Why do transition metals not have Lewis dot structures?
They do! Bonding with transition metals can definitely be drawn using Lewis dot structures. They are generally not taught until you reach high level chemistry courses however because they do not follow the 8-electron or octet rule as most other elements as taught in high school. Transition metals have valence bonding electrons in 3 different orbitals: s, p, and d (as opposed to say, carbon, oxygen, nitrogen, etc. that only have s and p valence orbitals). Because of the additional d-orbitals in transition metals, which can hold up to 10 electrons, transition metals follow what is known as the 18-electron rule (2 from the s-orbital plus 6 from the p-orbitals plus 10 from the d-orbitals. This 18-electron counting rule works the same as the octet rule, except now you need to use both your fingers and toes! ;-)
Rather hard to represent 3-d depictions of molecular structures on a 2-d surface short of folding the paper. That's around all otherwise it is a simple and common way to depict chemical structures Lewis dot Structures and Covalent bonds are completely different. The Lewis dot takes or gives, while covalent bonds share.
Lewis structures (also known as Lewis dot diagrams, electron dot diagrams, and electron dot structures) are diagrams that show the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule. A Lewis structure can be drawn for any covalently - bonded molecule, as well as coordination compounds. The Lewis structure was named after Gilbert Newton Lewis, who introduced it in his 1916 article The Atom and the…
How do the electron-dot structures of elements in the same group in the periodic table compare to one another?
The number of valence electrons in the transition metals is somewhat different than main group elements. As you go from left to right across the periodic table, the electrons added to the transition metals go into the d-orbitals. However, because the energy of the 4s orbital is lower than the 3d orbital (and the 5s is lower than the 4d, etc.), the 4s orbital fills first. Therefore the electron configuration of iron for instance is…
Since the actual shapes of structure of molecules is 3-dimensional and is not easy to represent on paper, Lewis gave the idea of drawing structures of elements with their symbols surrounded by valence electrons. These valence electrons are represented by dots and hence this concept came to be known as Lewis dot structure theory.