periodicity (inorganic I) Flashcards
group 3
what elements are in each block of the periodic table?
• s-block —> groups 1 & 2
• p-block —> groups 3 to 0
• d-block —> transition metals
• f-block —> radioactive elements
define ‘periodicity’
trends in physical & chemical properties of elements across the periodic table
what is the general trend for atomic radius across a period? why?
it decreases!
>increased no. of protons increases nuclear charge
>the elements have similar shielding
>larger nuclear attraction to outer electron
define ‘1st ionisation energy’
the enthalpy change needed for the removal electrons from each atom from of one mole of atoms of the element in the gaseous phase, forming positive ions
is ionisation endo or exo?
endothermic as it req. energy —> always a +ve value
what is the general trend for ionisation energy across a period? why?
it increases!
>increased nuclear charge
>electrons in same energy level
>elements have similar shielding
>larger nuclear attr. to outer electrons
reason for deviation in I.E from Mg to Al (& B & Ga)
group 2 —> group 3
> Al has outer electron in p sub-shell but Mg has outer electron in s sub-shell
electrons in p sub-shell = higher in energy than s sub-shell
Al electron in p lost more easily -> less energy needed to remove it
reason for deviation in I.E from P to S (& O & Se)
group 5 —> group 6
> S’ outer electron pairs up with 1st electron in p orbital
slight repulsion between electron pair
makes outer electron easier to remove
what affects the mp n bp of substances?
their bonding n struc.
Na, Mg, Al —> describe metallic bonding in relation to mp
high mp bc. of strong forces of attr. between +ve metal ions & sea of delocalised electrons —> lots of energy needed to overcome these
what is general trend of the mp/bp across the beginning of the period for the metallic substances? why?
their mp/bp increases!
>radius decreases but nuclear charge increases
>also more delocalised electrons
>stronger attr. between +ve metal ions & d. electrons
describe bonding in Si in relation to mp —> macromolecular substance
has very high mp (highest in period)
>has many strong, cov. bonds
>lots of energy needed to overcome these
describe the bonding in P4, S8, Cl2 —> simple, molecular substances
weak VDW forces between mols —> little energy needed to overcome these
why does S8 have a higher mp/bp than P4?
> larger mol
more electrons
more, stronger VDW forces
more energy needed to overcome these
bonding in Ar —> monoatomic, noble gas
very low mp —> weak VDW forces between ATOMS —> little energy needed to overcome these
