Chemical Reactions

• What are ionic compounds?


  Formed by transfer of electrons between metals and non-metals
• What are cations?


  Positively charged ions from losing electrons
• What are anions?


  Negatively charged ions from gaining electrons
• What are acids?


  Substances donating protons in solution, pH < 7
• What are bases?


  Substances accepting protons or producing OH⁻, pH > 7
• What are indicators?


  Substances changing colour based on pH levels
• What is an oxidation reaction?


  Combination of oxygen with substances, energy transfer
• What are all substances made of?

  Atoms
• What are molecules made of?


  Non-metal atoms chemically bonded together
• What distinguishes a molecule of an element from a molecule of a compound?


  A molecule of an element has the same type of atoms, while a compound has different types of atoms
• What is a compound made from?


  Two or more different elements that are chemically bonded together
• How can elements in a compound be separated?


  Only by chemical reactions
• What is an ion?


  An atom or molecule with a net electric charge
• What is a polyatomic ion?


  An ion consisting of many atoms
• What is the maximum number of electrons in the 1st energy level?


  2
• What is the maximum number of electrons in the 2nd energy level?


  8
• What is the maximum number of electrons in the 3rd energy level?


  8
• What is the maximum number of electrons in the 4th energy level for the first 20 elements?


  2
• What is a proton?


  A subatomic particle with a positive charge found in the nucleus
• What is a neutron?


  A subatomic particle with no charge found in the nucleus
• What is an electron?


  A subatomic particle with a negative charge that orbits the nucleus
• Where is most of an atom's mass concentrated?

  In the nucleus
• Why is mass always conserved in a reaction?


  Because no atoms are lost or made; they are just rearranged
• What must be true about the mass of reactants and products in a chemical reaction?


  The mass of the reactants will be the same as the mass of the products
• What is an alkali?


  A base that dissolves in water
• What is an alkaline solution?


  A solution that contains a base
• What does litmus paper do?


  Turns red when exposed to an acid and blue when exposed to a base
• What does the pH scale represent?


  The acidity or basicity of a solution
• What does a pH less than 7 indicate?


  It indicates an acid
• What does a pH greater than 7 indicate?


  It indicates a base
• What does a pH of 7 indicate?


  It indicates a neutral solution
• How are strong acids and weak acids categorized on the pH scale?


  Strong acids are 1, 2, 3; weak acids are 4, 5, 6
• How are weak alkalis and strong alkalis categorized on the pH scale?


  Weak alkalis are 8, 9, 10; strong alkalis are 11, 12, 13, 14
• What are the general reactions involving acids?

  • Acid + metal → salt + hydrogen gas
  • Acid + base → salt + water
  • Acid + carbonate → salt + water + carbon dioxide gas