What is the trend of melting and boiling points in transition elements
August , 9 Years ago
Grade 12th pass
Physical Chemistry> What is the trend of melting and boiling ...
1 Answers
Umakant biswal
Last Activity: 9 Years ago
Transition metals have high melting points due to strong metallic bonds. Number of unpaired electrons in the outermost shell indicates the strength of the metallic bonds. Therefore, the more unpaired electrons are present, the higher melting point will be. The first 4 elements in a row always have the highest melting points. However, as the unpaired d orbital electrons pair up, the melting point decreases. The last 5 elements in a row have a lower melting point than the first 4 elements. The last element in each row has the lowest melting point because the d orbital electrons are filled.
lets look at an example between Scandium (Sc) and Zinc (Zn).
Sc: [Ar] 4s² 3d¹ lets take a look at the d orbital:
For Sc we see that there is only one electron in the d-orbital and that electron is unpaired.
Melting point of Sc is 1814 K.
Generally, for transition metal groups, halogens, noble gases, and some nonmetals boiling & melting points increase as you move from top to bottom (increase in atomic number).
For alkali metals and groups around the metalloids, both melting points and boiling points decrease with increasing atomic number.
As atomic number increases, the points increases due to there being more electrons, which create a larger strength of negative charge around the nucleus of the atom.
This affects the Van Der Waals' forces (the forces of attraction between molecules or atoms) and they become stronger. With stronger forces, it requires more energy required to change the state of the element - resulting in a higher boiling/melting point ..
hope it clears your doubt..
MELTING AND BOILING POINT VARIES WITH UNPAIR ELECTRON ..
lets look at an example between Scandium (Sc) and Zinc (Zn).
Sc: [Ar] 4s² 3d¹ lets take a look at the d orbital:
For Sc we see that there is only one electron in the d-orbital and that electron is unpaired.
Melting point of Sc is 1814 K.
Generally, for transition metal groups, halogens, noble gases, and some nonmetals boiling & melting points increase as you move from top to bottom (increase in atomic number).
For alkali metals and groups around the metalloids, both melting points and boiling points decrease with increasing atomic number.
As atomic number increases, the points increases due to there being more electrons, which create a larger strength of negative charge around the nucleus of the atom.
This affects the Van Der Waals' forces (the forces of attraction between molecules or atoms) and they become stronger. With stronger forces, it requires more energy required to change the state of the element - resulting in a higher boiling/melting point ..
hope it clears your doubt..
MELTING AND BOILING POINT VARIES WITH UNPAIR ELECTRON ..
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