Chemistry- physical and chemical change, states of matter

• What is a physical change?

  A change that affects the form of a substance but not its chemical composition.
• What are the key characteristics of physical changes?

  They are often reversible and no new substances are formed.
• Can you give examples of physical changes?

  Melting, freezing, boiling, condensing, dissolving, cutting, tearing, bending, and mixing substances.
• What is a chemical change?

  A change that involves the formation of new substances with different properties.
• What are the key characteristics of chemical changes?

  They are often irreversible and new substances are formed.
• Can you provide examples of chemical changes?

  Burning, rusting, cooking, and mixing baking soda and vinegar.
• What are the differences between physical and chemical changes?

  • Physical Change:
  • No new substances formed
  • Often reversible
  • Examples: Melting ice, dissolving sugar
  • Chemical Change:
  • New substances formed
  • Often not reversible
  • Examples: Burning wood, rusting iron
• What should you observe to identify a chemical change?

  Look for signs like color change, temperature change, gas production, or a precipitate forming.
• How can you determine if a change is physical or chemical?

  If you can reverse the change, it's likely a physical change.
• What are the states of matter?

  Solid, liquid, gas, and plasma.
• What are the characteristics of solids?

  • Particles: Tightly packed in a regular pattern
  • Shape: Definite shape
  • Volume: Definite volume
  • Examples: Ice, rock, wood
• What are the characteristics of liquids?

  • Particles: Close together but not in a regular pattern
  • Shape: Takes the shape of its container
  • Volume: Definite volume
  • Examples: Water, milk, juice
• What are the characteristics of gases?

  • Particles: Spread out and far apart
  • Shape: Takes the shape of its container
  • Volume: Fills the container it's in
  • Examples: Air, oxygen, helium
• What are the characteristics of plasma?

  • Particles: Superheated gas that has lost some or all of its electrons
  • Shape: Takes the shape of its container
  • Volume: Fills the container it's in
  • Examples: Lightning, the sun, fluorescent lights
• How can matter change from one state to another?

  By adding or removing heat.
• What are the common changes of state?

  1. Melting: Solid to liquid (ice to water)
  2. Freezing: Liquid to solid (water to ice)
  3. Evaporation: Liquid to gas (water to steam)
  4. Condensation: Gas to liquid (steam to water)
  5. Sublimation: Solid to gas (dry ice to carbon dioxide gas)
  6. Deposition: Gas to solid (frost on a window)
• What are the building blocks of matter?

  Atoms
• What are atoms made up of?

  Protons, neutrons, and electrons
• What defines an element?

  Substances made up of only one type of atom
• What is the purpose of the periodic table?

  To organize all the known elements
• What are compounds made up of?

  Two or more different elements chemically combined
• How do mixtures differ from compounds?

  Mixtures are not chemically combined
• What is the characteristic of solids?

  They have a definite shape and volume
• What is the characteristic of liquids?

  They have a definite volume but no definite shape
• What is the characteristic of gases?

  They have no definite shape or volume
• What are reactants in a chemical reaction?


  The substances that react
• What are products in a chemical reaction?

  The substances that are formed
• What are the four types of chemical reactions?

  • Combination: Two or more substances combine to form a new substance.
  • Decomposition: A single substance breaks down into two or more simpler substances.
  • Displacement: One element replaces another in a compound.
  • Combustion: A substance reacts with oxygen to produce heat and light.
• What is a characteristic of acids?

  They taste sour and turn litmus paper red
• What is a characteristic of bases?

  They taste bitter and turn litmus paper blue
• What is neutralization in chemistry?

  A reaction between an acid and a base to form a salt and water