EL8 + EL9

Question 1

trends in s-block elements

Answer 1

more metallic/reactive down a group, more readily form cations in ionic compounds
less metallic/reactive across a period
soft, weak metals with low MPs
too reactive with water and oxygen to have many uses
form very useful and important compounds

Question 2

1st ionisation enthalpy

Answer 2

energy required to remove one electron from every atom in one mole of isolated, gaseous atoms of the element

Question 3

as you go across a period, 1st ionisation enthalpy

Answer 3

increases
more difficult to remove an electron
more electrons in the outer shell but also more protons being added to the nucleus, so electrons held more tightly

Question 4

as you go down a group, 1st ionisation enthalpy

Answer 4

decreases
attraction between nucleus and outermost electrons decreases
more filled electrons between nucleus and outer shell shielding charge of nucleus

Question 5

trends in group 2 elements and compounds - reactivity with water

Answer 5

reactivity increases down group

due to shielding effect of electron shells

Question 6

trends in group 2 elements and compounds - thermal decomposition

Answer 6

becomes more difficult as you descend the group

more reactive elements at bottom of group prefer to be in compounds

Question 7

trends in group 2 elements and compounds - lattice enthalpy (endothermic)

Answer 7

as you descend the group, less energy is required to break bonds that hold the ions in a lattice together because interatomic distances are greater

Question 8

trends in group 2 elements and compounds - hydration enthalpy of ions (exothermic)

Answer 8

as you descend group, less energy is released from hydration of cation

Question 9

trends in group 2 elements and compounds - strength and solubility of oxides + hydroxides

Answer 9

stronger and more soluble at bottom of group

Question 10

trends in group 2 elements and compounds - strength and solubility of carbonates

Answer 10

stronger and more soluble at top of group

Question 11

acid

Answer 11

a compound that dissociates in water to produce protons

Question 12

base

Answer 12

compound that reacts with acids by accepting protons to produce water and a salt

Question 13

alkali

Answer 13

base that dissolves in water to produce hydroxide ions

Question 14

oxonium ion

Answer 14

when an acid is in a solution of water, a H3O+ ion forms