UNIT 1 CHEM

• What can atoms combine to form?

  A huge variety of substances
• What are substances made of only one type of atom called?

  Elements
• What is the smallest part of an element that can exist?

  An atom
• What are some properties of metals like silver and gold?

  They are shiny and solid
• What are some examples of non-metals that are gases at room temperature?

  Oxygen, nitrogen, argon, chlorine
• Why are chemical symbols important in science?

  They allow global communication among scientists
• What is the periodic table used for?

  • Displays symbols for elements
  • Facilitates global scientific communication
  • Organizes elements by atomic number
• What is the purpose of symbols in the periodic table?

  To represent elements universally
• How do elements differ from each other?

  They can have very different properties
• What do the symbols in the periodic table represent?

  Atoms
• What does the symbol O represent in the periodic table?

  An atom of oxygen
• What does the symbol Na represent in the periodic table?

  An atom of sodium
• How are elements arranged in the periodic table?

  In columns called groups
• What do elements in the same group have in common?

  Similar chemical properties
• What are metalloids?

  Elements with both metallic and non-metallic properties
• Give two examples of metalloids.

  Silicon and germanium
• What are compounds?

  Substances made of different types of atoms bonded together
• What is the chemical formula for water?

  H₂O
• What holds atoms together in compounds?

  Chemical bonds
• What is the structure of an atom?

  A nucleus with electrons orbiting around it
• What is the purpose of chemical equations?

  To show reactants and products in a reaction
• What do reactants represent in a chemical equation?

  The substances you start with
• What do products represent in a chemical equation?

  The new substances made
• What happens to atoms during a chemical reaction?

  They get rearranged
• What does the Law of conservation of mass state?

  The total mass of products equals reactants
• Why might mass appear to be lost in reactions with gases?

  Gases escape into the air
• What happens to copper's mass when heated in air?

  It increases due to oxygen reaction
• How can you check if a chemical equation is balanced?

  By counting the number of each type of atom
• What are state symbols used for in chemical equations?

  To indicate the physical state of substances
• Why must all symbol equations be balanced?

  To conserve mass in reactions
• What is the first step in balancing the equation H₂ + O₂ → H₂O?

  Count the atoms on either side
• What is the balanced equation for hydrogen reacting with oxygen?

  2H₂ + O₂ → 2H₂O
• What is a mixture?

  Two or more substances combined
• How do mixtures differ from compounds?

  Mixtures have no fixed composition
• What is the role of filtration in separating mixtures?

  To separate insoluble from soluble substances
• What is crystallisation used for?

  To obtain pure solids from solutions
• What is distillation used for?

  To separate liquids based on boiling points
• What is chromatography used for?

  To separate components in a mixture
• What is the purpose of a fractionating column in distillation?

  To separate liquids with similar boiling points
• What happens to the temperature in a fractionating column?

  It decreases as vapours rise