11. Group II Elements Flashcards
(25 cards)
Why are group II elements known as s-block elements?
Their outer shell (highest energy) electrons are in an s subshell.
Why isn’t beryllium studied in detail at AS?
Its chemistry is unusual.
Describe the trend in electronic configuration from Mg to Ba.
The atoms of all these elements have an electronic configuration that ends in s2.
Describe the trend in atomic radius from Mg to Ba.
It increases down the group as the outer shell electrons are further from the nucleus.
Describe the trend in first ionisation energy from Mg to Ba.
It decreases, as atomic radius and shielding by inner electrons both increase.
What does the letter M represent in general equations?
A group II metal
for reactions with oxygen, water/steam, and dilute mineral acids
How does reactivity change down the group?
It increases
How does M react with oxygen?
When heated in air, M reacts. In pure oxygen, it reacts more vigorously.
The metal burns, producing a specific flame colour, and then forms a white powder (M oxide)
How does M react with water or steam?
Mg is slow with water but reacts readily with steam. The others react readily with water.
What are the observations of M reacting with water?
Ca/Ba/Sr: heat and bubbles, metal disappears, colourless solution formed
Ca: less soluble Ca(OH)2 can cause milky solution. Ca sinks and rises due to hydrogen release.
What is the apparatus for reacting M with water?
A beaker of water. Metal inside covered with a full and overturned funnel, leading to an overturned boiling tube mostly filled with water.
What are the observations of M reacting with steam?
Mg burns with bright white light and the others with increasing vigour and characteristic flames, all producing white powder.
What is the apparatus required to react M with steam?
Damp mineral wool and metal in a horizontal boiling tube, with heat applied. Delivery tube leading to trough of water with beehive shelf leading to gas jar mostly filled with water.
What are the observations of M reacting with dilute hydrochloride and sulfuric acid?
Heat and bubbles, metal disappears, colourless solution formed
What are the observations of reacting M with nitric acid?
Brown gas (nitrogen dioxide) given off as well as other observations, because nitrogen in nitric acid is easily reduced
Describe the ‘basic’ nature of group II oxides.
Group II metals are basic, and form basic oxides, which act as proton acceptors and can accept H ions from acids or water.
What are the observations when MO reacts with water?
Heat released, solid expands/crumples, reaction hisses, colourless solution formed.
M(OH)2 formed
What are the observations when MO reacts with dilute mineral acids?
Some reactions require warming but all group II metal oxides react with dilute mineral acids to form salt and water.
Heat released, solid disappears
What is the trend in solubility of sulfates down the group?
Solubility of sulfates DECREASES down the group.
Sulfates suffer, I dunno
What is the trend in solubility of hydroxides down the group?
Solubility of hydroxides INCREASES down the group.
Hydroxides have a great time, I dunno 😂
What is thermal stability?
How stable it is to heat and whether it will decompose on heating. Depends on the charge density of the cation and the ability of the cation to polarise and destabilise the anion.
What is the trend in thermal stability of carbonates down the group?
Thermal stability of carbonates INCREASES down the group. More energy is needed to decompose the lower-down ones.
How can the trend in thermal stability of carbonates down the group be explained?
Metal cation size increases down the group.
Charge density of the cation decreases down the group.
Descending, the cation is less able to polarise and destabilise the carbonate ion.
More energy required to decompose further down.
What is the trend in thermal stability of hydroxides going down the group?
Thermal stability of hydroxides INCREASES down the group, similar to carbonates.
