EL8 Flashcards
(23 cards)
What are some characteristics of s-block metals?
- soft
- weak
- low melting points
- very reactive with water and oxygen
Can the s-block metals be found naturally in their elemental form?
No because they are too reactive.
What is the first ionisation enthalpy?
The energy needed to remove one electron from every atom (in one mole of isolated gaseous atoms of the element).
What is general equation for the first ionisation process?
X(g) → X+(g) + e-
Which electron does the ionisation remove?
One of the outer shell electrons
Which elements have high first ionisation enthalpies?
Group 0 elements - as they are difficult to ionise and are very unreactive.
Which elements have low first ionisation enthalpies?
Group 1
Why does the first ionisation enthalpy decrease as you go down a group?
- More filled shells of electrons between outermost electron and nucleus.
- These shield the nucleus from the outermost electron
- This decreases the attraction between nucleus and outermost electron.
- So it is easier to remove the outermost electron
What does second, third, fourth etc ionisation enthalpies mean?
Energy required to remove one electron.
What is the general equation for the second, third, fourth etc ionisation processes?
X+(g) → X2+(g) + e-
X2+(g) → X3+(g) + e- (and so on)
What is the formula for group 1 metal oxides?
M2O
What is the general equation for the reaction of group 2 elements with oxygen?
2M(s) + O2(g) → 2MO(s)
What is the general equation for the reaction of group 2 elements with water?
M(s) + 2H2O → M(OH)2(aq) + H2(g)
What is the general equation for the decomposition of group 2 carbonates?
MCO3(s) → MO(s) + CO2(g)
What is the trend for the decomposition of group 2 carbonates?
The carbonates become more difficult to decompose down the group.
How does thermal stability change in group 2?
Thermal stability increases down the group.
What is charge density?
A measure of the concentration of charge on the cation.
Why does thermal stability change in group 2?
- The smaller the 2+ ion, the higher the charge density.
- Cations with a higher charge density can polarise the negative charge around the carbonate ion.
- This makes it less stable and easier to break up when heated.
What is the trend in reactivity of group 2 metals with water?
Increases down the group
What is the trend in thermal stability of group 2 carbonates?
Decomposes at increasingly higher temperatures down the group.
What is the trend in pH of group 2 hydroxides in water?
pH increases down the group
What is the trend in solubility of group 2 hydroxides?
Solubility increases down the group
What is the trend in solubility of group 2 carbonates?
Solubility decreases down the group
