This may present problems when rendering to non-visual media. Tables should not be used purely as a means to layout document content as Web-enabled pagers and phones) to handle tables. Mechanisms greatly assist users with visual disabilities, they make it possibleįor multi-modal wireless browsers with limited display capabilities (e.g., That non-visual user agents may more easilyĬommunicate heading information about the cell to the user. The HTML 4 table model allows authors to label each cell so TH element) or "data" (see the TD element). Table cells may either contain "header" information User agents to render the table incrementally rather than having to wait forĪll the table data to arrive before rendering. Printed, the head and foot information may be repeated on each page thatĪuthors may also group columns to provideĪdditional structural information that may be exploited by user agents.įurthermore, authors may declare column properties at the start of a tableĭefinition (via the COLGROUP and COL elements) in a way that enables Sections independently of the head and foot sections. UserĪgents may exploit the head/body/foot division to support scrolling of body Row groups convey additional structural informationĪnd may be rendered by user agents in ways that emphasize this structure. Table rows may be grouped into a head, foot, andīody sections, (via the THEAD, TFOOT and TBODYĮlements, respectively). Summary attribute) for the benefit of people using speech or A longer description may also be provided (via the into rows andĮach table may have an associated caption (see theĬAPTION element) that provides a short description of the table's Text, images, links, forms, form fields, other tables, etc. The HTML table model allows authors to arrange data - text, preformatted Column groups: the COLGROUP and COL elements. ![]() Not to miss out, element 102, Nobelium, No, is named in honor of Alfred Nobel, who set aside his vast fortune to establish Nobel Prizes. Mendeleev never received a Nobel Prize for his work, but element 101 was named Mendelevium, Md, after him. For instance they discovered phosphorus when they isolated it from urine. Over time these gaps have gradually been filled in as scientists unearthed new elements. Not only did Mendeleev arrange the elements in the correct way, but he also had the foresight to leave gaps for undiscovered elements. ![]() At that time, he had only 50 elements to arrange. He wrote the properties of the elements on pieces of card and rearranged them until he realised that, by putting them in order of increasing atomic weight, certain properties of elements regularly occurred. Then in 1869, a Russian scientist called Dmitri Mendeleev produced one of the first practical periodic tables. Several other attempts were made to group elements together over the coming decades. The earliest attempt to classify the elements was in 1789, when Antoine Lavoisier grouped the elements based on their properties into gases, non-metals, metals and earths. The discovery of other elements followed regularly and soon it became necessary to arrange them in some sort of order. However, the first scientific discovery of an element occurred in 1649 when Hennig Brand discovered phosphorous. Copper has been used by humans for as much as 7000 years and elements such as gold, silver, tin, lead and mercury have been known for many thousands of years.
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