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
• How did Mendeleev's periodic table predict new elements?

  It displayed patterns that suggested the existence of undiscovered elements
• How are 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
• Why did Mendeleev form a new row in the periodic table?

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

  Periods
• What do the elements in each vertical column of the periodic table have in common?

  They have similar chemical properties
• How are the groups in the periodic table numbered?

  Starting with one on the far left and going to seven
• What is unique about Group 0 in the periodic table?

  It is called Group 0 rather than Group 8
• Why do elements in the same group have similar chemical properties?

  They have the same number of electrons in their outermost shell
• How many electrons do elements in Group 2 have in their outermost shell?

  Two electrons
• What are alkali metals?


  Elements in Group 1 that all have one electron in their outer shell
• What happens to the reactivity of Group 1 elements as you move down the group?

  They become more reactive
• What are halogens?

  Elements in Group 7 that all have seven electrons in their outer shell
• How does the reactivity of Group 7 elements change as you go down the group?

  They become less reactive
• What are noble gases?

  Elements in Group 0 that have full outer shells
• How many electrons does argon have in its outer shell?

  Eight electrons
• How many electrons does helium have in its outer shell?

  Two electrons
• Why are noble gases considered unreactive?

  They do not need to gain or lose any electrons
• What does the zigzag line in the periodic table represent?


  It separates metals from nonmetals
• What are transition metals?


  A special block of elements in the middle of the 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 will be the smaller of the two numbers
• 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