Chemistry

Examples of Transition Metals

We explain that what are examples of transition metals? The transition metals are the metallic elements that are located at the center of the periodic table, and are distinguished by their usefulness for human activities. They are characterized by having a tightly packed structure , where the atoms have a relatively small radius.

Due to the above property, these elements form strong metallic bonds and, consequently, their densities, melting and boiling points, heats of fusion and vaporization are higher than in the metals of groups IA, IIA and IIB. The electron configurations of the transition, from scandium (Sc) to copper (Cu), group their last electrons in the 3d orbitals.

Transition Metal Properties

Transition metals have a number of physical and chemical characteristics that differentiate them from other elements.

Its natural form
High density
Malleability
Ductility
Oxidation states
Some react with acids
Combine with anions
Thermal conductivity
Electric conductivity
They form coordination compounds

Its natural form

Transition metals are generally found in mineral deposits, forming part of stable chemical compounds such as oxides, binary salts or oxysalts. For example, iron (Fe) is usually found as sulfide (FeS), and is called “pyrite”; titanium (Ti) is found as a mineral called “rutile”, made up of its oxide (TiO ₂ ).

Iron is the most abundant transition metal in the earth’s crust, comprising 6.2% by mass, after the metal aluminum. Other ways in which it can be found are the ores (stones concentrated in a substance) of its oxides, such as hematite (Fe ₂ O ₃ ), siderite (FeCO ₃ ) and magnetite (Fe ₃ O ₄ ). Pure iron is a gray metal and is not particularly hard.

High density

Density is the amount of matter in each unit of volume. It is generally measured in grams for each cubic centimeter (g / cm ³ ) or grams for each milliliter (g / mL), which is the same. Transition metals, because they have a very compact internal structure, generate a large mass per unit volume; they are consequently very dense.

The osmium (Os) is one of the metals with higher density . Its value is 22.61 g / cm ³ . It is followed by iridium (Ir) , with a density of 22.56 g / cm ³ . Platinum (Pt) has a density of 21.45 g / cm ³ , and that of rhenium (Re) has a value of 21.02 g / cm ³ . Density has a lot to do with melting point. Generally, the more compact the atoms are, the more heat is involved in melting the element.

Malleability

The malleability is the property of the materials that allows them to receive efforts to become sheets and geometric figures that fulfill a function or need. Malleable metals are gold (Au), silver (Ag), copper (Cu), chromium (Cr), for example. Thanks to this property, coins or sheets can be created.

Ductility

Ductility is the property of materials that allows them to receive compression forces to become thin wires that fulfill a function or need. Generally, this function is to conduct electric current , and copper (Cu) is the pioneer metal for this. Although gold and silver are still better conductors, copper is good and cheaper.

Oxidation states

Transition metals have various oxidation states in their compounds, the most common of which are +2 and +3. The +2 oxidation state tends to be more stable at the end of the series, especially in Nickel and Copper. In contrast, the +3 was more stable at the beginning, in the elements Scandium, Titanium, Vanadium.

The oxidation state or maximum valence for a transition metal is +7 , which is the case for manganese, whose electronic configuration ends in (4s ² , 3d ⁵ ). Transition metals almost always present their maximum valences in compounds with highly electronegative elements, such as oxygen and fluorine, for example, in compounds V ₂ O ₅ , CrO ₃ , Mn ₂ O ₇ .

Some react with acids

Although the transition metals are more electronegative than the alkali and alkaline earth metals, their potential reduction standards indicate that, except for copper, they should all react with strong acids (such as hydrochloric acid HCl) to form hydrogen gas.

However, almost all these metals are inert to acids or react slowly with them, due to the oxide layer that protects them. Like chrome. Although its standard reduction potential is negative, it is almost inert by the oxide Cr ₂ O ₃ , which forms on the surface; hence many metals are commonly plated with chromium to protect them from corrosion.

Combine with anions

Transition metals are naturally found in combination with anions (negative ions) such as nonmetals or radicals, in underground deposits or in mountain systems. It is rare that they are found in their pure state. Some of the most common anions that metals bind with are:

Chloride (Cl ^– )
Bromide (Br ^– )
Sulfur (S ^-2 )
Oxygen (O ^-2 )
Chlorate (ClO ₃^– )
Silicate (SiO ₄^-4 )

Thermal conductivity

Thermal conductivity is the ability of materials to transport heat energy through their internal structure. Transition metals are the best thermal conductors. They include copper, gold and silver . For economy, copper is used as the thermal conductor par excellence, to make electric stoves.

Electric conductivity

Electrical conductivity is the property of materials to transport electrical energy through their internal structure. Transition metals are the best electrical conductors. Copper, gold and silver stand out. For the same reason, the economic one, copper is used for electrical installations in a city .

They form coordination compounds

Transition metals have a particular tendency to form complex ions. A coordination compound usually consists of a complex ion and a counterion. There are exceptions. For example, some coordination compounds, such as Fe (CO) _5, do not contain complex ions.

Chemists in the 19th century were puzzled by certain types of reactions that seemed to contravene the theory of valence. For example, the valences of the elements in cobalt (III) chloride and ammonia appeared to be satisfied. However, these two substances react and form a stable compound that has the formula CoCl ₃ * 6NH ₃ .

To explain this behavior, Alfred Werner, the discoverer, postulated that most elements have two types of valence: a primary valence and a secondary valence. The current term for the primary valence corresponds to the oxidation number and the secondary valence corresponds to the coordination number of the element.

According to Werner, cobalt has a primary valence of 3 and a secondary valence of 6 in CoCl ₃ * 6NH ₃ . Currently, the formula [Co (NH ₃ ) ₆ ] Cl _{3 is used} to indicate that the cobalt atom and the ammonia molecules form a complex ion; chloride ions are not part of the complex, but are bound to it by ionic forces.