What is the atomic number for helium? Sun Element: Helium is named from the Greek word for sun,helios.This is because helium was first detected in the sun's corona. It was first observed by Pierre Janssen, an astronomer, in 1868 but not formally discovered on Earth until 1895. ...
What is the mass number of radium? Mass Number: Elements are composed of only one type of atom and are the basic units of matter. Elements can be defined by several properties, one of which is their mass number. Mass number is the sum of the mass of protons and neutrons in an atom....
Radioactivity, in other words is measured by disintegrations per second. The number of disintegrations per second varies in part on a time scale, and in part on the amount of the isotope present. Because the value can change over time, sometimes values are given within a particular time ...
Telluride refers to a chemical compound containing the element tellurium and another element, usually a metal; tellurium is a chemical element itself, symbolized as Te and atomic number 52.
Dvi-tellurium is, of course, polonium. To date, only PoO and PoO2 have been prepared. Implications for teaching (1) One implication of all this for the teaching of “pure” chemistry is that we need to do justice to the different kinds of understanding that the subject involves. In par...
a dwarf planet — may be divided into the smaller terrestrial planets of Mercury, Venus, Earth and Mars, and the larger gas planets of Jupiter, Saturn, Uranus and Neptune. While each of the larger planets have unique characteristics, they do share a number of similar traits with each other...
Litvinenko is on life support in University College Hospital having allegedly been poisoned with a potentially lethal dose of the heavy metal thallium polonium. His condition is apparently serious but stable and he is under 24-hour armed surveillance. The BBC claims that his condition could be the...
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A line of radioactive cosmetics introduced in 1930 Each element comes in varieties called isotopes whose atoms differ in the number of neutrons in their nuclei. You’ve probably heard of uranium-235 and, well, the polonium-210 that did in former KGB officer Alexander Litvinenko. The former is...
Franciumis a chemical element with the symbol Fr and atomic number 87. Prior to its discovery, it was referred to as eka-caesium. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain it appears in), has a half-life...