Chemistry of the f-Block Elements

Helen C. Aspinall

• Publisher: CRC Press
• Year: 2018
• eBook ISBN: 9781351461146
• Edition: 1
• Topic: Ciencias físicas
• Subtopic: Química

Visual Spatial Enquiry explores visual and textual ways of working within spatial research. Architects and spatial thinkers from the arts, social sciences and humanities present rich case studies from remote and regional settings in Australia to the suburbs of Los Angeles, and from gallery and university settings to community collaborations in Mongolia. Through these case studies the authors reappraise and reconsider research approaches, methods and processes within and across their fields. In spatial research diagramming can be used as a method to synthesise complex concepts into a succinct picture, whereas metaphors can add the richness of lived experiences. Drawing on the editors' own architectural backgrounds, this volume is organised into three key themes: seeing, doing and making space. In seeing space chapters consider observational research enquiries where developing empathy for the context and topic is as important as gathering concrete data. Doing space explores generative opportunities that inform new and innovative propositions, and making space looks at ways to rethink and reshape spatial and relational settings. Through this volume Creagh and McGann invite readers to find their own understandings of the value and practices of neighbouring fields including planning, geography, ethnography, architecture and art. This exploration will be of value to researchers looking to develop their cross-disciplinary literacy, and to design practitioners looking to enhance and articulate their research skills.

Chapter 1

INTRODUCTION

The lanthanide elements are usually defined as those in which the 4f-orbitals are progressively filled; this definition includes the elements Ce (cerium) to Lu (lutetium). Although not a lanthanide by this definition, La (lanthanum) is the prototype for the series and for practical purposes is usually included. The term ‘rare earth’ dates back to the early 19th century and is applied to elements 57 to 71 (La to Lu) and also to Y (yttrium), which is found in nature along with the lanthanides. Sc (scandium) is often also classed as a rare earth. The elements Th (thorium) to Lr (lawrencium) form the actinide series which is formally a 5f analogue of the lanthanide series, with Ac (actinium) as its prototype. This ‘actinide concept’, proposed in 1944 by Glenn Seaborg, solved the problem of where to fit the trans-uranium elements into the periodic table. The chemistry of the early actinides is quite distinct from that of their 4f congeners, and prior to 1944 the elements Th to U had been placed in the periodic table immediately below Hf, Ta and W. The late actinides show many similarities to the lanthanides.

Figure 1.1 The rare earth and actinide elements in the periodic table.

1.1 HISTORY

1.1.1 Lanthanides

The story of the lanthanides begins in 1787 when a young Swedish artillery officer, Lieutenant Carl Axel Arrhenius, who was a keen amateur geologist, was exploring a quarry at a small town called Ytterby, near Stockholm. He found a new, very dense black mineral which he named ytterbite’. At the time there was some speculation that the mineral might contain the recently discovered element tungsten, but the first serious chemical analysis was carried out in 1794 by Johan Gadolin, a Finnish chemist. Methods of chemical analysis were limited in the 18th century, but after a series of treatments with acids and alkalis, Gadolin was able to show that the new mineral contained oxides of iron, beryllium, and silicon and a new, previously unidentified ‘earth’ which he named ‘yttria’. (At the time, the term ‘earth’ was applied rather loosely to insoluble metal oxides.) Yttria was later shown to be a mixture of the oxides of six rare earth elements. A great deal of painstaking work was to follow during the 19th century: the first pure sample of dysprosium was obtained after 58 recrystallisations, and the first sample of Tm took 11000 crystallisations! With the discovery of lutetium (Lu) in 1907, the naturally occurring rare earths had all been isolated. Mosely’s pioneering work on X-ray spectroscopy in the early 20th century was invaluable in determining the purity (or otherwise) of newly discovered elements and also in pointing out the gaps in the Periodic Table. The missing element number 61, promethium, was synthesised and characterised in 1947, completing the lanthanide series. For an account of the history of promethium see Cotton (1999). Some of the history of the lanthanides is summarized in Table 1.1.

1.1.2 Actinides

Uranium was the first of the f-block elements to be discovered: its history dates back to 1789, the year of the French Revolution. Its story begins in Sankt Joachimstal in Bohemia, where silver had been mined since the 16th century. By the first half of the 17th century, silver mining had almost ceased, but bismuth and cobalt deposits were still being exploited, and a new shiny black mineral had been detected. This mineral was nicknamed ‘pitchblende’ from the German pech meaning ‘bad luck’ and blende meaning ‘mineral’. Pitchblende was first subjected to a chemical analysis by the German chemist Martin Klaproth who isolated what he called ‘a strange kind of half metal’ from the mineral. He named the new element ‘uranium’ after the recently discovered planet Uranus. Over the next century or so uranium deposits were found throughout the world: Cornwall in England, Morvan in France and in Austria and Romania. Uranium oxides and salts were widely used as pigments for ceramics and glass, and uranyl nitrate was also used to give a sepia tint to photographs. In the early part of the 20th century, the discovery of radium in pitchblende, and its medical applications, led to a further interest in seeking out deposits of this mineral. The largest use of uranium is now in nuclear power.

Thorium, the only other act...

Table of contents

• Cover Page
• Half Title
• Volume
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Chapter 1 Introduction
• Chapter 2 Spectroscopy
• Chapter 3 Coordination Chemistry
• Chapter 4 Organometallic Chemistry
• Chapter 5 Lanthanide Complexes as Catalysts and Reagents for Organic Reactions
• Index