Halogens & Halides Flashcards
What happens to the electronegativity when descending group 2?
Decreases due to more shielding between the positive nucleus and outer shells thus bonded pairs of electrons are less strongly held
What happens to the melting point down group 2?
Decreases due to size of the atom increasing but the charge remains the same
What is the general reaction between Group 2 metals and water?
Metal + Water = Metal Hydroxide + Hydrogen
What happens to the intensity of the reaction as you go down group 2?
Increases, as first ionisation energies decrease so electrons are easily removed.
What 2 factors governs the intensity of group 2 elements with water?
1) How easily electrons are removed
2) How soluble the Hydroxides are
What is trend in solubility of sulphates down group 2?
Decreases
Which group 2 elements + sulphuric acid or sodium sulphate produce a white precipitate?
Ca, Sr and Ba
What is the test for sulphate ions?
BaCl (aq) + HCl + unknown solution
A thick white precipitate that does not dissolve is dilute HCl indicates sulphate or hydrogen sulphate ions are present
What is the purpose of the HCl when testing for sulphate ions?
To remove any other ions such as Carbonate or Hydroxide ions
What is the trend in solubility of hydroxides down group 2?
Increases
Which group 2 ion reacts with sodium hydroxide to produce a white precipitate?
Magnesium
Which group 2 ion forms a faint white precipitate when reacted with excess sodium hydroxide?
Calcium
What are the uses of metal hydroxides?
MgOH2= used to reduce indigestion CaOH2= neutralises acidic soil and lakes
What is the trend in melting and boiling point down group 7?
Increases due to an increase in the number of VDW forces between molecules
What is the test for halide ions?
1) Addition of dilute nitric acid
2) Addition of silver nitrate solution
