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Chemistry periodic table

Middle School Chemistry

Transition Metals

Metals vs Non-Metals

Look around you. Metal objects are everywhere. Metal utensils on the table, metal wires that carry electricity to your house and even the metal coins in your pocket. Metal structures that support large buildings are also present. All of the mentioned objects use metals that belong to the transition metals group. Metals are also present in your body and perform several important functions.

But do metals behave the same way? Consider the following questions:

  • Why does iron rust, but gold remains shiny and untarnished?
  • Why are some metallic compounds blue, green, or yellow and not just dull grey?

In chemistry, when studying metals, they are not just categorized as "hard and shiny". Their behavior, reactivity and roles in chemical reactions differ. Transition metals are of great importance due to their exceptional properties. They are used in industries, technologies and even in biological systems.

At the end of this lesson, you will be able to:
  • Define 'Transition Metals'
  • Locate them on the periodic table
  • Describe the unique characteristics of transition metals
  • Explain their significance in real life

What Are Transition Metals?

These metals can be found at the center of the periodic table in its middle block. A few are:

  • Iron (Fe)
  • Copper (Cu)
  • Zinc (Zn)
  • Nickel (Ni)
  • Cobalt (Co)
  • Chromium (Cr)
  • Silver (Ag)
  • Gold (Au)

Why Are They Called "Transition Metals"?

These are called "transition metals" because they are the metals closest to the metals and non-metals on the periodic table. They are also in the middle of the table and are in between all the very reactive metals on the left and the non-metals on the right. They combine the different characteristics of these two groups.

Most simply put, transition metals are a series of metals that exhibit unique chemical and physical properties in comparison to the other metals, such as sodium or calcium.

Key characteristics of transition metals:

  • They are hard and very strong
  • They are excellent conductors of heat and electricity
  • They are capable of forming a great number of colorful compounds
  • They are highly used as constituents of tools, machines, vehicles, and electronic devices

Position in the Periodic Table

Periodic Table with Transition Metals Highlighted

Transition metals are positioned inside the d-block of the periodic table. This section is right in the middle of the table and is positioned between the alkaline/alkaline earth metals on the left and the non-metals/metalloids on the right.

Physical Properties of Transition Metals

Physical properties of transition metals

Transition metals have a multitude of similarities that make them beneficial materials for use in everyday life and in industry.

  • Hard and strong – This is why iron is used to construct bridges, buildings, and tools.
  • High boiling and melting points – This means they do not melt easily, which makes them ideal for high-temperature purposes such as in engines and furnaces.
  • Good conductors of heat and electricity – This is why copper wires are used in electrical circuits; copper is a metal that permits the flow of electric current easily.
  • Shiny when freshly cut – This shiny appearance is known as metallic luster and it is the reason metals are utilized for ornamentation and jewelry.
  • Malleable and ductile – Malleable means they can be hammered to form thin sheets, and ductile means they can be stretched to form wires.

Chemical Properties of Transition Metals

Unlike sodium or potassium that explode violently, transition metals are less reactive, and they still participate in a wide range of chemical reactions.

Formation of Compounds

They can form compounds with non-metals like sulfur, chlorine, and oxygen. Iron, for instance, combines with oxygen and produces the compound iron oxide, which we commonly refer to as rust.

Formation of Ions

They can form a variety of different ions. This capability enables them to have chemistry that is rich and varied.

Catalytic Role

They often take on a catalytic role in chemical reactions. This means they can accelerate a chemical reaction without being consumed in the process.

Colored Compounds

They form compounds that have color — one of the more fascinating characteristics of transition metals.

Variable Oxidation States

Transition metals exhibit the trait of possessing several oxidation states, defined as the charge of an ion within a compound.

  • Iron can exist as Fe²⁺ and Fe³⁺
  • Copper can exist as Cu⁺ and Cu²⁺
Importance of Variable Oxidation States:
  • Enables a chemical species to form a variety of different compounds
  • Generates the ability to take part in redox (reduction and oxidation) processes, which involve the transfer of electrons
  • Makes metals of great use in industries

Colored Compounds

A good number of compounds of transition metals are colorfully attractive.

  • Compounds of copper are blue or green
  • Compounds of iron are yellow, brown, or green

Why are these colors?

Metal ions have electrons that absorb certain wavelengths of light. The light that is not absorbed is what gives the substance its color.

What do we use these colored compounds for?

  • Pigments and dyes
  • Indicators for laboratories
  • Finding metals

Catalytic Properties

A lot of the time, the transition metals are catalysts. A catalyst is a substance that increases the rate of a chemical reaction and isn't consumed in the reaction.

Catalyst Reaction
Iron Production of ammonia
Platinum Combustion in the car

Why are they able to do that?

  • They are able to gain or lose electrons relatively easily
  • They provide a surface for the reaction
  • They provide an alternative reaction pathway that requires less energy

Formation of Complex Ions

The transition metals are also able to form what are known as complex ions. A complex ion consists of a metal ion and a number of molecules or ions, known as ligands. These formations are special and have unique traits.

Significance:

  • Describes the different colors of various solutions of metals
  • Describes how a metal behaves when it is placed in water
  • Key to potential mechanisms of proteins and enzymes

Use in Everyday Life

Everywhere you go, there are transition metals:

  • Construction – iron and steel for making buildings and bridges
  • Electrical uses – copper wires
  • Transportation – strong, corrosion-resistant alloys
  • Medicine – various instruments and treatments
  • Coins and jewelry – silver and gold

Alloys

An alloy is a combination of two or more elements of which at least one is a metal. Transition metals give better and stronger alloys. For example, steel is made of iron and a few other metals.

  • Stronger for construction
  • Lighter for use in vehicles
  • Resistant to corrosion for use outdoors

Importance in Biological Systems

Some of the transition metals are important for our survival:

  • Iron is a part of hemoglobin and is responsible for the transport of oxygen
  • Zinc helps in the functioning of enzymes as well as in the functioning of the immune system
  • Copper is important in the production of energy in the body as well as in the formation of connective tissues

Life processes cannot occur in the absence of these elements, although the required quantity is very small.

Corrosion and Protection

Metals can react with air and water, which can lead to corrosion. A common example is iron rusting. Corrosion is a process that weakens metals.

Ways to protect metals from corrosion:

  • Coating with paint
  • Covering with another metal
  • Using alloys that resist corrosion

Why Are Transition Metals Important?

Transition metals share several important characteristics that make them central to both chemistry and industry:

  • Form colored compounds
  • Have several different oxidation states
  • Are useful in catalysis
  • Can form complex ions

This allows us to understand how to:

  • Study how electrons in materials behave
  • Design materials with desired properties
  • Relate chemistry to daily activities