2I-Group 2, Alkaline Earth Metals Flashcards
Trend in electronegativity down group 2 Mg-Ba
Decrease, less energy needed to remove valence electrons as they become further from nucleus, number of protons increase but due to shielding effect don’t have a strong attraction to valence electrons
Trend of atomic radius down group 2 Mg-Ba
Increases, has a whole extra energy level below it
Trend in melting points down group 2 Mg-Ba
Decrease from Ca, sea of delocalised electrons further from +ve nuclei, strength of metallic bond decreases
Melting points are high due to giant metallic structures
Reactions of Mg-Ba with water (l) and (g) and observations for each
More reactive going down the group
Metal + water (l) —> metal hydroxide + hydrogen
Fizzing, metal dissolves
Metal + water (g) —> metal oxide + hydrogen
White flame, white light
Why is magnesium used to extract titanium from TiCl4
Metal oxides found in earth are usually reacted with carbon but titanium reacts with it forming titanium carbide
Titanium oxide reacts with chlorine and carbon forming titanium chloride and carbon monoxide, this is then reduced with magnesium
Trend in solubility down group 2 for hydroxides in water
Increase in solubility
Mg(OH)2 is sparingly soluble, low solubility
How is Mg(OH)2 used in medicine
Milk of magnesia, treats indigestion as it neutralises excess stomach acid causing heartburn
How is Ca(OH)2 used in agriculture
Slaked lime treats acidic soil, allows crops that need to grow at higher pH’s to thrive
How does CaO or CaO3 remove SO2 from flue gas
CaO reacts with sulphur dioxide forming calcium sulphite and water
Prevents pollutants being released into atmosphere as it causes acid rain
Trend in solubility down group for sulphates in water
Decreases
BaSO4 is insoluble
How is barium sulphate used in medicine
Insoluble can be taken as a barium meal, outlines the gut in X-ray
How does barium chloride test for sulphates
Add HCL to remove carbon dioxide so only one white precipitate forms then barium chloride, colourless to white precipitate if sulphate is present
Use sulphuric acid to test for Ba ions, forms a white ppt
