Group 2 Flashcards
What is the appearance of Group 2 elements?
They are all metals with a shiny silvery-white appearance.
Where are Group 2 elements found in nature?
Their compounds are found in the Earth’s crust, mainly in rock structures.
What are the most common Group 2 metals?
Calcium and magnesium are the most common, while strontium and barium are less common, and beryllium and radium are rare.
Why are Group 2 elements called alkaline earth metals?
The name comes from their metal oxides, which were historically called “earths” because they were insoluble in water and did not decompose on heating
Who first predicted that ‘earths’ were metal oxides?
Antoine Lavoisier predicted it in 1789, and Sir Humphry Davy later confirmed it by extracting metals through electrolysis
How many electrons do Group 2 elements have in their outer shell?
They have two electrons in their outermost s sub-shell.
What happens to atomic radius as you move down Group 2?
The atomic radius increases because each successive element has an additional electron shell, which shields the outer electrons from the nuclear charge.
Why does first ionisation energy decrease down Group 2?
Extra electron shells shield the outer electrons from the nuclear charge, making it easier to remove an electron
What trend is observed in the melting points of Group 2 elements?
The melting points generally decrease down the group, though magnesium has an unexpectedly low melting point.
What is the trend in solubility of Group 2 sulfates?
The solubility of Group 2 sulfates decreases down the group.
Why is barium sulfate used in medical imaging?
It is insoluble, so it passes through the body without dissolving in fluids, allowing X-rays to capture images of the digestive tract.
What is Milk of Magnesia and what is it used for?
Milk of Magnesia is an 8% suspension of magnesium hydroxide used for digestive upsets and as a laxative.
How does magnesium hydroxide neutralize stomach acid?
It reacts with hydrochloric acid to form magnesium chloride and water:
Mg(OH)₂(s) + 2HCl(aq) → MgCl₂(aq) + 2H₂O(l)
Why is calcium hydroxide used in agriculture?
It neutralizes soil acidity, improving crop growth and yield.
What is the Kroll process used for?
It is used to extract titanium from titanium(IV) chloride using magnesium as a reducing agent.
Why is titanium difficult to extract?
Reduction with carbon forms brittle titanium carbide, and other reduction methods result in impurities that are difficult to remove.
How can sulfate ions be identified in a solution?
By adding barium chloride solution. A white precipitate of barium sulfate forms if sulfate ions are present.
Why is acid added before testing for sulfate ions?
To remove any carbonate ions, which could also form a white precipitate and give a false positive result.
