A Guide to the Inner Transition Elements

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There are 118 known elements on the periodic table, but they aren’t just arranged by atomic weight and number. Instead, the periodic table can be subdivided into different groups based on various elemental properties. Some of these groups, like the noble gases, are relatively small and straightforward. Other groups, like the inner transition elements, which we’ll be exploring today, are a bit more complex. But these elements have important properties and many scientific and industrial uses, so it’s valuable to know them!

What Are Inner Transition Elements?

Inner transition elements, also known as the inner transition metals, are a set of chemical elements found in the periodic table's f-block. This set of elements can be categorized into two two series: the lanthanides and the actinides. These elements are characterized by the filling of the 4f and 5f electron orbitals. They possess complex electron configurations and exhibit unique properties, such as magnetism, luminescence, variable oxidation states, and even radioactivity!

Why Are They Called Transition Elements?

These elements are called transition elements because they exhibit transitional properties between the s-block and d-block elements. Specifically, inner transition elements involve the gradual filling of inner f-orbitals, leading to a transition in chemical and physical properties within the series. This inner electron filling differentiates them from the outer transition metals, which fill the d-orbitals. The term "transition" reflects their role in bridging the gaps in the periodic trends of element properties. Inner transition elements play significant roles in various technological and scientific applications due to their unique chemical characteristics, making them essential components in modern industry and research.

The Lanthanides

The lanthanides are a series of 15 elements ranging from atomic numbers 57 (Lanthanum) to 71 (Lutetium). Named after the first element in the series, lanthanum, these elements are often referred to as rare earth metals. They are silvery-white, soft metals that tarnish easily when exposed to air. Lanthanides are known for their magnetic and phosphorescent properties, which make them valuable in various modern technologies; you’ll find them in everything from electric motors and wind turbines to headphones and LED screens.

The lanthanide elements are:

The Actinides

The actinides consist of 15 elements with atomic numbers from 89 (Actinium) to 103 (Lawrencium). Named after actinium, the first element in the series, actinides are unique because most of them are radioactive. This means they emit radiation as they decay into other elements, which can make exposure to them dangerous. Actinides like uranium and plutonium are well-known for their use as fuel in nuclear reactors and in nuclear weapons due to their ability to undergo fission. Other actinides are used in medicine for radiation therapy and in scientific research.

The actinide elements are:

Where Are the Transition Elements Found on the Periodic Table?

Inner transition elements are located in the two rows at the bottom of the periodic table, separated from the main body to maintain its structure and readability. The first row is the lanthanide series– Lanthanum to Lutetium– and the second row is the actinides, spanning Actinium to Lawrencium. Their position reflects their unique electron configurations and the challenges in fitting them into the standard periodic table layout.

How Are Inner Transition Elements Used?

Here's what you need to know about the inner transition elements.

Inner transition elements have a wide range of applications in modern technology, medicine, and industry. Their unique electronic structures allow them to participate in complex chemical reactions and exhibit special properties like magnetism, luminescence, and radioactivity. These characteristics make them valuable in fields such as electronics, renewable energy, nuclear power, and medical diagnostics. From powering spacecraft to improving medical imaging, inner transition elements contribute significantly to technological advancements.

Common Uses of Inner Transition Elements

Lanthanides		Actinides
Element	Uses	Element	Uses
Lanthanum	Camera and telescope lenses, petroleum refining, nickel-metal hydride batteries for hybrid vehicles	Actinium	Cancer treatment, neutron sources, research in radioactivity
Cerium	Catalytic converters, glass polishing powders, ignition flints	Thorium	Alternative nuclear fuel, high-end optics, gas mantles
Praseodymium	High-strength metals for aircraft engines, coloring agents in glass and ceramics, strong permanent magnets	Protactinium	Scientific research, radiometric dating, study of heavy elements
Neodymium	Powerful magnets, lasers, headphones and loudspeakers	Uranium	Nuclear fuel, military applications, ceramic coloring
Promethium	Nuclear batteries for satellites, luminous paints, materials science gauges	Neptunium	Neutron detectors, plutonium production, nuclear waste studies
Samarium	Samarium-cobalt magnets, neutron absorbers in reactors, infrared-absorbing glass	Plutonium	Nuclear reactors, space missions, nuclear weapons
Europium	Red phosphors in screens, anti-counterfeiting in banknotes, control rods in nuclear reactors	Americium	Smoke detectors, industrial gauges, neutron sources
Gadolinium	MRI contrast agents, computer memory chips, shielding in nuclear reactors	Curium	Space power sources, analytical instruments, research
Terbium	Green phosphors in displays, solid-state devices, fuel cell stabilizers	Berkelium	Synthesis of new elements, study of actinides, nuclear research
Dysprosium	High-performance magnets, laser materials, control rods in nuclear reactors	Californium	Neutron emitters in mining, medical treatments, material analysis
Holmium	Medical lasers, magnetic flux concentrators, coloring glass and gemstones	Einsteinium	Research purposes, synthesis of heavier elements, nuclear studies
Erbium	Optical fiber amplifiers, dermatological lasers, pink coloring in glass	Fermium	Nuclear research, study of transuranic elements, neutron capture experiments
Thulium	Portable X-ray sources, medical lasers, superconductors	Mendelevium	Research in chemistry of heavy elements, nuclear structure studies, electron configuration research
Ytterbium	Steel refinement, fiber optics, atomic clocks	Nobelium	Atomic theory research, study of chemical bonding, relativistic chemistry
Lutetium	Catalysts in cracking processes, PET scan detectors, specialized glass	Lawrencium	Research on electron orbitals, properties of actinides, nuclear research

Discover The Inner Transition Elements

Inner transition metals are good to know.

To learn more about the inner transition elements and other elements on the periodic table, explore Engineered Labs’ collection of acrylic element cubes and hands-on periodic tables. Our catalog is full of unique elemental displays perfect for chemistry classrooms and enthusiasts! Connect with these elements safely from the comfort of your home or school.

Written by Chandler Johnson