EL 8 - Spectacular metals

Question 1

What is ionisation enthalpy?

Answer 1

the minimum amount of energy required to remove an electron (in the outer shell)

Question 2

What is the first ionisation of calcium (general equation)?

Answer 2

Ca(g) -> Ca^+(g) + e^-

Question 3

What is the second ionisation of calcium (general equation)?

Answer 3

Ca^+(g) -> Ca^2+(g) + e^-

Question 4

Do elements (from group 1 and 2) get more or less metallic down the group?

Answer 4

More metallic down a group - they more readily form cations in ionic compounds
This is why elements at the bottom of Group 1 and 2 are most reactive

Question 5

Do elements (from group 1 and 2) get more or less metallic across a period - left to right?

Answer 5

Less metallic across a period

Group 1 metals are more reactive than the Group 2 metals in the same period

Question 6

What are the usual properties of s-block metals?

Answer 6

Soft, weaker metals with low melting points, very reactive with water and oxygen

Question 7

Does ionisation energy increase or decrease across a period? Explain why

Answer 7

Ionisation increases across a period.
This is because there are more electrons being added to the outer shell and more protons in the nucleus. Therefore, the nuclear charge becomes more positive, electrons will be held more tightly and so it gets harder to pull one from the outer shell (this is an example of periodicity)

Question 8

As the s-sub-shell is lower in energy than the p-sub-shell does it mean more or less energy is needed to remove an electron?

Answer 8

Less energy is needed to remove an electron

Question 9

What is the trend of the first ionisation enthalpies down a group? Explain why

Answer 9

The first ionisation enthalpies decrease as you go down a group.
Reason: The attraction between the nucleus and the outermost electron decreases. There are more filled shells of electrons between the nucleus and the outermost e-, reducing the attraction the e- experiences. So it is easier for the outermost e- to be removed

Question 10

In Group 1 and 2, what is the relation between reactivity and first ionisation energies?

Answer 10

The metals of Group 1 and 2 react by losing their outer e- so the first ionisation energy trends also correspond to an increase in reactivity down the group

Question 11

What are successive ionisation enthalpies?

Answer 11

The energy required to remove further electrons

Question 12

What is the second ionisation enthalpy?

Answer 12

The energy required to remove one electron from a X^+(g) ion. (Not the energy required to remove two e- from as X(g) atom)
* X represents any element

Question 13

Give the general equation of all Group 2 elements reacting with oxygen

Answer 13

2M(s) + Ov2(g) -> 2MO(s)

*M: any typical Group 2 element

Question 14

Give the general equation of a typical Group 2 metal metal reacting with water

Answer 14

M(s) + 2Hv2O(l) -> M(OH)v2(aq) + Hv2(g)

*M: any typical Group 2 element

Question 15

Describe the general equation of heating a typical Group 2 metal carbonate

Answer 15

MCOv3(s) -> MO(s) + COv2(g)

*M: any typical Group 2 element

Question 16

Which will decompose first calcium carbonate or magnesium carbonate?

Answer 16

Mg carbonate: easily decomposes (over a bunsen flame in a test tube)
Ca carbonate (limestone): needs much stronger heat before it decomposes

Question 17

What is the decomposition of Ca carbonate (limestone) used for?

Answer 17

Manufacturing calcium oxide (quicklime)

Question 18

Explain the change in thermal stability in terms of the charge density of cations. Use the example of a group 2 carbonate.

Answer 18

Cations with a higher charge density (those at top of Group 2) can distort or polarise (split) the negative charge cloud around the carbonate ion making it less stable and easier to break up on heating

Question 19

What is the link between the size of the ion and its charge density?

Answer 19

The smaller the ion the higher the charge density

Question 20

What is formed when oxides hydroxides react with acids?

Answer 20

salt + water

Question 21

What is the trend in reactivity with water going down group 2?

Answer 21

Increasing in reactivity

Question 22

What is the trend in thermal stability of carbonate going down group 2?

Answer 22

Decomposes at a higher temperature

Question 23

What is the trend in pH of hydroxide in water going down group 2?

Answer 23

Increasing pH

Question 24

What is the trend in solubility of hydroxide going down group 2?

Answer 24

Increasing solubility

Question 25

What is the trend in solubility of carbonate?

Answer 25

Decreasing solubility