The periodic table

• How many elements are there in the periodic table?

  92 naturally occurring elements
• Why are elements arranged in the periodic table?

  They are arranged by atomic mass
• What fraction of the elements are metals?

  About three quarters
• Why are elements grouped in the periodic table?

  Elements in a group have similar properties
• What does the big number next to each element represent?

  Relative atomic mass
• What does the small number next to each element represent?

  Atomic number
• What is the atomic number of hydrogen?

  1
• What is the atomic number of helium?

  2
• What are the main groups in the periodic table?

  Groups one, two, seven, and zero
• What are the names of the blocks in the periodic table?

  S block, P block, D block, F block
• What is ionization energy?

  Energy needed to remove an electron
• What is the first ionization energy?

  Energy to remove one electron from an atom
• Which atoms have small ionization energy?

  Atoms with one or two outer electrons
• Which atoms have large ionization energy?

  Atoms with nearly full outer shells
• How does ionization energy change across a period?

  It increases from left to right
• How does ionization energy change down a group?

  It decreases as you go down
• What is electron affinity?

  Energy released when an atom gains an electron
• Which type of atoms typically have high electron affinity?

  Non-metals
• Which group has the highest electron affinity?

  Group seven (halogens)
• What happens when a neutral atom gains an electron?

  Energy is released
• Why do period three elements have smaller ionization energies than period two?

  They have another shell, further from nucleus
• What are the trends in ionization energy across periods and down groups?

  • Across a period: Ionization energy increases
  • Down a group: Ionization energy decreases
• What are the key properties of the periodic table?

  • Arranged by atomic mass
  • Groups have similar properties
  • Metals make up about three quarters
  • Blocks correspond to subshells
• What mnemonic can help remember the first 20 elements?

  • Harry Henry Likes Being Bored, CUpfuls Not Overflowing
• What is the significance of the transition metals?

  • They are located in the middle of the periodic table
  • Not the focus for basic understanding
• What is the relationship between ionization energy and atomic structure?

  • More protons increase attraction, raising ionization energy
  • Additional shells decrease attraction, lowering ionization energy
• What is the relationship between electron affinity and non-metals?

  • Non-metals tend to have high electron affinity
  • They release energy when gaining electrons