chemical reactions🧪🧪

• What do all chemical reactions involve?

  Formation of new substances
• How can chemical reactions be identified?

  By changes in appearance and energy
• What are some changes in appearance that indicate a chemical reaction?

  Colour change, gas evolved, precipitate formed
• What affects the speed of chemical reactions?

  Particle size, temperature, and concentration
• How do catalysts behave in reactions?

  They are not used up during the reaction
• What are catalysts?

  Substances that speed up reactions
• What are enzymes?

  Catalysts that affect living things
• Can you give examples of catalysts in everyday life?

  Transition metals in car exhaust systems
• How can I identify a chemical reaction?

  By a change in appearance of substance
• What indicates a detectable energy change in a chemical reaction?

  Heat release or absorption
• How many elements make up everything in the world?

  About 100 elements
• What does each element have?

  A name and a symbol
• What are compounds?

  Formed when elements react together
• What are mixtures?

  Two or more substances combined without reacting
• What is a solution?

  A solute dissolves in a solvent
• What do compounds with names ending in "ide" contain?

  Two elements indicated by the name
• What does the ending "ite" or "ate" indicate in a compound's name?

  Presence of an additional element oxygen
• How do particle size, concentration, and temperature affect reaction speed?

  • Smaller particle size increases surface area
  • Higher concentration increases the number of collisions
  • Higher temperature increases kinetic energy of particles
• Give examples of reactions affected by particle size, concentration, and temperature.

  1. Particle size: Powdered vs. whole reactants
  2. Concentration: Dilute vs. concentrated solutions
  3. Temperature: Cold vs. hot reactions
• What are the three key properties of catalysts?

  Speed up reactions, not used up, recoverable unchanged
• What is an everyday example of a catalyst?

  Transition metals in car exhaust systems