LAB 8 Flashcards
ionic radii will
increase down a group
- larger atoms with more ve further from the nucleus (occupying more orbitals)
ionization energy
decreases down a group
- energy required to remove 1 ve
electron affinity
- highest at the top of the group
- it decreases as you move down because the valence shell is further from nucleus, decreasing attraction
effect of increasing radii on solubility based on chemistry of alkaline earth metals
- no beryllium bc its salts are poisonous, no radium because its radioactive
- solubility refers to breaking down ionic lattice (energy in) and hydrating ions (energy out)
hydration enthalpy
energy released when one mole of ions in gas phase is dissolved in water
- larger hydrations energies released afford better solubility
Trend with hydration energy
decreases with increasing ionic radius
- increases with increasing change
Alkaline earth metals will (eqn)
M2+ precipitate in presence of anions
M2+ + X2- = MX(s)
Effect of electron affinity trend down the group
- elements at top of group are capable of removing electrons from anions lower down the group
- within group 17, we expect the following:
Cl- + 2Br- = 2Cl- + Br2
- chlorine is being reduced and bromide ion is oxidized
how are the reactions monitored
- observing the characteristic colours of halogens
- use water and heptane mixture to see this
what will halide anions form
-solvent solute ineractions (ion dipole) interactions with water and will b in aq layer
- elemental halogens prefer heptane solvent which is non-polar
- form strong solvent-solute interactions known as dispersion forces
water and heptane are
immiscible
- water is denser than heptane
- heptane will b on top
- colour of heptane will indicate which halogen is present
Fluorine is
very reactive and astatine is radioactive
Part C we will be
identifying an unknown alkali earth metal halide MX2
elements in the same group
exhibit similar properties and reactivity with small differences between neighbours within group
moving down group
n increases
