Logged out
Access All our Essays in an Instant
Swap your work for FREE access, or pay £4.99 for instant access
The Periodic Table
Member rating: No Rating | Words: | Submitted: Mon Feb 07 2005
Page Preview
On the left is an image preview of every page of this document, and below are the first 150 words with formatting removed:
The Periodic Table was developed in stages; the first person that attempted to classify elements in relation to their atomic mass was Johann Döbereiner. Döbereiner noticed similar properties between known elements. Theses similarities occurred in groups of threes and were known as 'triads'. The atomic weight of the middle element in each triad is approximately an average of the others. In 1863 John Newlands put the known elements in order of atomic weight and noticed that every eighth element had similar properties, he called this the Law of Octaves. After about 20 elements the table became ragged and some elements had identical places whilst others were incorrect because of inaccurate weights. Furthermore Newlands left no gaps for any unknown elements. Dimitri Mendeleev amended some atomic weight values and left gaps for any undiscovered elements. Mendeleev predicted properties of five elements that should be discovered, within 15 years of his predictions...
Get instant access
- Instant, unlimited access to our documents in full
- Swap your work for free access, or pay £4.99
- To see the full version of this document and 151,744 others
