Chem unit 1

• What term describes noble gases that occur as single atoms?

  Monatomic
• Why do noble gases have very weak attraction between their atoms?


  They have a full outer shell of electrons.
• What is the name of the attraction between noble gas atoms?

  London dispersion force (LDF)
• How do temporary dipoles arise in atoms?

  Electrons become unevenly distributed, creating a temporary dipole.
• What effect do temporary dipoles have on neighboring atoms?

  They induce temporary dipoles in neighboring atoms.
• How do London dispersion forces compare to other types of bonding?


  They are much weaker than all other types of bonding.
• What happens to the strength of London dispersion forces as the size of the atom increases?


  The strength of London dispersion forces increases.
• What trend is observed in the boiling points of noble gases as you go down the group?


  The boiling points increase.
• Why do boiling points of noble gases increase down the group?


  Atoms have more electrons, leading to stronger LDFs.
• What are the characteristics of covalent molecules?


  • Exist as discrete molecules
  • Held together by covalent bonds
  • Have a definite formula
• What is the formula for hydrogen as a covalent molecule?


  H₂
• What is the state of phosphorus (P₄) at room temperature?


  Solid
• Why do covalent molecular substances have low melting and boiling points?


  They are held together by weak London dispersion forces.
• What must be supplied to separate atoms in a covalent molecule?


  Energy
• What happens to the energy needed to separate covalent molecules compared to ionic compounds?


  Only a little energy is needed for covalent molecules.
• What are the three crystalline forms of carbon?


  • Diamond
  • Graphite
  • Fullerenes
• What are fullerenes made of?


  Carbon atoms in a cage-like structure.
• What type of bonding occurs in ionic compounds?


  Attraction between positive and negative ions.
• What is covalent bonding?

  Atoms share electrons.
• What are the two types of covalent compounds?


  • Covalent molecular compounds: discrete particles with a definite formula.
  • Covalent network compounds: giant lattice of covalently bonded atoms.
• What is the arrangement of particles in ionic compounds?


  They form a lattice structure.
• What happens to potassium nitrate when placed in boiling water?


  It does not melt.
• What happens to paraffin when placed in boiling water?


  It melts.
• What is the melting point of ionic compounds generally?

  Higher than 1000 °C
• What is the relationship between the type of bonding and the properties of a compound?


  The type of bonding affects the melting and boiling points.
• What is the reaction represented by the equation Mg(s) + 2FeCl₃(aq) → MgCl₂(aq) + 2FeCl₂(aq)?

  It is a redox reaction.
• What does the equation 2Ag⁺ + 2e⁻ → 2Ag represent?

  Reduction of silver ions to silver metal.
• What does the equation 2I⁻ → I₂ + 2e⁻ represent?

  Oxidation of iodide ions to iodine.
• What does the equation 2Fe³⁺ + 2e⁻ → 2Fe²⁺ represent?

  Reduction of iron(III) ions to iron(II) ions.
• What does the equation Li(s) → Li⁺(aq) + e⁻ represent?

  Oxidation of lithium metal to lithium ions.