Lecture 14 (Main group elements, etc.) Flashcards
What does valence characterize?
the connectivity of chemical elements
What is de facto?
The number of electrons an element in a certain compound uses for bonding
What does oxidation state characterize?
The formal oxidation of chemical elements in compounds
What is the rules of oxidation state?
1) oxidation state of a free element is 0
2) monatomic ions have equal oxidation states to the net charge
3) H has a +1, O has a -2, H has -1 in metal hydrides, and O has a -1 in peroxides
4) sum of oxidation states equal to the net charge
What is coordination number independent of?
charge
What type of compounds allow for extreme oxidation states?
very electronegative elements (O and F)
Oxidation states that involved unpaired electrons are more stable. True or false?
False. “that are NOT involved”
What does weight mean with oxidation states?
Heavier elements will favour lower oxidation states, more than lighter elements from the same period.
What is d-block contraction?
The effect of the full 3d (3d10) orbitals on the period 4 elements Ga, Ge, As, Se and Br (post-transition elements), resulting in lower than expected radii and increased ionization potentials.
what is the reason for d-block contraction?
Poor shielding of the nuclear charge by the d electrons, resulting in a stronger attraction of the valence electrons by the nucleus
What is f-block contraction (Lanthanide contraction)
The effect of the full 4f (4f14) orbitals on the lanthanide elements, as well as post-lanthanide transition elements (5d elements) and main group elements Tl, Pb, Bi, Po, resulting in lower than expected radii and increased ionization potentials.
What is the reason for f-block contraction?
poor shielding of the nuclear charge by the f electrons, resulting in a stronger attraction of valence electrons by the nucleus
