Inorganic chemistry and the periodic table; IONISATION Flashcards
(15 cards)
what is ionisation energy?
minimum amount of energy needed to remove 1 MOLE OF ELECTRONS from 1 MOLE OF ATOMS in the GASESOUS state
what is the definition of the FIRST ionisation enthalpy and what do they form?
energy needed to remove 1 ELECTRON from EACH ATOM in 1 MOLE of gaseous atoms–> to form 1 mole of gaseous 1+ ions
what is an example equation of a first ionisation enthalpy?
O(g)–> O+(g) + e-
what are the key points for ionisation enthalpies?
-must have state symbol gas (g)
-Always refer to 1 mole in the defintion
-the lower the ionisation enthalpy –>easier to remove the OUTER electron and from an ion
-always endothermic–>always postitive values
what 3 things effect the ionisation enthalpies?
-electron sheilding
-nuclear charge
-atomic size/radius
how does the factor electron sheilding influence ionisation enthalpy?
-more electron shells between positive nucleus and negative electron being removed –>weaker attraction–>lower energy required to remove electron–> lower ionisation enthalpy
how does the factor nuclear charge influence ionisation enthalpy?
more protons+positive charge in nucleus–> stronger attraction betweeen nucleus and outer electron–>more energy required to remove elctron–>higher ionisation enthalpy
how does the factor atomic size influence ionisation enthalpy?
bigger the atom–>outer elctrons are further away from nucleus–>due to more sheilding–>weaker attractive force–>less energy required to remove electron–> lower ionisation enthalpy.
explain the ionisation trend for atomic size going down group 1/2.
atomic radius increases–> number of electrons increase+ OUTER electrons are further from the nucleus–>weaker force of attraction–>energy required to remove electron DECREASES down groups.
explain the ionisation trend for sheiding going down group 1/2.
sheilding increases down the group–>more shells filled with electrons–>less nucelar attraction–>weaker force of attraction–>energy required to remove electron DECREASES down the group
for groups, why is there no increase in ionisation enthalpy?
Although there is an increase in proton number–>does not lead to increase in ionisation enthalpy–>sheilding +atomic size are MORE IMORTANT factors
what is the trend for ionisation enthalpy across periods for nuclear charge?
ionisation increases across periods–>elements are in order of proton number which increases along–>increases nuclear charge–>increased attraction between positive nucleus +outer electron
what is the trend for ionisation enthalpy across periods for sheilding+atomc radius?
ionisation STLL increases –> becauses outer shell electrons are roughly at the same level–>just a little extra sheileding and distance–>attraction lessened a littlebit BUT nuclear charge prioritises.
explain ionisation enthalpy for s block elements
low first ionisation comapred to different elements in different blocks–>low nuclear charge as genral lower number of protons on left side of peridoic table –>s block =more reactive
explain ionisation for elements in the p block
higher first ionisation–>increase in number of protons in right side/across the period–>more difficult to loose outer electron.
