State the two factors required for successful collisions to occur. Activation energy and correct collision geometry

Transcription

1 1 State the two factors required for successful collisions to occur Activation energy and correct collision geometry 2 State the definition of activation energy The minimum kinetic energy for successful collisions to occur 3 Name the intermediate structure formed when a successful collision occurs Activated complex 4 Describe the effect of increasing temperature on reaction rate Increases the rate of a reaction 5 Describe the effect of decreasing surface area on reaction rate Decreases the rate of a reaction 6 Explain why reaction rate increases when concentration increases Increasing the number of particles in a volume of space increases the likelihood of successful collisions

2 7 Explain why reaction rate decreases when pressure decreases Decreasing pressure increases the space between particles decreasing the likelihood of successful collisions 8 Write the equation used to calculate relative rate Relative rate (s -1 ) = 1/t Describe what is shown by an energy distribution diagram The number of particles with various kinetic energies and the number of particles that have overcome the activation energy Describe all the information that can be obtained from a potential energy diagram the potential energy of products/reactants, enthalpy change, activation energy of the forward/reverse reaction, exo or endothermic State the definition if a catalyst Provide an alternative reaction pathway with a lower activation energy 12 Describe the effect adding a catalyst has on the potential energy diagram The peak of the curve will be lowered

3 13 14 Explain the trend in covalent radii across a period Decreases across a period due to an increase in nuclear charge Explain the trend in covalent radii down a group Increases down a group due to an increase in the number of electron shells and shielding occurs 15 State the definition of electronegativity The ability of an atom to attract electrons Explain the trend in electronegativity down a group Decreases down a group due to an increase in the number of electron shells and shielding occurs Explain the trend in electronegativity across a period Increase across a period due to an increase in nuclear charge 18 Name the element which has the highest electronegativity Fluorine

4 19 State the definition of ionisation energy The energy required to remove one mole of electrons from one mole of atoms in the gaseous state Explain the trend in ionisation energy across a period Increase across a period due to an increase in nuclear charge Explain the trend in ionisation energy down a group Decreases down a group due to an increase in the number of electron shells and shielding occurs 22 Write the equation for the first ionisation of sodium Na(g) Na + (g) + e Write the equation for the second ionisation of sodium Na + (g) Na 2+ (g) + e - Explain why the first ionisation energy of lithium is much lower than the second First ionisation energy removed an outer electron from an unfilled shell, second ionisation energy removes an electron from a full shell

5 25 Name the three types of intramolecular bonds Non-polar covalent, polar covalent and ionic 26 Describe how a polar bond is formed A difference in electronegativity between two non-metal atoms results in partial charges being formed 27 Indicate the partial charges on a C-N bond partially positive carbon, partially negative nitrogen Describe how a non-polar bond is formed Electrons are shared equally between two non-metal atoms with the same electronegativity Explain why a C-O bond can be describe as having more ionic character when compared to a C-Cl bond there is a greater difference in electronegativity between C-Cl Explain why a N-Cl bond can be describe as having more covalent character when compared to a N-O bond there is a smaller difference in electronegativity between N-Cl

6 31 Name the three elements and two compounds that can form a covalent network Carbon, silicon, boron, silicon oxide, silicon carbide 32 Describe the properties associated with a covalent network high melting point and boiling point, does not conduct electricity 33 State which type of element would form the negative ion in an ionic bond non-metal elements 34 Name the three types of intermolecular bonds London dispersion forces, hydrogen bonding and permanent dipole-permanent dipole State the definition of London dispersion forces Forces of attraction that can occur between all atoms and molecules due to temporary/induced dipoles Describe the relationship between the size of atom or molecule and strength of London dispersion forces as an atom or molecule increases the strength increases

7 37 Explain how permanent dipole- permanent dipole interactions are formed Partial charges of a polar bond in a molecule can be electrostatically attracted to the partial charges of a polar bond in another molecule Explain how hydrogen bonds are formed When hydrogen is bonded to a highly electronegative atom, partial charges are formed. These can be electrostatically attracted to the partial charges in another molecule List the intermolecular bonds in order of strength (strongest to weakest) Hydrogen bonding, permanent dipolepermanent dipole, London dispersion forces Describe the effect of hydrogen bonding on the viscosity of a liquid The viscosity increases when hydrogen bonding is present Describe the relationship between the strength of intermolecular forces and melting point As the strength increases, the melting point increases Describe the relationship between the type of intramolecular bonds present and solubility Polar and ionic compounds will dissolve in polar solvent, non-polar compounds will dissolve in non-polar solvents (like dissolves like)

8 43 Describe the relationship between viscosity and the strength of intermolecular bonding As the strength increases, the viscosity increases 44 Describe why carbon dioxide is a non-polar molecule the polar bonds cancel each other out 45 Explain why CF4 is more soluble in water than CHF3 CHF3 is a polar molecule and CF4 is non-polar as the polar bonds cancel each other out Explain why NH3 has a higher boiling point than NCl3 NH3 is a polar molecule that has strong hydrogen bonds between molecules, NCl3 is non-polar and only has weak Ldfs Explain why graphite has a higher melting point than fullerene (C60) Intermolecular forces require less energy to break than intramolecular bonds in a covalent network (graphite) 48 Describe the relationship between viscosity and the number of hydroxyl groups As the number of hydroxyl groups increases, the viscosity increases

9 49 Describe how an ionic bond is formed Electrons are taken from an atom with low electronegativity to an atom with high electronegativity, creating charged particles 50 Describe the structure of an atom nucleus containing positive protons and neutral neutrons with outer energy levels/ electron shells containing negative electrons