1.4 bonding

• What is a covalent bond?

  A covalent bond has a pair of electrons of opposed spin shared between two atoms.
• What is a co-ordinate bond?

  A co-ordinate bond is a covalent bond where both electrons come from one of the atoms.
• How is an ionic bond formed?

  An ionic bond is formed by the attractions between positive ions (cations) and negative ions (anions).
• What are the three main types of chemical bonding?

  The three main types of chemical bonding are ionic, covalent, and metallic.
• What is the significance of inert gases in terms of atomic existence on Earth?

  Only inert gases exist as single atoms on Earth; all other elements are bonded together.
• How can bonds be represented visually?

  Bonds may be represented by 'dot and cross' diagrams showing outer electrons as dots or crosses.
• What is the role of electron spins in covalent bonding?

  In covalent bonding, each atom gives one electron to the bond pair, and the spins must be opposed.
• What occurs during ionic bonding?

  In ionic bonding, one atom gives one or more electrons to another, resulting in cations and anions that attract each other.
• Why is energy needed in ionic bonding?

  Energy is needed to form the ions from atoms, but this is repaid by the strong attraction between cations and anions.
• What are the attractive and repulsive forces in bonding?

  All bonding results from electrical attractions and repulsions between protons and electrons.
• How do covalent bonds maintain their length?

  Covalent bonds have a certain length due to the balance of attractions and repulsions when atoms are close together.
• How are cations and anions arranged in ionic bonding?

  Cations and anions are arranged so that each cation is surrounded by several anions to maximize attraction.
• What is electronegativity?

  Electronegativity is a measure of an atom's ability to attract the electron pair in a covalent bond.
• What is the range of electronegativity values?

  Electronegativity values range from 0.7 in Cs to 4.0 in F.
• What happens to bonds between non-identical atoms?

  Almost all bonds between non-identical atoms will be polar to some extent.
• How is bond polarity determined?

  Bond polarity is governed by the difference in electronegativity between the two atoms forming the bond.
• What is a dipole?

  A dipole is the separation of charge within a molecule.
• What are van der Waals forces?

  Van der Waals forces are weak intermolecular forces made up of dipole-dipole and induced dipole-induced dipole attractions.
• What distinguishes intermolecular bonding from intramolecular bonding?

  Intermolecular bonding is weak and governs physical properties, while intramolecular bonding is strong and governs chemical reactivity.
• How do intermolecular forces affect boiling points?

  Stronger intermolecular forces generally lead to higher boiling points.
• What is hydrogen bonding?

  Hydrogen bonding is a strong bond between molecules containing hydrogen attached to very electronegative atoms with lone pairs.
• Why is hydrogen bonding stronger than van der Waals forces?

  Hydrogen bonding is stronger because the small hydrogen atom is sandwiched between two electronegative elements.
• How does hydrogen bonding affect the structure of water?

  Hydrogen bonding allows the formation of a tetrahedral structure in water due to the arrangement of hydrogen and oxygen atoms.
• How do intermolecular forces affect melting and boiling temperatures?

  Melting and boiling temperatures increase with the strength of intermolecular forces.
• What is the effect of molecular mass on boiling points with van der Waals forces?

  With van der Waals forces, boiling points generally increase with molecular mass.
• How does hydrogen bonding buck the trend of boiling points?

  Hydrogen bonding can lead to higher boiling points than expected based on molecular mass alone.
• What is the role of lone pairs in hydrogen bonding?

  Lone pairs on electronegative atoms can attract hydrogen atoms from other molecules.
• How does the arrangement of atoms affect hydrogen bonding strength?

  The bonding is strongest when the three atoms involved are in a straight line.
• What is the significance of the O-H bond length in hydrogen bonding?

  The internal O-H bond in the molecule is shorter than the dotted hydrogen bond connecting to another molecule.
• How does the tetrahedral structure form in water?

  The tetrahedral structure in water forms due to the presence of two hydrogen atoms and two lone pairs on the oxygen atom.
• How does hydrogen bonding affect the solubility of substances?

  Hydrogen bonding can increase the solubility of substances in water.
• What type of bond is formed between electronegative elements?

  Hydrogen bond
• Why is the hydrogen atom considered especially δ+ when attached to oxygen?

  Because it is bonded to the electronegative oxygen atom
• What happens to the lone pair on the oxygen atom in a hydrogen bond?

  It is attracted closely to the hydrogen atom of another molecule
• When is the bonding strongest in a hydrogen bond?

  When the three atoms are in a straight line
• How many lone pairs does oxygen have in a water molecule?

  Two lone pairs
• What type of structure is formed by hydrogen bonding in water?

  A tetrahedral hydrogen-bonded structure
• What is the effect of hydrogen bonding on boiling temperature?

  It increases the boiling temperature
• How do intermolecular forces affect melting and boiling temperatures?

  They increase with the strength of intermolecular forces
• How does hydrogen bonding in water differ from van der Waals forces?

  Hydrogen bonding is stronger than van der Waals forces