1.4 BONDING

• What are the three main types of chemical bonding?

  Ionic, covalent, and metallic
• What do 'dot and cross' diagrams represent in bonding?

  Outer electrons from different atoms
• What happens in ionic bonding?

  One atom donates electrons to another

  
• What is formed as a result of ionic bonding?

  A cation and an anion
• Why do ionic compounds have high melting points?

  Due to strong attractions between ions
• What is required when ions are formed in ionic bonding?

  Energy is required to form the ions
• What is covalent bonding?

  Atoms share electrons to form bonds

  
• How do electrons in a covalent bond spin?

  They have opposite spins
• What is co-ordinate or dative bonding?

  Both electrons come from the same atom
• What is the ammonium ion's formula?

  NH4+

  
• What determines bond length in covalent bonds?

  Attraction and repulsion between electrons and protons

  
• What happens if atoms get too close in a covalent bond?

  Inner electrons and nuclei repel each other

  
• How are cations and anions arranged in ionic bonds?

  To maximize attraction and minimize repulsion

  
• What are intermolecular forces?

  Forces between molecules
• What do intermolecular forces determine?

  Physical properties of compounds
• What are intramolecular forces?

  Forces within molecules
• Why do covalent compounds have low melting and boiling points?

  Intermolecular forces are very weak

  
• What type of intermolecular force is the weakest?

  Induced dipole-dipole interactions
• How do induced dipole-dipole interactions occur?

  Due to temporary dipoles in molecules
• What are dipole-dipole interactions?

  Interactions between polar molecules
• What is hydrogen bonding?

  The strongest intermolecular force
• Between which atoms does hydrogen bonding occur?

  Hydrogen, fluorine, oxygen, and nitrogen
• How does hydrogen bonding affect boiling points?

  It increases boiling temperatures significantly

  
• What does VSEPR theory help determine?

  The shapes of simple molecules
• What is the first step in using VSEPR theory?

  Count lone pairs and bonding pairs
• What shapes do molecules form based on electron pairs?

  • Linear: 2 pairs, 180°
  • Trigonal planar: 3 pairs, 120°
  • Tetrahedral: 4 pairs, 109.5°
  • Trigonal bipyramidal: 5 pairs, 90°/120°
  • Octahedral: 6 pairs, 90°

  
• How do lone pairs affect molecular shapes?

  • Lone pairs repel more than bonding pairs
  • They distort bond angles
  • Example: Water has a v-shape due to lone pairs
• What are the bond angles for specific molecular shapes?

  • Linear: 180°
  • Trigonal planar: 120°
  • Tetrahedral: 109.5°
  • Trigonal bipyramidal: 90°/120°
  • Octahedral: 90°

  
• What is the effect of hydrogen bonding on boiling points in groups 5, 6, and 7?

  • Hydrogen bonding raises boiling points significantly
  • This is contrary to trends in other groups
  • Example: Water has a higher boiling point than expected

  
• What is the sequence of repulsion for electron pairs?

  • Lone pair – lone pair > lone pair – bonding pair > bonding pair – bonding pair
• What are the examples of molecular shapes and their bond angles?

  • BeCl2: Linear, 180°
  • BF3: Trigonal planar, 120°
  • CH4: Tetrahedral, 109.5°
  • PCl5: Trigonal bipyramidal, 90°/120°
  • SF6: Octahedral, 90°

  
• What is the significance of the Pauling electronegativity scale?

  • It measures the electronegativity of elements
  • Used to determine bond polarity
  • Not required to memorize for exams

  
• What is the relationship between electronegativity and bond character?

  • Larger electronegativity difference leads to more polar bonds
  • Polar covalent bonds have some ionic character
  • Example: HCl has 19% ionic character
• What are the characteristics of van der Waals forces?

  • Very weak intermolecular forces
  • Include induced dipole-dipole and dipole-dipole interactions
  • Important in determining physical properties

  
• What is the role of intermolecular forces in covalent compounds?

  • Determine physical properties like melting and boiling points
  • Weaker than intramolecular forces
  • Require less energy to break