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The periodic table is a chemistry reference that organizes all known elements in an informative grid. It provides information about the arrangement of electrons in atoms, the number of protons and electrons in each element, and the number of protons plus neutrons. Elements in the same row have the same number of energy levels, while elements in the same column have the same number of electrons in their outermost energy level. The periodic table also indicates the atomic number, atomic symbol, atomic mass, and mass number of each element.
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Describing the Periodic Table • The periodic table is a chemistry reference • It arranges all the known elements in an informative grid • Elements are arranged left to right and top to bottom in order of increasing atomic number • This order usually coincides with increasing atomic mass
Describing the Periodic Table • The Table's pattern and arrangement shows the arrangement of electrons in the atom. • Elements have different atomic numbers - the number of protons or electrons increases up the table as electrons fill the shells. • Elements have different atomic masses - the number of protons plus neutrons increases up the table.
Describing the Periodic Table • Rows - elements of each row have the same number of energy levels (shells). • Columns - elements have the same number of electrons in the outermost energy level or shell (one to eight).
Describing the Periodic Table • The different rows of elements are called periods. • The period number of an element signifies the highest energy level an electron in that element occupies
Describing the Periodic Table • The different columns of elements are called groups or families • Elements in the same family have similar properties
Interpreting the Periodic Table • Every table has:
Interpreting the Periodic Table Atomic Number The number of protons in an atom tells what element it is. The number of protons in an atom is referred to as the atomic number of that element.
Interpreting the Periodic Table Atomic Symbol:The atomic symbol is one or two letters chosen to represent an element ("H" for "hydrogen," etc.). These symbols are used every where in the world Usually, a symbol is the abbreviation of the element or the abbreviated Latin name of the element.
Interpreting the Periodic Table Atomic Mass:The atomic mass is the average mass of an element in atomic mass units ("amu"). Though individual atoms always have a whole number of amus, the atomic mass on the periodic table is shown as a decimal number because it is an average of all the isotopes of an element.
Interpreting the Periodic Table Mass Number:The sum of the protons and neutrons that make up that nucleus. The mass number is different for each isotope of an element.
