Some metals are in a special group. 
Some metals belong to a special group. 

Group 7 is a family of metals in the periodic table. 
Each metal is different in nature. Manganese is quite common in the world. Rhenium is very rare. Technetium is also hard to find in small amounts. Bohrium is different because it is synthetic. This means people make it in a lab.
These metals often look silvery or gray. They can also look like shiny metal. 
Some metals in this group form special shapes. Technetium can form many kinds of shapes. 
Group 7 is a special family of metals in the periodic table. 
These metals work in different ways when they react with other things. Many of them like to reach a state called an oxidation state of +7. This is a way of describing how they share electrons. As you move down the group, this +7 state becomes more stable. For example, manganese can form many different oxides. One type, manganese(IV) oxide, is a black or brown solid. It is found in nature as a mineral called pyrolusite. 
History shows us how we discovered these metals. Manganese is a common element found in nature. Technetium was first studied in a different way in 1949. Scientists produced technetium(IV) oxide by using a process called electrolysis. This involves using electricity to change a liquid solution. Rhenium is much rarer than manganese. 
There are many interesting facts about their physical properties. Manganese is a silvery metal with a melting point of 1246 °C. Technetium is a silvery-gray metal that melts at 2157 °C. Rhenium is also silvery-gray and has a much higher melting point of 3186 °C. 
You can see these metals working in things you use every day. Manganese(IV) oxide is a key part of dry-cell batteries. 
Group 7 is a specific family of elements located in the d-block of the periodic table. 
The chemical behavior of Group 7 is largely defined by their oxidation states. An oxidation state describes the charge an atom takes on when it forms compounds. Most members of this group readily reach a +7 oxidation state. This trend becomes more stable as you move down the group from manganese to bohrium. However, the group is less consistent in this pattern than the groups preceding it. For example, technetium can maintain a stable +4 state. Rhenium also shows stability in both +4 and +3 states. Bohrium is expected to exhibit these lower states as well. In high oxidation states, these metals often form oxyanions, which are ions containing oxygen.
Each element in Group 7 has a different origin and abundance in our world. Manganese is a fairly common element found in nature. In contrast, rhenium is considered a rare element. Technetium is even more elusive, occurring only in trace quantities in nature. Bohrium is entirely different because it is a synthetic element. This means it does not occur naturally and must be created by scientists in a laboratory. The physical structures of these elements also vary. Most of the group crystallizes in a hexagonal close packed (hcp) structure. Manganese is the exception, as it uses a body centered cubic (bcc) structure. Bohrium is predicted to follow the hcp pattern used by its neighbors.
The physical properties of these metals change significantly as you move down the periodic table. Manganese is a silvery metal with a melting point of 1519 K (1246 °C). As you move to technetium, the melting point rises to 2430 K (2157 °C). Rhenium has an even higher melting point of 3459 K (3186 °C). The density of these elements also increases dramatically. Manganese has a density of 7.21 g/cm³, while rhenium reaches 21.02 g/cm³. 
Manganese is known for forming a wide variety of oxides. Manganese(II) oxide creates green crystals and can be nonstoichiometric, meaning its composition varies slightly. 
Technetium and rhenium also form important compounds with oxygen and halogens. Technetium(IV) oxide was first produced in 1949 through electrolysis. 

These elements have practical uses in modern technology and science. Manganese(IV) oxide is a critical component in dry-cell batteries, such as alkaline and zinc-carbon batteries. 
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