The period Periodic Patterns- Review
Describe the structure and layout of the periodic Table, and describe and explain, the general trends that are observed on crossing periods and descending groups.
The periodic table is one of the most important chemistry references, It arranges all the known elements in an informative and organized way The rows of the periodic table of elements are called periods, and the columns are called groups. Each box in the table represents an element by its chemical symbol, along with its atomic number and its average atomic mass in atomic mass units. The periodic table is arranged by increasing atomic numbers-the number of protons an element contains. (3,7)
There are 112 known elements, of which about 90 occur naturally on Earth. Uranium, with an atomic number of 92, was the last naturally occurring element discovered and elements with atomic numbers higher than 92 are man-made.
The chemical symbols in the periodic table are one-letter or two lettered abbreviations symbols e.g C for Carbon and He for helium. The first letter is always a capital letter, and the second is always in lowercase. Sometimes the two-letter symbols indicate the first and second letters of the element's name, but this is not always the case platinum is Pt. Elements 110 through 112 have yet to be named and so are given the three-letter symbols Uun, Uuu, and Uub. (4)
The periodic table has seven rows called periods and 18 columns. The columns are put together in terms of the element family. Hydrogen, even though it is a non-metal, and alkali metals are elements of group I, these elements usually have +1 charge in compounds. Each oxygen atom combines with two atoms of elements in Group 1. Alkaline earth metals are elements of group 2. These elements usually have +2 charge in compounds and each atom of oxygen combines with one atom of any element in Group 2. Group 13 is the column including and below boron. All of these elements combine...