1.9 Development of the Periodic Table

• Who was Dmitri Mendeleev?

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

  He devised the periodic table
• What does the periodic table organize?

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

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

  In order of increasing atomic number
• What does the atomic number represent?

  The number of protons in the atoms of that element
• What three components are found within each box of the periodic table?

  Elemental symbol, atomic number, and mass number
• What is the elemental symbol for sodium?

  Na
• What does the mass number indicate?

  The total number of protons and neutrons in an atom
• What pattern did Mendeleev observe while organizing the periodic table?

  The elements displayed a pattern of chemical properties that repeated at regular intervals
• What do we call the new row formed in the periodic table when a pattern repeats?

  Periods
• What do we call the vertical columns in the periodic table?

  Groups
• How many groups are there in the periodic table?

  Seven
• Why is the far-right group called group 0?

  Because it contains noble gases with full outer shells
• What determines how an element reacts?

  The number of electrons in its outermost shell
• How many electrons do elements in group two have in their outermost shell?

  Two electrons
• What do all group one elements have in common regarding their outer shell?

  They all have one electron in their outer shell
• What is a characteristic reaction of group one elements?

  They react violently with water
• How does reactivity change among group one elements?

  It becomes more reactive as you go down the group
• What do we call group seven elements?

  Halogens
• How many electrons do group seven elements have in their outer shell?

  Seven electrons
• How does reactivity change among group seven elements?

  It becomes less reactive as you go down the group
• What are noble gases characterized by?

  Full outer shells of electrons
• What is the outer shell electron configuration of argon?

  Eight out of eight electrons
• What is the outer shell electron configuration of helium?

  Two out of two electrons
• What separates metals from nonmetals in the periodic table?

  A zigzag line running from aluminum to polonium
• What is the special block of elements found between metals and nonmetals called?

  Transition metals
• What should you remember about different types of periodic tables you might find online?

  They present the same information in slightly different ways
• How can you identify the atomic number in a periodic table?

  It is the smaller of the two numbers presented
• What will the periodic table provided in an exam be similar to?

  It will be similar to the one used throughout the video
• What should you do if you enjoyed the video?

  Give it a like and subscribe