Grade 8
  1. Introduction to Chemistry  1.1. Nature and scope of chemistry  1.2. Importance of chemistry in daily life  1.3. Chemistry and its relation with other sciences  1.4. The role of chemistry in industry, medicine and the environment  1.5. Scientific investigation and experimental methods in chemistry
  2. Matter and its properties  2.1. Definition and classification of matter  2.2. Physical and chemical properties of matter  2.3. Law of conservation of matter  2.4. Extensive and Intensive Properties of Matter  2.5. Kinetic molecular theory of matter  2.6. States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates  2.7. Changes in state and energy are involved  2.8. Diffusion and Brownian motion
  3. Elements, Compounds, and Mixtures  3.1. Definition and differences between elements, compounds, and mixtures  3.2. Atomic Structure and Atomic Number  3.3. Chemical symbols and formulas  3.4. Trends in the Periodic Table (Groups and Periods)  3.5. Classification of Elements: Metals, Nonmetals and Metalloids  3.6. Rare Earth Elements and Transition Metals  3.7. Types of mixtures: homogeneous and heterogeneous  3.8. Separation of Mixtures Using Physical and Chemical Methods
  4. Separation Techniques  4.1. Filtration, Sedimentation and Decantation  4.2. Evaporation and crystallization  4.3. Distillation and Fractional Distillation  4.4. Chromatography and its applications  4.5. Sublimation in the purification of compounds  4.6. The role of centrifugation in biochemical processes
  5. Atomic Structure  5.1. Dalton's atomic theory  5.2. Structure of the atom: protons, neutrons and electrons  5.3. Bohr's atomic model  5.4. Introduction to Quantum Mechanical Model  5.5. Electron Configuration and Energy Levels  5.6. Excitation and emission spectra  5.7. Isotopes and their applications
  6. Periodic Table and Chemical Trends  6.1. History and Development of the Periodic Table  6.2. Modern periodic law  6.3. Periodicity and trends in atomic and ionic sizes  6.4. Ionization Energy, Electron Affinity and Electronegativity  6.5. Introduction to Lanthanides and Actinides  6.6. Application of periodic trends in chemistry
  7. Chemical Bonding and Molecular Structure  7.1. Types of chemical bonds: ionic, covalent and metallic bonds  7.3. Polar and Nonpolar Molecules  7.4. Hydrogen bonding and its applications  7.5. Intermolecular forces: dipole-dipole, London dispersion force
  8. Chemical Reactions and Stoichiometry  8.1. Chemical Equations and Balance  8.2. Types of Chemical Reactions: Combination, Decomposition, Displacement and Redox  8.3. Introduction to stoichiometry and the mole concept  8.4. Limiting reactant in chemical equations  8.5. Reaction rate, catalyst, and factors affecting reaction rate
  9. Acids, Bases and Salts  9.1. Definition and Properties of Acids and Bases  9.2. Strong vs. Weak Acids and Bases  9.3. pH Scale and pH Calculation  9.4. Neutralization reactions  9.5. Buffer solutions and their importance  9.6. Applications of Acids, Bases and Salts in Daily Life
  10. Solutions and Solubility  10.1. Definition of Solution, Solute, and Solvent  10.2. Factors Affecting Solubility  10.3. Concentration units: molarity and molality  10.4. Saturated, unsaturated and supersaturated solutions  10.5. Concept of osmosis and reverse osmosis  10.6. Concentrative properties of solutions
  11. Gases and Gas Laws  11.1. Properties of gases  11.2. Introduction to Ideal and Real Gases  11.3. Boyle's Law, Charles' Law and Avogadro's Law  11.4. Ideal Gas Equation and Its Applications  11.5. Application of Gas Laws in Real Life
  12. Thermochemistry and energy transformation  12.1. Energy in Chemical Reactions  12.2. Exothermic vs. Endothermic Reactions  12.3. Heat and Enthalpy Changes  12.4. Calorimetry and heat transfer in reactions
  13. Metals and Nonmetals  13.1. Physical and Chemical Properties of Metals and Nonmetals  13.2. Reactivity Series of Metals  13.3. Corrosion and its prevention  13.4. Extraction of metals from ores  13.5. Uses of metals and non-metals in daily life
  14. Introduction to Organic Chemistry  14.1. Characteristics of carbon and organic compounds  14.2. Functional groups and their importance  14.3. Simple Hydrocarbons: Alkenes, Alkenes and Alkynes  14.4. Isomerism in organic compounds  14.5. Introduction to polymers and their uses
  15. Environmental Chemistry and Sustainability  15.1. Green Chemistry Principles  15.2. Effects of Chemical Pollution on Ecosystems  15.3. Acid rain and its effects  15.4. Ozone layer depletion and global warming  15.5. Waste Management and Recycling in Chemistry

Grade 8 → Matter and its properties ↓


States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates


Matter is everything around us. It is everything that has mass and occupies space. Matter is made up of atoms and molecules. These particles are always in motion. How these particles move and interact with each other determines the state of matter.

