The transition elements form three series of metals that progress from elements that give up or lose electrons to elements that gain or accept electrons. The elements that are in transition from metals to non metals are located in the center of the periodic table in periods 4, 5 and 6 and are found in groups 3 through 12.
The transition elements or transition metals are elements whose atom has an incomplete d sub shell or which can give rise to cations with an incomplete d sub shell. Transition elements may be defined as the element whose atoms or simple ions contain partially filled d-orbitals.
Transition Metals DefinitionBack to Top
"The transition metals are defined as those elements which have partly filled d or f shells either in the elemental state or their compounds. The transition metals react with a Variety of groups or molecules called ligands (L) to yield transition metal complexes."
The first transition series involves the filling of 3d orbitals, second 4d orbitals, third 5d orbitals. The general electronic configuration of transition elements is (n-1)d1-10ns1-2. The transition metals are also unique in their outermost valence shell is not the main energy level being completed by sharing electrons. The transition metals are unique in representing a gradual shift in electronegativity. Electronegativity is characterized by the neutral atom ability to acquire electrons from outside itself and thus neutral atoms have a tendency to become negatively charged.
Transition Metals on the Periodic TableBack to Top
- Most of the elements in this family are hard, strong and shiny metals.
- Most of them have very high melting points and boiling points.
- Mercury is one exception it is a liquid at room temperature.
- Most transition elements are good conductors of heat and electricity.
- Most transition elements will dissolve in acid. Gold is one exception it resists acids.
The transition metals change gradually as one moves from left to right across the bridge. On the left side of the bridge the elements have only a few electrons moving through their valence shell.
Transition Metals ListBack to Top
||Period 4 after [Ar]||Period 5 after [Kr]||Period 6 after [Xe]||Period 7 after [Rn]|
||Lutetium||71||6s2 4f14 5d1||Lawrencium||103
||7s2 4f14 7p1
|4||Titanium||22||4s2 3d2||Zirconium||40||5s2 4d2||Hafnium||72||6s2 4f14 5d2||Rutherfordium||104||7s2 4f14 6d2|
|5||Vanadium||23||4s2 3d3||Niobium||41||5s1 4d4||Tantalum||73||6s2 4f14 5d3||Dubnium||105||(unknown)|
|6||Chromium||24||4s1 3d5||Molybdenum||42||5s1 4d5||Tungsten||74
||6s2 4f14 5d4||Seaborgium||106||(unknown)|
|7||Manganese||25||4s2 3d5||Technetium||43||5s2 4d5||Rhenium||75||6s2 4f14 5d5||Bohrium||107||(unknown)|
|8||Iron||26||4s2 3d6||Ruthenium||44||5s1 4d7||Osmium||76||6s2 4f14 5d6||Hassium||108||(unknown)|
|9||Cobalt||27||4s2 3d7||Rhodium||45||5s1 4d8||Iridium||77||6s2 4f14 5d7||Meitnerium||109||(unknown)|
||6s1 4f14 5d9||Darmstadtium||110||(unknown)|
||Copper||29||4s1 3d10||Silver||47||5s14d10||Gold||79||6s1 4f14 5d10||Roentgenium||111||(unknown)|
|12||Zinc||30||4s2 3d10||Cadmium||48||5s2 4d10||Mercury||80||6s2 4f14 5d10||Copernicium||112||(unknown)|
Post Transition MetalsBack to Top
"The transition metals in the last row are not found in nature but have been synthesized artificially. The metals that follow the transition metals are called post transition metals."
Metallic elements from periods 4-6 in groups following the transition series are post transition metals. They are less electropositive than the pre transition metals and are typically found in nature as sulfides rather than silicates. They form compounds with oxidation states corresponding to d10 ions where s and p electrons have been ionized but these are less ionic in character than corresponding compounds of pre transition metals. In solution post transition metals form the stronger complexes than with pre transition metals.
Transition Metal ChargesBack to Top
- Transition metals form cations but can lose varying numbers of electrons thus forming ions of different charges.
- Therefore the group number is not an accurate guide to charges. It is important to learn which ions are forms most frequently by these metals.
- Many transition metals form +2 and +3 ions. For example, iron atoms can lose two or three electrons to form Fe2+ or Fe3+ respectively.
Transition Metal ComplexesBack to Top
The characteristic color of many transition metal complexes MLn arise either from d-d* transitions at a metal center or from charge transfer transitions between a metal center M and the ligands L.
Some examples of complexes where the color arises from d-d* transition are [Cr(H2O)6]3+ (violet) and [Co(NH3)6]3+ (gold brown). There are two types of charge transfer process. In the first case the electron is transferred from the ligand to the metal, the transfer produces metal reduction bands in the UV spectrum. The second type of CT processes is electron migration from metal to ligand which leads to metal oxidation bands in the UV region.
Electron Configuration of Transition MetalsBack to Top
|Group number||4||5||6||7||8 ||9|| 10||11
||Ti||V ||Cr ||Mn ||Fe||Co ||Ni ||Cu
||Zr ||Nb ||Mo ||Tc ||Ru ||Rh ||Pd ||Ag|
||Hf ||Ta ||W||Re||Os ||Ir ||Pt ||Au
|Oxidation states||0||4||5 ||6 ||7 ||8 ||9 ||10 ||--
||3 ||4 ||5 ||6 ||7 ||8 ||9 ||10
||2||3 ||4 ||5 ||6 ||7 ||8 ||9
||1 ||2 ||3 ||4 ||5 ||6 ||7 ||8
|IV||0 ||1 ||2 ||3 ||4 ||5 ||6 ||7
Oxidation States of Transition MetalsBack to Top
It may be noted the oxidation states of transition elements differ from each other by unity whereas oxidation states of non transition elements generally differs by two. The highest oxidation state shown by any transition metal is +8 and the lower oxidation state is generally +2 and +3. Some transition metals also show oxidation state of zero in their compounds.
Characteristics of Transition MetalsBack to Top
- Transition elements are metals.
- They exhibit variable valency or oxidation state.
- They are less reactive than s-block and p-block elements.
- They generally form colored compounds except those compounds in which the metal ion have either d0 or d10 electrons.
- Transition metals and their compounds have marked catalytic activity.
- They form complex compounds.
- They are generally paramagnetic that is attract magnetic lines of forces. This property is due to presence of unpaired electrons in d-sub shell. On account of absence of unpaired electron they are diamagnetic.
Uses of Transition MetalsBack to Top
||Examples of uses
||Alloys with aluminum|
||Space and aircraft vehicles, replacement hi joints.
||Alloys with iron to make hard steels.
||Alloys with iron to make stainless steel for cutter.
|5||Manganese ||Alloys with iron for making springs, paper clips.|
|6 ||Iron||Making steels for cars, machines, construction girders.|
|7 ||Cobalt||Alloys with iron to make hard steel.|
|8 ||Nickel||Alloys with copper to make coinage metals.|
|9 ||Copper ||Electrical and plumbing work making the alloys brass and bronze coins. |
|10 ||Zinc||Coating for iron (galvanizing) alloys with copper to make brass.|
Properties of Transition MetalsBack to Top
- They are all metals and have high melting points and boiling points. Car engines for example, are made from iron because it can withstand temperatures over 1000oC without melting.
- They are good conductors of heat and electricity. The wiring in houses and the central heating pipes are made of copper because it is a good conductor of electricity and heat.
- They are strong so are used to build bridges the frames of buildings vehicles and machines.
- Most have a high density. Titanium has a lower density than most transition metals, so it is used to make modern aircraft because it is also strong and can withstand high temperatures.
- They form colored compounds. The compounds of most of the other elements in the periodic table are white