Comments on: Technetium Element Facts http://www.chemicool.com/elements Cooler Than Absolute Zero! Mon, 19 Nov 2012 20:12:52 +0000 hourly 1 http://wordpress.org/?v=3.5.1 By: Doug Stewart http://www.chemicool.com/elements/technetium.html#comment-2096 Doug Stewart Mon, 22 Oct 2012 14:02:59 +0000 http://www.chemicool.com/elements/?page_id=373#comment-2096 Hi Ashley, I guess you’re meaning the () around the element’s atomic weight. In technetium’s case: (98). This doesn’t mean the element is man-made, it means it has no stable isotopes. The number in parentheses is the longest-lived isotope.

For example, the element radon occurs naturally, but its atomic weight is given as (222) because all its isotopes are radioactive. The isotope of radium with the longest half-life is radium-222.

In technetium’s case the longest lived isotope is technetium-98, with a half-life of 4.2 million years.

]]> By: Ashley http://www.chemicool.com/elements/technetium.html#comment-2079 Ashley Mon, 22 Oct 2012 01:57:18 +0000 http://www.chemicool.com/elements/?page_id=373#comment-2079 I was wondering why Technetium’s average atomic weight is cited the same way the man-made’s elements are? I’m in high school, so please bear with me!!

]]>