Chemical Forums
Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: jonogt on January 28, 2008, 12:48:48 PM

I'm supposed to explain why Ti has so much higher of a melting point than K. My structural materials textbook talks about how the farther right of the alkali metals you get, the less metallic and the more covalent the bond gets because of more available valence e's to bond. Makes sense. It also says Ti, as well as the other transition metals, are subject to dsp hybridized bonding.
The only info I can seem to find in my book and online about this is that it's a metalliccovalent mixed bond, which again makes sense, but I'm really not seeing what it is. I know that d,s, and p are the types of orbitals, but intermolecular bonds aren't occuring on all 3 of these orbitals, are they? Can someone explain it a little more logically?
thanks
Jon

K and Ti both have d shells available for bonding. K is an alkali metal with an oxidation state of +1. K, otassum will form ionic bonds with the elements in Group 7 (halogenssalt makers).
Ti is a transion metal. Transition form coordination complexes. If you place transition metals in solution you can determine the corresponding oxidation states of the resulting ions. Transition metals have several oxidation states, but nonbonded transition metals only exhibit relatively low oxidation states. Many transition metals share the same oxidation states, and each row follows similar patterns.
Transition metals form coordination complexes....in solution this is often evidenced by highly colored solutions.
See this link: http://en.wikipedia.org/wiki/Titanium
Yes, Ti has what is called dsp hybridization/bonding. And yes all three orbitals participate in the bonding.
K: 1s^{2}, 2s^{2}, 2p^{6} 3s^{2 } 3p^{6} 4s^{2} or [Ar] 4s^{2}
Ti: 1s^{2} 2s^{2} 2p^{6} 3s^{2 } 3p^{6 } 4s^{2} 3d^{2} or [Ar] 4s^{2} 3d^{2}
Ti^{+2}:[Ar]3d^{2}
Ti^{+3}:[Ar]3d^{1}
For Ti we can write Ti: 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{2} 4s^{2}
So for Ti we have 3s^{2} 3p^{6} 3d^{2}
Ti forms d^{2}sp^{3} Hybrids
These particular d^{2}sp^{3} hybrids are combinations of two 3d, the 3s, and three 3p functions.
The 3s : 3 is the energy level, S is the subshell, 1 orbital
The 3p: 3 is the energy, p is the subshell, 3 orbitals px, py, and pz
The 3d: 3 is the energy, d is the subshell, 5 orbitals d_{yz}, d_{xz}, d_{xy}, d_{x}_{2y2}, and d_{z}_{2.}
In general:
S subshell has only 1 orbital.
The p subshell has 3 orbitals.
The d subshell has 5 orbitals.
The f subshell has 7 orbitals.
In Ti there are 2 electrons in the 3d shell.
Hence, the designation d^{2}sp^{3} Hybrids (TiClan octahedral complex)
For octahedral complexes: There are six d^{2}sp^{3} hybrid orbitals. They are arranged in an octahedral layout so that each has four other orbitals at 90° to it and one at 180°.
The following links should help you too:
http://faculty.colostatepueblo.edu/linda.wilkes/111/3c.htm
http://winter.group.shef.ac.uk/orbitron/AOhybrids/d2sp3/index.html
http://www.chem1.com/acad/webtext/chembond/cb09.html
http://en.wikipedia.org/wiki/Titanium(III)_chloride