d-block elements Flashcards
what is a d-block element?
an element whose ‘outer’ electron is in a d-orbital
what is a transition element?
an element whose atom has an incomplete d-sub-shell, and/or which can give rise to cations with an incomplete d-subshell
what is aufbau principle?
- Fill orbitals in order of increasing energy.
- The 4s subshell is filled ‘conventionally’ before the 3d subshell – this is more so because the 4s is more penetrating cf. 3d rather than because it is lower in energy.*
which are the 2 exceptions to aufbau’s principle?
chromium + copper
(1 in 4s before filling 3d)
which group of d-block elements are not considered transition metals? why?
- group 12
- do not have partly filled d-orbitals AND do not form any stable cations with partly filled d-orbitals
how do d-block elements melting and boiling points compare to group 1/2?
- higher melting and boiling points
- stronger metallic bonding due to stronger interactions between the more numerous delocalised electrons
how does the reactivity of d-block elements compare to those of group 1/2?
- less reactive
- form stronger metallic bonds
- have lower propensities to lose electrons and become charged
how are the ionisation energies of d-block elements?
relatively higher due to the poor shielding from the d-subshells and due to the more nuclear charge (more protons in nucleus)
why are d-block elements often used as catalysts?
exhibit variable oxidation states
define zeff
The positive charge experienced by the outer electron(s), taking into account shielding of other electrons
how do the atomic/ionic radii compare to group 1/2?
tend to be smaller
how do ionisation energies change across the firt row of d-block elements?
Gradual increase across the 1st row (observed for all periods).
