1.2- the periodic table

• How are elements arranged in the periodic table?

  By atomic (proton) number
• What is the significance of groups in the periodic table?

  Elements in groups have similar properties
• What do elements in the same periodic group have in common?

  Same amount of electrons in outer shell
• Who ordered the early periodic table by atomic weight?

  John Newlands
• What did John Newlands discover about element properties?

  Similar properties occurred every eighth element
• What limitation did Newlands' law of octaves have?

  It broke down after calcium
• How did Mendeleev arrange his periodic table?

  By atomic mass, not strictly
• What did Mendeleev do for undiscovered elements?

  Left gaps for undiscovered elements
• Why is it called a periodic table?

  Similar properties occur at regular intervals
• What confirmed Mendeleev's predictions about elements?

  Discovery of elements that filled gaps
• How did isotopes affect the periodic table's order?

  Explained inaccuracies in atomic weight order
• What particles were discovered in the early 20th century?

  Electrons, protons, and neutrons
• How are elements ordered in the modern periodic table?

  By atomic (proton) number
• Where are metals located in the periodic table?

  Left and bottom of the periodic table
• What defines metals in terms of ion formation?

  They form positive ions
• Where are non-metals found in the periodic table?

  Right and top of the periodic table
• What is a characteristic property of alkali metals?

  Single electron in outer shell
• How do alkali metals react with water?

  They create an alkaline solution and hydrogen
• What do alkali metals produce when reacting with oxygen?

  They create an oxide
• What is produced when alkali metals react with chlorine?

  They form a white precipitate
• How does reactivity change in Group 1 elements?

  Reactivity increases going down the group
• What are the reactions of lithium, sodium, and potassium with water, oxygen, and chlorine?

  • Lithium:
  • Water: Fizzes steadily, gradually disappears
  • Oxygen: Burns with red-tinged flame, produces white solid
  • Chlorine: Produces white powder settling on container sides
  • Sodium:
  • Water: Fizzes rapidly, melts into a ball
  • Oxygen: Burns with bright orange flame, produces white solid
  • Chlorine: Produces clouds of white powder settling on container sides
  • Potassium:
  • Water: Ignites with sparks, disappears quickly
  • Oxygen: Produces lilac flame, solid immediately
  • Chlorine: Reaction is more vigorous than sodium
• How many electrons do noble gases have in their outer shell?

  Eight electrons, except helium
• Why are noble gases unreactive?

  They have a stable arrangement of electrons
• How do boiling points of noble gases change?

  They increase with atomic mass down the group
• What do halogens have in common regarding their outer shell?

  They have seven electrons in their outer shell
• How do halogens exist in nature?

  As molecules made of pairs of atoms
• What type of compounds do halogens form with metals?

  Ionic compounds with halide ions
• What type of compounds do halogens form with nonmetals?

  Covalent compounds with shared electrons
• How do properties change as you go down Group 7?

  Molecular mass, melting, and boiling points increase
• How does reactivity change in Group 7 elements?

  Reactivity decreases going down the group
• Why does reactivity decrease in halogens down the group?

  More electron shells reduce attraction for electrons
• What happens when a more reactive halogen displaces a less reactive one?

  It can displace it in an aqueous solution
• What is the reaction of chlorine with potassium bromide?

  Chlorine displaces bromine in solution
• What is the equation for the reaction of chlorine with potassium bromide?

  Chlorine + Potassium Bromide → Potassium Chloride + Bromine