1.2

• What was the initial basis for ordering the periodic tables?

  Atomic weight
• What significant discovery was made after Mendeleev's time?

  Isotopes
• What did Mendeleev do regarding undiscovered elements?

  Left gaps in the periodic table
• Why didn't Mendeleev strictly follow atomic mass in his periodic table?

  Because of different atomic masses
• How is the position of an element in the periodic table used?

  To predict its reactivity
• What does each period in the periodic table represent?

  A new shell of electrons
• What does the group number indicate in the periodic table?

  The number of valence electrons
• What are the characteristics of Group 1 elements?

  • One electron in outer shell
  • Very reactive
  • Form ionic compounds
  • React with water, chlorine, and oxygen
• How does reactivity change in Group 1 as you move down the group?

  Reactivity increases down the group
• What happens to melting and boiling points as you move down Group 1?

  They increase
• What is the trend in reactivity for halogens as you move down the group?

  Reactivity decreases down the group
• What is a characteristic of noble gases?

  They are unreactive
• What happens to the boiling point of noble gases as you move down the group?

  It increases
• What is the electron configuration of metals in relation to ion formation?

  Metals form positive ions
• How do non-metals behave in terms of ion formation?

  Non-metals do not form positive ions
• What are the general properties of metals and non-metals in the periodic table?

  Metals:

  • Strong, malleable, good conductors
  • High melting points

  
  

  Non-metals:

  • Brittle, dull looking, do not conduct electricity
• Where are non-metals generally located in the periodic table?

  Towards the top right
• Where are metals generally located in the periodic table?

  Towards the bottom left
• What was a limitation of early periodic tables?

  They were incomplete
• What was a common issue with the placement of elements in early periodic tables?

  Some elements were placed in incorrect groups
• What was Mendeleev's approach to grouping elements?

  He ensured elements with similar properties lined up in groups
• What is a characteristic of elements in the same group of the periodic table?

  They have similar chemical properties