science

• Science came about to help people and to provide solutions to some of their problems
• Science


  A systematic body of knowledge based on facts and pieces of evidence through experimentation and observation
• Matter


  The smallest particle called a molecule, which is made up of a particle called an atom
• Arrangement of molecules


  • Closely packed in solids, loosely packed in liquids, far from each other in gases
• Atom


  The building block of matter that cannot be divided, from the Greek word 'atomos' meaning indivisible
• John Dalton in the early 1800s thought that atoms are the building blocks of matter
• Subatomic particles


  • Electron
  • Proton
  • Neutron
• Sir John Joseph Thomson discovered the electron in 1897, James Chadwick discovered the neutron in 1932, Ernest Rutherford discovered protons in 1917, Erwin Schrodinger developed an electron cloud model in 1926, Werner Heisenberg determined the region where electrons are found in 1907
• Pure substance


  Made up of one kind of material
• Types of pure substances

  • Compounds
  • Elements
• Elements


  • Can be metals, non-metals, and metalloids
• Metals


  • Mostly solid in form except for mercury, possess luster, good conductors, malleable and ductile
• Non-metals


  • Exist in solid, liquid and gas forms, act as insulators
• Examples of non-metals


  • Boron (used in fighter aircraft and glass)
  • Arsenic (used in cancer treatment but can be poisonous in large amounts)
  • Silicon (used in electronics and automotive parts)
• Compounds


  Combinations of two or more elements
• Examples of ionic compounds

  • Sodium chloride (table salt)
  • Sodium bicarbonate (baking soda)
• Mixture


  A combination of two or more substances in which each pure substance retains its individual chemical properties
• Types of mixtures


  • Homogeneous
  • Heterogeneous
• Homogeneous mixture


  Has uniform composition throughout, can be in solid or liquid form, only one phase is visible
• Heterogeneous mixture


  Does not have uniform composition, the individual substances are recognizable or remain distinct, the phases or substances are all visible
• Solution


  A homogeneous mixture which has a uniform composition, has two parts: solute (substance to be dissolved) and solvent (dissolving substance)
• Solubility


  A property of solutes that dissolves easily than others
• Concentrated solution


  More solute is added to the solvent
• Diluted solution


  More solvent is added to the same amount of solute
• Miscibility


  The ability of materials to mix well with water, liquids are miscible when they dissolve into each other to form a homogeneous mixture, liquids are immiscible when they do not dissolve into each other
• Suspension


  A heterogeneous mixture with particles suspended in a gas or liquid
• Examples of suspensions


  • Blood
  • Flour in water
• Colloid


  Has bigger and unevenly distributed particles in its dispersing medium
• Example of a colloid


  • Mayonnaise
• Colloids


  • Tyndall effect: scattering of light by the colloidal particles
  • Brownian movement: movements of particles suspended in a liquid or gas, caused by the impact of the fast-moving particles
• Components of colloids


  • Dispersed phase (substance being distributed)
  • Dispersion medium (substance in which the dispersed phase is distributed)
• Example of a colloid

  • Muddy water
• Distillation


  1. Process of separating mixed liquids

  2. Distillate is the liquid collected
• Rectification


  The process for separating mixed gases
• The skeletal system works as a support structure for the body, gives the body its shape, allows movement, makes blood cells, provides protection for organs and stores minerals
• Divisions of the skeletal system

  • Axial skeleton
  • Appendicular skeleton
• Axial skeleton


  • Protects delicate organs in the body, includes the skull, backbone, breastbone and ribs
• Appendicular skeleton


  • Provides support and aids the body in movement, includes the collarbones and shoulder blades
• An adult human being has 206 bones, a baby has 305 bones
• Muscle


  Consists of fibers or muscle cells that are held together, makes up 40% of total body weight