C2

• What do elements in the same period have in common?

  Same number of energy levels
• How are elements arranged in the modern periodic table?

  By atomic number and similar properties
• Why is it called a periodic table?

  Because similar properties occur at regular intervals
• What do elements in the same group have in common?

  Same number of outer electrons
• Why do elements in the same group have similar chemical properties?

  Due to having the same outer shell electrons
• What happens to the number of shells as you go down a group?

  The number of shells increases
• What does the atomic number represent?

  Number of protons or electrons
• What did Mendeleev do to improve the periodic table?

  Left gaps for undiscovered elements
• Why were early periodic tables incomplete?

  They were based on atomic weights only
• How did knowledge of isotopes affect the periodic table?

  It explained inaccuracies in atomic weight order
• What defines metals in the periodic table?

  They form positive ions
• Where are metals located in the periodic table?

  Left and bottom of the table
• What are noble gases known for?

  Being unreactive with stable electron arrangements
• How many electrons do noble gases have in their outer shell?

  Eight, except helium which has two
• What trend is observed in the boiling points of noble gases?

  They increase with relative atomic mass
• What do all Group 1 elements have in common?

  One electron in their highest energy level
• Why are Group 1 metals stored under oil?

  To prevent reactions with oxygen or water
• What do Group 1 metals form when they react with non-metals?

  Ionic compounds with a +1 charge
• What is the reaction of sodium with chlorine?

  $2Na +$$Cl_2 \rightarrow 2NaCl$
• What do Group 1 metals produce when reacting with water?

  Hydrogen and alkaline hydroxides
• What is the reaction of sodium with water?

  $2Na +$$2H_2O \rightarrow 2NaOH +$$H_2$
• How does reactivity change in Group 1 as you go down the group?

  Reactivity increases as you go down
• What happens to the size of atoms in Group 7 as you go down?

  Atoms get larger
• What trend is observed in the melting and boiling points of Group 7 elements?

  They increase down the group
• How many electrons do Group 7 elements have in their highest energy level?

  Seven electrons
• What type of compounds do Group 7 elements form with metals?

  Ionic salts with a -1 charge
• What type of compounds do Group 7 elements form with non-metals?

  Molecular (simple covalent) compounds
• What occurs in a displacement reaction involving halogens?

  A more reactive halogen displaces a less reactive one
• Where are transition metals located in the periodic table?

  Between Groups 2 and 3
• How do transition metals compare to Group 1 metals?

  They are less reactive and harder
• What are some properties of transition metals?

  Higher melting points and different charge ions
• What is a common use of transition metals?

  As catalysts in chemical reactions
• What are the key features of the modern periodic table?

  • Arranged by atomic number
  • Groups have similar properties
  • Periods have the same number of energy levels
  • Elements in the same group have the same outer electrons
• What are the characteristics of Group 1 elements?

  • One electron in highest energy level
  • Low density metals
  • React vigorously with water
  • Form +1 ionic compounds
• What are the characteristics of Group 7 elements?

  • Seven electrons in highest energy level
  • Coloured vapours
  • Form ionic salts with metals
  • Form molecular compounds with non-metals
• What are the properties of transition metals?

  • Higher melting points than Group 1
  • Stronger and harder
  • Less reactive
  • Form coloured compounds and different charge ions