Chemistry Drill of UN Exam 2011 SMA Paket 5

A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Common examples of elements are iron, copper, silver, gold, hydrogen, carbon, nitrogen and oxygen.
Save for the hydrogen and helium in the universe, which are thought to have been mostly produced in the Big Bang, most chemical elements are thought to have been produced by later processes.
These processes are divided into:
cosmic ray spallation (important for lithium, beryllium and boron, though some of these may have formed in the Big Bang), and
stellar nucleosynthesis which produces all elements heavier than boron (with carbon being the first of this series). The very heaviest elements (those beyond element 94, plutonium) decay with half lives too short to allow them to be observed naturally on Earth.











Downloading is the process of receiving data (usually in the form of files) from a system such as a web server, FTP server, mail server or other similar systems. Download is also an activity where one can obtain certain files on the Internet. The file can be downloaded manifold. There is a video file, mp3, document, and others. This blog serves the article and also some files to be downloaded for free and good.