Nature of Matter and Chemical Compounds

Nature of Matter

• Matter occupies space and has mass, existing in solid, liquid, and gaseous states
• Elements are the simplest form of matter, composed of atoms
• Atoms consist of protons (positive charge), neutrons (neutral charge), and electrons (negative charge) arranged around a dense nucleus
• Electrons orbit in shells, each with a maximum number (2n²), where n is the shell number
• Ions are atoms that have gained or lost electrons to form a positive or negative charge
• Isotopes are atoms of the same element with different numbers of neutrons

Chemical Compounds

• 109 known elements form most matter through compounds
• Compounds comprise identical molecules with specific proportions of different atoms
• Chemical bonds form when atoms link, often by transferring electrons between molecules
• Mixtures are composed of two or more substances with their own characteristics

States of Matter

• Solids have a definite shape and volume, independent of container
• Liquids have a definite volume, taking the shape of their container
• Gases have no fixed shape or volume, filling their container

Topic 2: Statics

• Force: A force can accelerate bodies, start, stop, or change their motion
• Equilibrium: When the net force on an object is zero, it is in equilibrium at rest or uniform motion
• Levers: Simple machines that act as a force multiplier

Topic 2: Forces, Moments and Couples

• Force is a push or pull that can change a body's motion
• Moments and couples cause rotation
• Forces are represented as vectors

Elements of Theory of Stress, Strain and Elasticity

• Stress: Force per unit area causing deformation
• Strain: Deformation of material due to stress
• Elastic limit: Point where material returns to normal shape
• Hooke's Law: Strain is directly proportional to stress below elastic limit
• Tension: Resistance to pulling force
• Compression: Resistance to crushing force
• Shear: Adjacent layers slide past
• Torsion: Resistance to twisting

Aircraft Riveting

• Uses compressive forces

Pressure and Buoyancy

• Pressure in a fluid depends on height, gravity, and fluid density.
• Density is mass per unit volume
• Specific gravity compares densities to water, i.e. weight of material against water weight
• Buoyancy force equals weight of displaced fluid (Archimedes' principle)
  • An object floats if it displaces more fluid than its weight
  • Gasoline has a specific gravity of 0.72 meaning equal volume weighs 72% as much as water

Topic 2.2 Kinetics

• Displacement- difference between initial and final position
• Distance- total path taken
• Speed- rate of change of distance
• Velocity- speed with direction
• Acceleration - change in velocity

Topic 2.3 Dynamics

• Inertia is a property that resists changes in motion
• Newton's first law: An object stays at rest or in uniform motion unless acted upon by a net force
• Work: Force x distance (measured in Joules)
• Power: Rate of doing work (measured in Watts)

Periodic Motion

• Repeated motion, like oscillations or vibrations
• The energy is wave energy in periodic motion

Heat Transfer

• Conduction: Heat transfer through direct contact
• Convection: Heat transfer through fluid movement
• Heating water in a kettle, heating air in a house, atmospheric heat circulation are examples of convection.
• Calorie (cal): measures heat for raising the temperature of one gram of water by one degree Celsius.
• British thermal unit (Btu): measures heat for raising the temperature of one pound of water by one degree Fahrenheit.

### Thermal Energy and Latent Heat

• Latent heat: The amount of heat absorbed or released during a change of state without a change in temperature
• Latent heat of vaporization / evaporation: Amount of heat required to boil a liquid or turn it to gas
• Latent heat of fusion: Amount of heat required to melt a solid to liquid
• Sensible heat: The heat required that causes a change in temperature

Topic 2.4 Fluid Dynamics

• Liquids are generally incompressible
• Viscosity: Resistance of fluid flow (thick oil is more viscous than thin oil)
• Viscosity Index: How much viscosity changes with a temperature change (in lubricating oils, this helps the oil not change viscosity in a wide range of operating temps)
• Coanda Effect: Fluid tends to stick to curved surfaces (e.g., air around a curved wing)
• Boundary Layer: Region of reduced speed in fluid flow (crucial for airflow around objects)

Topic 3: Thermodynamics

• Energy conservation: Energy cannot be created nor destroyed, only transformed
• Thermal energy is energy related to heat, and it can be transformed into mechanical energy and viceversa
  • Thermal energy refers to heat (e.g., heat from combustion in an engine)
  • Kinetic energy is energy a body has because of its motion (e.g., expanding gases in a turbine)

Topic 4: Optics (Light)

• Visible light is electromagnetic radiation
• Speed of light is 3 x 10⁸ m/s in a vacuum
• Reflected light: Light bounces off a surface at the same angle it hit the surface
• Refracted light: Light bends when it passes through different materials.
• Refractive index (n) is a value that describes how much a substance slows light
• Dispersion: Spreading of light into different colours

This quiz explores the fundamental concepts of matter, including its states, atomic structure, and chemical compounds. You will learn about the roles of protons, neutrons, and electrons, as well as how atoms form bonds to create various substances. Test your understanding of the nature and behavior of matter along with its classification.