14.0     INTRODUCTION

MOLECULAR NATURE OF MATTER: All matter is composed of tiny particles called atoms, which are the fundamental building blocks of matter.

• Molecules are formed when two or more atoms bond together, either of the same element or different elements.
• Atoms: Atoms consist of a nucleus (containing protons and neutrons) surrounded by electrons.
• Molecules: Molecules can be simple (like O2) or complex (like C6H12O6) and can exist in different states (solid, liquid, gas).
• Molecular Theory: Molecular theory explains the behaviour of matter based on the motion and interaction of molecules.

To get your E-Book PDF Download(91 pages) of the entire Physics Key Points with well illustrative diagrams to quickly prep for JAMB & WAEC purchase here for N500 -https://dtwedustore.com/shop/physics-key-points-by-dtw-tutorials-e-book-91-pages

14.1     KEY CONCEPTS IN MOLECULAR THEORY 

• Brownian Motion: The random movement of particles suspended in a fluid, resulting from collisions with fast-moving molecules.
• Diffusion: The process by which molecules spread from areas of high concentration to areas of low concentration until evenly distributed.
• Surface Tension: The cohesive force at the surface of a liquid that causes it to behave like a stretched elastic membrane, due to the attraction between liquid molecules.
• Capillarity: The ability of a liquid to flow in narrow spaces without the assistance of external forces, caused by adhesive and cohesive forces.
• Adhesion: The attraction between different substances, such as water molecules and glass.
• Cohesion: The attraction between similar molecules, such as water molecules attracting each other.
• Angles of Contact: The angle formed at the interface between a liquid and a solid surface, which affects wetting and capillary action.

LAW OF DEFINITE PROPORTION: This law states that a chemical compound always contains its component elements in fixed ratio by mass, regardless of the sample size or source. For example, water (H2O) always consists of 2 hydrogen atoms and 1 oxygen atom.

          14.2     VAPOUR

Vapour is a substance in the gas phase at a temperature lower than its critical temperature.

TYPES OF VAPOURS

• Unsaturated Vapours: They are vapours that can still absorb more liquid without condensing.
• Saturated Vapours: They are vapours that are in equilibrium with their liquid phase, meaning they cannot absorb more liquid without condensing.

RELATIONSHIP BETWEEN SATURATED VAPOUR PRESSURE (S.V.P) AND BOILING: The boiling point of a liquid is the temperature at which its saturated vapour pressure equals the external atmospheric pressure. Higher S.V.P indicates a lower boiling point.

To get your E-Book PDF Download(91 pages) of the entire Physics Key Points with well illustrative diagrams to quickly prep for JAMB & WAEC purchase here for N500 -https://dtwedustore.com/shop/physics-key-points-by-dtw-tutorials-e-book-91-pages

          14.3     FORMATION OF DEW, MIST, FOG, CLOUDS, AND RAIN

• Dew: It forms when air cools and reaches its dew point, causing condensation.
• Mist and fog are formed by tiny water droplets suspended in the air due to high humidity.
• Clouds form when water vapour condenses into tiny droplets or ice crystals in the atmosphere.
• Rain: Rain occurs when these droplets combine and grow heavy enough to fall to the ground.
• Dew point: The dew point is the temperature at which air becomes saturated with moisture.
• Humidity: Humidity is the amount of water vapour in the air.
• Relative humidity: Relative humidity is the ratio of the current humidity to the maximum possible humidity at a given temperature, expressed as a percentage.