6.2.1 Physical and Chemical Properties

• What type of elements are halogens?

  Non-metal elements
• Why do halogens need one more electron?

  To become stable
• How many valence electrons do halogens have?

  7 valence electrons
• What are the physical states and colors of halogens at room temperature?

  • Fluorine (F₂): Gas, Pale yellow
  • Chlorine (Cl₂): Gas, Green-yellow
  • Bromine (Br₂): Liquid, Red-brown
  • Iodine (I₂): Solid, Dark grey/purple
• In what types of products are halogens used?

  Some are used in everyday products
• What role do halogens play in chemical reactions?

  They are crucial in chemical reactions
• How do melting and boiling points of halogens change down the group?

  They increase due to stronger intermolecular forces
• What is the trend for reactivity in Group 1 of the alkali metals?

  increase in reactivity
• In what form do halogens typically exist?

  Diatomic molecules
• What happens to the atomic radius as we go down Group 1?

  It increases
• Why does the ease of losing the outer electron increase down Group 1 of the alkali metals?

  a tendency for the melting points and boiling points to decrease
• What happens to the melting point as we go down Group 1?

  It generally decreases
• Why does the atomic radius increase down Group 1?

  More electron shells are added
• What are the key trends observed in Group 1 of the alkali metals?

  • Increase in reactivity
  • Increase in atomic radius
  • Increase in electron shells shielding the outer electron
  • Increase in ease of losing outer electron to form a positive ion
  • Decrease in melting and boiling points
  • Increase in density (first three float on water)
• What happens to the boiling point as we go down Group 1?

  It generally decreases
• Which alkali metals can float on water?

  Li, Na, K
• How many more electrons do halogens need for stability?

  One more electron
• What causes the trends in physical properties down Group 1?

  • Increased electron shielding
  • Increased nuclear attraction forces
• What is the trend for atomic radius in Group 1 of the alkali metals?

  increase in atomic radius
• Why does the atomic radius increase down Group 1 of the alkali metals?

  increase in electron shells shielding the outer electron
• What is the molecular form of halogens?

  Diatomic molecules
• What is the relationship between atomic radius and electron affinity?

  As atomic radius increases, electron affinity decreases
• What happens in a displacement reaction involving halogens?

  A more reactive halogen replaces a less reactive one
• What is formed when halogens gain an electron?

  Negative halide ions
• What is the relationship between atomic radius and ionization energy?

  As atomic radius increases, ionization energy decreases
• What is electron affinity?

  Energy change when an electron is gained
• What are the trends in atomic radius, ionization energy, and electron affinity across the periodic table?

  • Atomic radius increases from top to bottom and left to right
  • Ionization energy decreases from top to bottom and increases from left to right
  • Electron affinity decreases from top to bottom and increases from left to right
• How do electron affinity and ionization energy change down Group 7?

  Both values decrease
• How does atomic size affect the attraction of outermost electrons?

  It makes it harder to attract new electrons
• What is the trend for the density of the alkali metals in Group 1?

  a tendency for the density to increase (first three float on water)
• Why do melting and boiling points increase in halogens as you go down the group?

  Due to stronger intermolecular forces between heavier molecules
• What happens when chlorine is added to sodium bromide?

  It yields sodium chloride and bromine
• What is the effect of increasing atomic size on the outermost electrons?

  They are further from the nucleus
• What is produced when sodium reacts with chlorine?

  Sodium chloride (NaCl)
• Why does the force of attraction to outer electrons weaken down Group 7?

  Due to increased atomic size
• What do halogens form when they react with metals?

  Salts
• Why does chemical reactivity decrease down Group 7?

  Because atomic size increases
• What happens to chemical reactivity as we move down Group 7?

  It decreases
• What is the product of the reaction between chlorine and sodium bromide?

  Sodium chloride and bromine
• What is the halide ion formed from chlorine?

  Chloride (Cl⁻)