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iridium

Primary Information
Secondary Information

Definition

Iridium is a chemical element with the symbol Ir and atomic number 77. It is a very hard, dense, silvery-white metal. Iridium is the second heaviest naturally occurring element on Earth, after osmium. It is also one of the rarest elements, with an estimated abundance of about 0.001 parts per million in the Earth's crust.

Iridium is a member of the platinum group of metals. It is chemically inert and resistant to corrosion. Iridium is also a good conductor of heat and electricity.

Iridium is used in a variety of applications, including:

  • Making jewellery and other decorative objects
  • Making high-temperature alloys
  • Making electrical contacts
  • Plating other metals to make them more resistant to corrosion
  • Studying the composition of meteorites
  • Iridium is also used in some medical applications, such as pacemakers and stents.

How can the word be used?

Iridium alloys are very strong and durable.

iridium

Different forms of the word

Noun: iridium (pronounced ih-rid-ee-um).

Adjective: iridium.

Verb: iridize (pronounced ih-rid-uh-zayz).

Etymology

The word "iridium" comes from the Greek word "ἴρις", which means "rainbow". This is a reference to the fact that iridium can sometimes have a rainbow-like sheen.

The Greek word "ἴρις" is also the root of the word "iris", which is the colored part of the eye.

Question

What can iridium be used for?

AQA Science Exam Question and Answer

Question:

Explain the significance of iridium as an element and its role in scientific discoveries. Discuss its connection to the Cretaceous-Paleogene (K-Pg) mass extinction event and the evidence that led to the hypothesis of an asteroid impact.

Answer:

Iridium is a precious metal element with several intriguing properties. Its high density, corrosion resistance, and unique optical qualities have led to its use in various applications, including electronics, catalysis, and jewellery. However, iridium gained prominence in the field of Earth sciences due to its association with a pivotal event in Earth's history.

The Cretaceous-Paleogene (K-Pg) mass extinction, responsible for the demise of the dinosaurs around 66 million years ago, was a turning point in Earth's biodiversity. Scientists discovered a global layer of iridium-enriched clay in the geologic record, indicating an unusual influx of extraterrestrial material. This discovery supported the hypothesis of an asteroid impact was the cause of the mass extinction.

The iridium layer, found in rocks from various parts of the world, provided strong evidence for the impact hypothesis. The element's presence is believed to result from the vaporisation of the impactor upon collision with Earth, distributing iridium-rich debris globally.

The study of iridium's distribution and its connection to the K-Pg boundary revolutionized our understanding of Earth's history and the impact events that have shaped its evolution. This discovery underscores the importance of interdisciplinary scientific investigations and highlights how elements like iridium contribute to unravelling mysteries of the past.