exam review Flashcards
theory behind Boron only requiring 6 electrons
- stability with half-filled 2p orbital in boron’s electrons promotes tendency to form compounds.
If it was to follow the octet rule, 2p would be unfilled which would be very unstable - also it doesn’t have enough electrons to fulfill the octet rule
temperature vs heat
heat is the transfer of thermal energy from one object to another
thermal energy
the total quantity of kinetic and potential energy in a substance
temperature
a measure of the average kinetic energy of entities in a substance
properties of coordinate covalent bonds
- very hard due to strong covalent bonds in the lattice structure
- high, strong bonds make it difficult and break strong covalent bonds
- generally insoluble in any solvent (huge molecules)
- no IMF
what does the energy level diagram look like when an element is in its excited state
- 1 e- promotion to the next energy level,
why fill 3D and leave 4S
- a filled d shell is more stable than a filled s shell, more energy
expanded octet logic
- uses a nearby d sub shell allowing for more room in the valance shell
pick a scientist and explain their contribution to the atomic theory
Ernest rutherford:
- gold foil experiment
Rutherford fired alpha particles (positively charged helium nucleus) at a gold foil sheet that would be detected on a screen
- most passed straight through (showed atoms had empty space)
- some were deflected an angles
- some reflected back
- therefore, the positive charge had to be in the centre
problems: - said that electrons would be moving in circular motion which would mean they would have to be emitting energy and wouldn’t be stable
- didn’t explain how electrons would be kept from falling into the nucleus
explain the common ion effect
The common ion effect occurs when the presence of an ion in a solution reduces the solubility of a salt containing that ion.
This happens because adding more of an ion that is already present in a solution shifts the equilibrium towards the formation of the solid precipitate, reducing the concentration of ions in the solution and decreasing solubility.
use le chateliers principle to explain weak acid strong base titration
The weak acid partially dissociates into its ions (H⁺ and A⁻), while the strong base completely dissociates into its ions (Na⁺ and OH⁻).
As the strong base is added to the weak acid solution, it reacts with the weak acid to form water and the conjugate base of the weak acid (A⁻). According to Le Chatelier’s principle, adding more of the strong base (OH⁻ ions) will shift the equilibrium of the weak acid dissociation reaction to the right, favoring the formation of more ions (H⁺ and A⁻) and water.
As a result, the concentration of H⁺ ions in the solution increases, leading to a decrease in the pH of the solution. The pH continues to decrease until the equivalence point is reached, where all the weak acid has been neutralized by the strong base.
At the equivalence point, the solution contains only the conjugate base (A⁻) of the weak acid and the cation (Na⁺) from the strong base. The pH at the equivalence point depends on the nature of the conjugate base formed and the concentration of the resulting solution.
After the equivalence point, any additional strong base added will result in an increase in the pH of the solution, as the excess OH⁻ ions react with water to form more OH⁻ ions, increasing the concentration of hydroxide ions in the solution.
q vs enthalpy
q is the amount of heat transferred to a system whereas H is used to describe the change in enthalpy, which is the total heat of system
units
enthalpy - J/mol
q-J
standard enthalpy- kJ
molar enthalpy- kJ/mol
