Periodic Table Homework

In 1875, French scientist Lecoq de Boisbaudran discovered gallium.

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There are 18 groups (columns) in the periodic table.

Group 1 (also known as the alkali metals) is the column on the far left of the table.

The rows are called PERIODS and the columns are called GROUPS.

Hydrogen (H) is the first element in the periodic table because it has just one proton in its nucleus.

The periodic table has been used by chemists to observe patterns and relationships between elements.

There are 3 main groups in in the Periodic Table; metals, metalloids, and nonmetals. There are also many other patterns and relationships.The Roman numeral names were used in most of the 20th century.In 1990 the International Union of Pure and Applied Chemistry (IUPAC) decided to use the new system with Arabic numerals, to replace the two old group systems that used Roman numerals.Gallium is a soft, silvery metal with a melting point of 29.8ºC (85.6ºF).This chemist was convinced there was an order to the elements.The extra particles make the atom heavier and the extra shell of electrons makes the atom take up more space.An astronaut’s visor is gold-plated to reflect sunlight.Helium (He) is second, because it has two protons, and so on. Often, each group is given a particular colour so that it is easy to pick out all the elements that belong to a particular group.As well as a name, each element has a symbol, a shorthand way of writing the element in chemical equations.The atomic number of an element is the same as the number of protons in that particular nucleus of an atom.In the periodic table the elements are arranged into periods and groups. Elements in a period have consecutive atomic numbers.

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