periodic table classification

• What are the two main classifications of the periodic table?

  Periods and groups
• What does the position of an element in the periodic table indicate?

  It indicates its electron configuration, properties, and reactivity
• What does a period in the periodic table represent?


  The number of electron shells/energy levels
• How many electron shells do Period 3 elements have?


  Three electron shells
• How many valence electrons do alkali metals have?


  One valence electron
• Why are halogens very reactive?


  They have seven valence electrons
• What characterizes noble gases in the periodic table?


  They are stable, inert gases with full valence shells
• What is a unique property of transition elements?


  They have partially filled d-orbitals
• What are the four blocks of the periodic table?

  • s-block: Groups 1 and 2
  • p-block: Groups 13 to 18
  • d-block: Transition metals
  • f-block: Lanthanides and actinides
• Where are metals located in the periodic table?


  On the left side
• How do metals typically behave in terms of electrons?


  They lose electrons to form cations
• What is the characteristic behavior of non-metals in the periodic table?


  They gain electrons to form anions
• What do metalloids exhibit?

  Properties of both metals and non-metals
• What does the period number indicate about an atom?


  The highest energy level occupied by electrons
• What is the electron configuration of potassium (K)?


  1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
• How does atomic radius change across a period and down a group?


  Decreases across a period and increases down a group
• Why do cations have a smaller radius than their parent atoms?


  They lose an outer electron shell
• What happens to the ionic radius of anions compared to their parent atoms?


  Anions are larger than their parent atoms
• What is ionization energy?


  The energy required to remove an electron from a neutral atom
• How does ionization energy change across a period?


  It increases across a period
• How does ionization energy change down a group?


  It decreases down a group
• What is electron affinity?


  The energy released when an atom gains an electron
• How does electron affinity change across a period?


  It becomes more negative across a period
• How does electron affinity change down a group?


  It decreases down a group
• What is electronegativity?


  The ability of an atom to attract bonding electrons
• How does electronegativity change across a period?


  It increases across a period
• How does electronegativity change down a group?


  It decreases down a group
• What does oxidation state represent?


  The number of electrons lost, gained, or shared in forming bonds
• What is the oxidation state of oxygen in most compounds?


  • 2, except in peroxides where it is -1
• What is the oxidation state of hydrogen with metals?


  • 1
• What is the sum of oxidation states in a neutral compound?


  Zero
• What are oxyanions?


  Polyatomic ions that contain oxygen
• What is the oxidation state of nitrogen in nitrate (NO₃⁻)?


  +5
• What is the oxidation state of sulfur in sulfate (SO₄²⁻)?


  +6
• What is the oxidation state of carbon in carbonate (CO₃²⁻)?


  +4
• Why do some ions have Roman numerals in their names?


  To show the oxidation state of the central atom
• How are ionic bonds formed?


  When a metal transfers electrons to a non-metal
• What happens to metals during ionic bond formation?


  They lose electrons to form cations
• What happens to non-metals during ionic bond formation?


  They gain electrons to form anions
• What is the result of the attraction between oppositely charged ions?


  It forms an ionic bond