Periodic test

• What should you be able to describe by the end of the video?

  Early attempts to arrange elements
• Why is it called the periodic table?

  Elements occur at regular intervals
• What are the groups in the periodic table called?

  Columns
• Which groups are mentioned in the periodic table?

  Group 1, Group 2, Group 0
• What do elements in the same group have in common?

  Similar chemical properties
• What is the significance of outer energy level electrons?

  They determine chemical reactivity
• Who was Johann Dobereiner?

  • Scientist who noticed triads of elements
  • Elements with similar properties grouped in threes
• What did Dobereiner's triads consist of?

  Elements with similar chemical properties
• What did John Newlands arrange elements by?

  Increasing atomic weight
• What is Newlands' law of octaves?

  Every eighth element reacts similarly
• What was a problem with Newlands' system?

  Elements grouped with different properties
• Who developed the first modern periodic table?

  • Dmitri Mendeleev
  • Arranged elements by atomic weight
• What did Mendeleev do if elements did not fit the pattern?

  He switched their order
• What did Mendeleev leave in his table for undiscovered elements?

  Gaps
• How did Mendeleev predict properties of undiscovered elements?

  Based on patterns in similar groups
• What is the main difference between Mendeleev's and the modern periodic table?

  Modern table uses atomic number
• What had not been discovered when Mendeleev published his table?

  Protons
• What issue arises from ordering elements by atomic weight?

  Elements can appear in the wrong order
• What group was added to the modern periodic table?

  Group 0, noble gases
• What should you be able to explain after watching the video?

  • Early attempts to arrange elements
  • Mendeleev's successful predictions
  • Arrangement of elements in the modern periodic table
• Who was Dmitri Mendeleev?

  A Russian chemist and inventor
• What did Mendeleev devise in the mid-nineteenth century?

  The periodic table of elements
• What does the periodic table organize?

  All known elements
• What did Mendeleev's periodic table predict?

  New elements not yet discovered
• How are elements arranged in the periodic table?

  By increasing atomic number
• What does the atomic number represent?

  The number of protons in an atom
• What is found within each box of the periodic table?

  The nucleus symbol for that element
• What is the elemental symbol for sodium?

  Na
• What does the atomic number indicate?

  How many protons the atoms have
• What does the mass number tell us?

  Total number of protons and neutrons
• What pattern did Mendeleev observe in the elements?

  Repeating chemical properties at intervals
• What are the horizontal rows in the periodic table called?

  Periods
• What do elements in the same vertical column share?

  Similar chemical properties
• What is the group number for the far-right group?

  Group 0
• Why do elements in the same group have similar properties?

  Same number of electrons in outer shell
• How many electrons do elements in Group 2 have in their outer shell?

  Two electrons
• What are the elements in Group 1 called?

  Alkali metals
• What do all Group 1 elements have in common?

  One electron in the outer shell
• How do Group 1 elements react with water?

  Violently
• What trend is observed in Group 1 elements as you move down the group?

  They become more reactive