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IBChemistryDPHLFlashcardsWhat are the Mechanisms of Chemical Change?Electron Sharing Reactions

Electron Sharing Reactions (DP IB Chemistry)

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  • FrontRadicals

    What are radicals?

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  • What are radicals?

    Radicals are chemical species that have an unpaired electron.

  • Define the term atomic radical.

    An atomic radical is a single atom with an unpaired electron.

  • Define the term polyatomic radical.

    A polyatomic radical is a group of atoms bonded together with no overall charge, that contains an unpaired electron.

  • Define the term anionic radical.

    An anionic radical is an atom or molecule that gains one electron to become an anion and has one atom with an unpaired electron.

  • Define the term cationic radical.

    A cationic radical is an atom or molecule that loses one electron to become a cation and has one atom with an unpaired electron.

  • True or False?

    Radicals can exist independently of the charge on the chemical species.

    True.

    Radicals can exist independently of the charge on the chemical species.

  • What is the significance of the unpaired electron in a radical?

    The unpaired electron in a radical makes them highly reactive, as it causes them to have a high enthalpy.

  • How are radicals indicated in chemical formulas?

    Radicals are indicated by the dot (•) in the formula of the chemical species.

  • What type of radical is C2H5OH+•?

    C2H5OH+• is a cationic and polyatomic radical.

  • True or False?

    Br• is an anionic radical.

    False.

    Br• is not an anionic radical, it is an atomic radical.

  • When the radical is made of several atoms, the radical dot should be shown on the atom with the ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ ‎ electron.

    When the radical is made of several atoms, the radical dot should be shown on the atom with the unpaired electron.

  • What is homolytic fission?

    Homolytic fission is the breaking of a covalent bond in such a way that each atom takes an electron from the bond to form two radicals.

  • True or False?

    Homolytic fission is an exothermic process.

    False.

    Homolytic fission is an endothermic process, as bond breaking requires energy.

  • What type of arrow is used to show the mechanism of homolytic fission?

    A single-headed curly arrow / fish-hook / half curly arrows are used to show the mechanism of homolytic fission.

  • What condition is required for the homolytic fission of a Cl2 molecule?

    Ultraviolet light or heat is required for the homolytic fission of a Cl2 molecule.

  • State the equation for the homolytic fission of a bromine molecule.

    The equation for the homolytic fission of a bromine molecule is:

    Br2 rightwards arrow with blank on top Br• + Br• 

  • Draw the mechanism for the homolytic fission of a Cl2 molecule.

    The mechanism for the homolytic fission of a Cl2 molecule is:

    Homolytic fission of a Cl2 molecule

  • What is thermolytic fission?

    Thermolytic fission is the homolytic fission of weaker bonds that can be achieved by simply heating the compound.

  • What is photolytic fission?

    Photolytic fission is the homolytic fission of stronger bonds, such as halogen bonds, that requires exposure to high-energy UV light.

  • Why are alkanes relatively stable and unreactive?

    Alkanes are relatively stable and unreactive due to the strength of the C-C and C-H bonds and their non-polar nature.

  • True or False?

    Alkanes only react in combustion reactions and undergo substitution by radicals.

    True.

    Alkanes only react in combustion reactions and undergo substitution by radicals.

  • What is the role of UV light in the free-radical substitution reaction of alkanes?

    UV light is required to provide the energy needed to initiate the homolytic fission of the halogen-halogen bond, which is the first step in the free-radical substitution reaction of alkanes.

  • What is the purpose of the initiation step in the free-radical substitution of alkanes?

    The purpose of the initiation step in the free-radical substitution of alkanes is to form the initial radicals that will propagate the chain reaction.

  • True or False?

    Only one product is formed during a termination step.

    False.

    Multiple products can be formed during a termination step.

  • What occurs during the termination step in free radical substitution?

    In the termination step the chain reaction ends due to two free radicals reacting together and forming a single, unreactive molecule.

  • Write two equations for the propagation steps for the reaction between chlorine and ethane in the presence of ultraviolet light.

    Two equations for the propagation steps for the reaction between chlorine and ethane in the presence of ultraviolet light are:

    Cl● + CH3CH3 → CH3CH2●  + HCl

    Cl2 + CH3CH2● → CH3CH2Cl + Cl●

  • What is the product of the termination step between two CH3CH2● free radicals?

    The product of the termination step between two CH3CH2● free radicals is: CH3CH2CH2CH3.

  • What is the problem with the free-radical substitution of alkanes for preparing specific halogenoalkanes?

    The free-radical substitution of alkanes is not very suitable for preparing specific halogenoalkanes, as a mixture of substitution products is formed.

Previous:Electron Transfer ReactionsNext:Electron Pair Sharing Reactions

    1. Topic 1

      Introduction to the Particulate Nature of Matter

    2. Topic 2

      The Nuclear Atom

    3. Topic 3

      Electronic Configurations

    4. Topic 4

      Counting Particles by Mass: The Mole

    5. Topic 5

      Ideal Gases

    1. Topic 1

      The Ionic Model

    2. Topic 2

      The Covalent Model

    3. Topic 3

      The Metallic Model

    4. Topic 4

      From Models to Materials

    1. Topic 1

      The Periodic Table: Classification of Elements

    2. Topic 2

      Functional Groups: Classification of Organic Compounds

    1. Topic 1

      Measuring Enthalpy Change

    2. Topic 2

      Energy Cycles in Reactions

    3. Topic 3

      Energy from Fuels

    4. Topic 4

      Entropy & Spontaneity

    1. Topic 1

      How Much? The Amount of Chemical Change

    2. Topic 2

      How Fast? The Rate of Chemical Change

    3. Topic 3

      How Far? The Extent of Chemical Change

    1. Topic 1

      Proton Transfer Reactions

    2. Topic 2

      Electron Transfer Reactions

    3. Topic 3

      Electron Sharing Reactions

    4. Topic 4

      Electron Pair Sharing Reactions

    1. Topic 1

      Tool 1: Experimental Techniques

    2. Topic 2

      Tool 3: Mathematics