The common states of matter are solid, liquid, and gas. However, under certain conditions, matter can also exist in other states such as plasma and Bose-Einstein condensate.

Solid

A solid is a state of matter in which the particles are attached to each other in an orderly manner. The particles do not move freely but vibrate in place. This gives a solid a definite shape and volume.

Visual example: In the box grid above, each circle represents a particle. Notice how the particles are closely packed in a regular pattern.

Example:

  • A book.
  • A piece of ice.
  • A table.

Liquid

A liquid is a state of matter in which the particles are close together but not in any fixed position. They can slide over each other, allowing a liquid to take the shape of its container while still maintaining a constant volume.

Visual example: In the top part of the box, the circles are packed close to each other but randomly, indicating that the particles are sliding past each other.

Example:

  • Water.
  • Juice.
  • Oil.

Gas

A gas is a state of matter in which the particles are far apart and move around freely. This high energy and freedom allows gases to fill the shape and volume of their container.

Visual example: In the box above, there are circles spread all around, showing the random and free motion of the particles.

Example:

  • Air.
  • Helium in balloons.
  • Steam.

Plasma

Plasma is a state of matter where gases remain active as long as the atomic electrons are no longer attached to a particular atomic nucleus. It is an ionized gas consisting of positive ions and free electrons.

Plasmas occur naturally in the Sun and other stars, where temperatures are high enough for this state to persist. They are also found in lightning or can be created in a laboratory environment.

Visual example: In the box above, charged particles (ions) are moving freely, demonstrating plasma behaviour.

Example:

  • Sun and other stars.
  • Neon lights.
  • Lightning.

Bose–Einstein condensates

Bose-Einstein condensates (BECs) form when a gas of bosons is cooled to temperatures very close to absolute zero (0 Kelvin, or -273.15 °C). Under such conditions, a large number of atoms "condense" into the lowest quantum state of the external potential, making quantum effects apparent on a macroscopic scale.

In a BEC the atoms move very slowly and behave as if they were a single atom. This is a state of matter where particles act together, producing quantum phenomena on a very large scale.

Visual example: The group at the center represents particles behaving like a single quantum entity.

Example:

  • Supercooled rubidium gas.

Transitions between states

Matter can change from one state to another through physical processes. These changes often occur due to the addition or removal of energy, usually in the form of heat. Here are some common changes:

  • Melting: The process of a solid changing into a liquid. This occurs when heat is added to a solid, causing the particles to vibrate more rapidly until they are released from their fixed positions. Example: Ice melting into water.
  • Freezing: The process of a liquid changing into a solid. This occurs when heat is removed, causing the particles to slow down and become locked in a stationary position. Example: Water freezing into ice.
  • Vaporization: The process of a liquid changing into a gas. This can happen through boiling, where heat causes gas bubbles to form within the liquid, or through evaporation, where molecules on the surface of the liquid gain enough energy to escape into the air. Example: Water boiling into steam.
  • Condensation: The process of changing a gas into a liquid. It occurs when gas particles lose energy and come closer together to form a liquid. Example: Water vapor in the air condenses as dew on a cold surface.
  • Sublimation: The process of changing a solid directly into a gas without going through the liquid state. Example: Dry ice (solid carbon dioxide) changing directly into carbon dioxide gas.
  • Deposition: The process of changing a gas directly into a solid. This happens without going through the liquid state. Example: Frost forming on cold surfaces.

Matter and its properties

The study of matter also includes understanding its properties. These properties help scientists understand the behavior of matter under different conditions.

Physical properties

Physical properties of matter can be observed or measured without changing its identity. These include:

  • Color: Hue, saturation, and brightness are the way a material reflects light.
  • Density: The mass of a substance per unit volume. For example, water has a density of about 1 gram per cubic centimeter (g/cm3).
  • Volume: The space occupied by a substance.
  • Boiling point and melting point: The temperature at which a substance changes its state.

Chemical properties

Chemical properties describe a substance's ability to undergo chemical changes or reactions based on its structure. These include:

  • Reactivity: The tendency of a substance to react chemically with other substances.
  • Flammability: The ability of a substance to burn in the presence of oxygen.
  • Acidity or alkalinity (pH): This is a measure of how acidic or alkaline a substance is. It ranges from 0 (strongly acidic) to 14 (strongly alkaline).

Examples of change of matter

Let us consider water as an extraordinary substance that can easily transform between its states.

Solid (Ice) → Liquid (Water) → Gas (Steam)

Temperature transfer (gain or loss of heat) causes these changes:
The ice melt turned into water.
Above the boiling point water evaporates into steam.
On cooling, the steam condenses back into water.
When water freezes below the freezing point it becomes ice.

In conclusion, understanding the states of matter is fundamental in knowing how substances interact in the world around us. Through observation and measurement of their physical and chemical properties, we gain information about the behavior and interaction of different substances in various state transitions.


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States of matter: solids, liquids, gases, plasmas, and Bose-Einstein condensates

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