s-block (gp 1)

Question 1

Why are their MP, BP and enthalpy changes relatively low compared to other metallic elements?

Answer 1

weak metallic bonding in the lattices. They have lower densities than other metals because of their large atomic radii.

Question 2

their effcetive nuclear charge is ___, becuase

Answer 2

low, the large 1s orbital is very good at shielding, this is why they are very reactive

Question 3

why are they stored in oil

Answer 3

they react with water and oxygen

Question 4

how are sodium and lithium obtained

Answer 4

electrolysis of thier molten chlorides (redox)

Question 5

how are potassium, rubidium and caesium prepared

Answer 5

reduction of thier molten salts with sodium at high temperatures

Question 6

what is the best group 1 reducing agent (best at being oxidised)

Answer 6

francium

Question 7

down the group, the ionisation energy ____

Answer 7

decreases, due to increased shielding

Question 8

what is the downs cell

Answer 8

used to obtain Na from NaCl. CaCl2 is added to run the cell lower than the melting point.

Question 9

lithium burns with O to make

Answer 9

Li2O

Question 10

sodium burns with O to make

Answer 10

Na2O2 (peroxie)

Question 11

potassium and the heavier metals burn with O to make

Answer 11

MO2 (superoxide)

Question 12

are group 1 acidic or basic

Answer 12

basic

Question 13

write the reaction between a superoxide annd water (K), what type of reaction is this

Answer 13

4KO2 + 2H2O -> 4KOH + 3O2
disproportionation - O2- is being ox to O2 and red to OH-

Question 14

show the hydration reaction

Answer 14

-> MOH + H2

Question 15

lithium, sodium and potassium are ___ dense than water

Answer 15

less (float on top)

Question 16

what is the chloroalkali process

Answer 16

preparing NaOH through the electrolysis of sodium chloride.
2NaCl + 2H2O -> 2NaOH + H2 + Cl2

Question 17

how to make a gp1 halide

Answer 17

the reaction of the carbonate (CO3) or the hydroxide, with the appropriate hydrohalic acid (H+halogen)

Question 18

what are the biproducts of making a gp1 halide

Answer 18

water and carbon dioxide

Question 19

they also react with ethyne (what is this?)

Answer 19

C2H2 (acetylene) trilple bonded CC

Question 20

what is the catalyst for making ethynides

Answer 20

liquid NH3

Question 21

what is the only stable binary nitride, why?

Answer 21

Li3N, high lattice enthalpy, due to the small size of the Li+ cation.

Question 22

OXANIONS,
MNO3 decomposes to …
(not lithium)

Answer 22

MNO2 + O2

Question 23

whats differnent about the decomposition of LiNO3

Answer 23

makes Li2O + NO + O2

Question 24

why is decompositionn less favoured

Answer 24

decrease in the difference between the lattice enthalpies of nitrate and nitrite.

Question 25

what does lattice enthalpy mean

Answer 25

the energy change when one mole of a solid ionic compound is formed from its gaseous ions

Question 26

what is the trend down the group for the stability when bonded to small anions (hydride and nitrides)

Answer 26

less stable, decrease in lattice enthalpy

Question 27

for salts containing large anions, the solubility ____ down the group (clorides, bromides, iodides, nitrates) (small would be fluorides and hydroxides)

Answer 27

decreases

Question 28

as a general rule, compouds with ____ anions and ____ cations are soluble.

Answer 28

small, large / large, small

Question 29

metal ions are lewis ____

Answer 29

acids

Question 30

what is differnent about the reaction with ammonia

Answer 30

ammonia isnt being reduced, the metal atoms ionize to form cations and electrons.

Question 31

what colour does the reaction with ammonia turn

Answer 31

dark blue

Question 32

why is the colour of the ammonia reaction independent of the solvent used?

Answer 32

presence of the solvated (free) electrons, so they are easily oxidised (loss of electrons)