

A mixture is a combination of two or more substances that are not chemically bonded. Each substance in the mixture retains its own properties. Mixtures can be homogeneous (same composition) or heterogeneous (unequal composition). An example of a mixture is a salad, which might contain lettuce, tomatoes, cucumbers, and dressing.

Main Differences Between Compounds and Mixtures

Composition

Compounds have a fixed and stable composition. This means that the ratio of elements in a compound is always the same. For example, the ratio of hydrogen and oxygen in water (H2O) remains constant at 2:1.

On the other hand, mixtures do not have any fixed composition. The components of a mixture may be present in any proportion. For example, a fruit salad may contain varying quantities of different fruits depending on preference.

Visual example: water vs. salad

H Hey

The circles represent the atoms in a water molecule. The definite proportions and chemical bonds make up the compound (H2O). In contrast, a salad consists of separate ingredients that are simply mixed and not combined.

Property

Compounds have unique chemical and physical properties that differ from the elements that make them up. For example, sodium (Na) is a highly reactive metal, and chlorine (Cl) is a poisonous gas. However, when chemically combined, they form sodium chloride (NaCl), which is common table salt, a safe compound.

Mixtures do not have unique properties; instead, they exhibit the properties of the individual substances present within them. If you mix sand and salt, the resulting mixture will show the properties of both sand and salt independently.

Visual example: sodium chloride vs. sand-salt mixture

sodium chloride

On the left, sodium chloride is depicted as well-mixed and structured crystals. On the right, sand and salt particles retain their own properties within the mixture and are not chemically bonded.

Separation

Chemical reactions are needed to separate compounds into individual elements or simpler compounds. For example, a process called electrolysis is used to separate water into hydrogen and oxygen.

Mixtures can be separated by physical methods. For example, a mixture of iron filings and sulfur can be separated using a magnet so that the iron separates from the sulfur.

Visual Example: Electrolysis vs. Magnet Separation

Magnet

The electrolysis process on the left requires electrical energy to break water into hydrogen and oxygen gases. On the right, a magnet separates a mixture of iron filings, showing the physical method of separation.

Jet

Because the elements in a compound are chemically bonded, they usually do not retain their individual reactivity. The compound usually exhibits a new reactivity. For example, hydrogen is highly flammable and oxygen aids combustion, but water can extinguish a fire.

In a mixture, each component maintains its reactivity. If you mix iron filings and sulfur and burn the mixture, they react to form a compound called iron sulfide (FeS), which shows how the components of a mixture can react if they aren't yet chemically bonded.

Visual Example: Water vs. Iron-Sulfur Reactions

H2O Phase

Water, which is composed of individually reactive elements, acts as a new substance with its own properties, while iron and sulfur can also react to form a new compound when mixed.

Other characteristics

- Compounds are pure substances that have the same structure and properties. For example, every sample of pure water has the same properties because it is a compound.

- Mixtures are not considered pure substances. Each sample may have different composition, leading to different properties. An air sample may contain varying amounts of nitrogen, oxygen, and other gases depending on the environment.

Let's look at air as an example, which is a mixture of gases, primarily nitrogen and oxygen, but also containing argon, carbon dioxide, water vapor and other substances. Its composition may vary slightly from place to place or from time to time.

Conclusion

In conclusion, the main difference between compounds and mixtures lies in their structure, properties, methods of separation, and reaction tendencies. Compounds are composed of chemically bonded elements that have definite proportions and unique properties, requiring chemical reactions to separate them. Mixtures, however, consist of physically mixed substances that retain their original properties and can be separated by physical means. Understanding these differences is important in the study of chemistry and it helps us understand how substances interact in the natural world.


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Difference Between Compounds and Mixtures

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