why the transition metals have high melting point, have high density, and forming coloured?

Question

why they're called as a collection of metal?

Answer 1

Transition metals have high melting points because they are metals! All metals have high melting points! But some transition metals have exceptionally high melting points like Vanadium and Nickiel because they form a partially half filled 3-d subshell (for Vanadium) and a fully filled 3-d orbital (for Nickiel), which adds to an extra stability to the element. Hence, it is more difficult to remove the electron and thus result in the high melting point.


Since transition metals are all in the 4th period, its Ar would be large too. Since Ar is large, naturally density would be high.

Because mass=no. of molecules x Ar

And density is defined as mass / volume.


The specialty of transition mentals is that the energy levels of the orbitals are close enough to overlap each other. When electrons of a transition metal gains energy and is excited, it is promoted to the 4s orbital.


However, it is unstable at that level and soon drops back to the 3d-orbital. In order to return to the 3d-orbital, it must remove some of its energy, and the energy is light. That is why there are different colours in transition metals. Because it only releases a specific amount of energy, which relects different colours of light. This process is also known as d-d transition.

Answer 2

Removing an electron has nothing to do w/ melting point.

The transition metals do have many unpaired electrons...in d-orbitals as folks have pointed out.

These electrons on one atom can be shared w/ those from another atom...forming chemical bonds. Since there are many unpaired electrons, they can form many bonds.

Chemical bonds form and release energy, thus it takes energy to break a bond. Melting is the breaking of these bonds (thus the atoms can flow, as opposed to being held in place in a lattice).

If you have lots of bonds (which we established transition metals do) then it will take lots of energy to break those and melt.

High density comes b/c transition metal atoms are pretty massive (remember they start w/ Sc, atomic wt: 44, which is much heavier than the common elements of H, O and Si) yet these chemical bonds cause the atoms to be packed together tightly. Density=mass/volume, and we said mass is high, volume fairly low, thus density will be large.

Coloured...as a spectroscopist, this is my favorite! The electons in the d-orbitals can be excited to other, higher energy levels. This can be done by absorbing electro-magnetic radiation...light! Transition metals have many d-orbitals (and f-orbitals) that are are at energy levels just right to absorb some visible light (as opposed to ultra-violet light). Thus it may be red light absorbed, leaving blue/green light to pass through, and you see a solution having the blue/green color. Lots of combinations exist, meaning lots of colors can be formed w/ these metals.

Trying to keep it brief, hope this gives you a good start.

Answer 3

This Site Might Help You.

RE:
why the transition metals have high melting point, have high density, and forming coloured?
why they're called as a collection of metal?

Answer 4

Melting Point Of Vanadium

Answer 5

Vanadium Melting Point

Answer 6

highmelting point and high density --they have high heats of atomisation
form coloured compounds because most of them have unpaire electrons which can xcite to highrlevels and when come back releases energy that lie in visible spectrum

Answer 7

Wikipedia has a simple explanation under Characteristic Properties. Or you could do your own homework.

Answer 8

Because of strong bond