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Chemistry & Environmental Dictionary

Thermal Conductivity - Transition Metals

Temperature

the thermal state of matter with reference to its ability to transfer heat to other matter. Temperature is distinguished from heat in that heat is the energy that is transferred between matter by radiation, conduction and/or convection. The three most common scales for measuring temperature are centigrade, Fahrenheit and Kelvin.

Thermal Conductivity

see Conduction

Third Ionization Potential

To be defined

Time Weighted Average (TWA)

An exposure limit based on an 8 hour workday and a 40 hour work week.

Transactinides

all elements that follow the Actinides. As with all elements larger than uranium (U), these elements can only be produced in nuclear reactors or particle accelerators. While some of these elements of the transactinides are commonly lumped with metals, not enough information is available for this site to positively conclude whether elements 116 and 118 should be included with the metals or nonmetals. Indeed it may be completely in appropriate to lump these elements with either the metals or nonmetals. Only time will tell what the scientific community will ultimately decide.

Transition Metals

This series include all elements in the sub-series Lanthanides and Actinides of the inner-transition elements and at least part of the sub-series Transactinides, which are the elements following the Actinides series. In general these elements are known for their hardness, high density, high melting point and boiling point and heat conduction although there are exceptions.

These elements all have a d electron as the differentiating electron in their electron configuration. In other words, their outer most electrons are always in the d orbital.

Iron (Fe), for instance, has an electron configuration as follows:
1s2 2s2 2p6 3s2 3p6 4s2 3d6

Note that the 4 S orbital actually filled before 3d. The 3d acts as the outer most orbital and is the one involved in reactions.

These metals frequently have more than one oxidation state. Our sample Iron has two oxidation states +2 and +3. These may be represented as Iron II and Iron III or the ferrous ion (+2) and ferric ion (+3). Ferrous and ferric are Latin terms. The symbols for iron II and iron III are Fe II and Fe III as one might expect.

Many of these elements are electropositive enough to replace hydrogen (H) from acid solutions. They also form complex ions and coordinate covalent compounds (in which one element dominates both electrons).

The ions of transition elements tend to be colored, making them easy detect in quantitative analysis. The copper(Cu) ion, for instance is aquamarine and cobalt (Co) is blue.

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