SCH100 periodic table and trends.html

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Skip to main content Periodic table Elements in the periodic table are arranged in to rows (called periods) and columns (called groups). Elements in Groups 1 and 2 are also called s block elements: valent electrons fill in s orbitals. Elements in Groups 13 to 18 are also called p -block elements: valent electrons fill in p orbitals. Elements in Groups 1, 2 and 13 - 18 are called main group elements. Elements in Groups 3 - 12 are called transition metal because they have partially filled d- orbitals. They are also called d -block elements because valence electrons ae contained in d orbitals. f -block elements (also called Lanthanides and Actinides) have valent electrons filling in f orbitals. Elements in each group have similar valent electrons configuration (electrons in the outermost shell) and therefore similar properties.
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Periodic Trends of Atomic Parameters Atomic properties such as effective nuclear charge, atomic radii, ionization energies, electron affinity and electronegativity are important in accounting for the chemical properties of an element. Shielding: In atoms with more than one electrons, the effect of electron-electron repulsion depends on where the various electrons are located in the atom. electrons in the outer shell (higher n ) are pushed away by electrons in the inner shell (lower n ). As a result, the net nuclear charge (or effective nuclear charge, Z eff ) felt by an outer electron is substantially lower than the actual nuclear charge (Z). We say that the outer electrons are shielded from the full charge of the nucleus by the inner electrons. Electrons in the same shell (same n ) have an immediate effect in shielding the nuclear charge. Electrons in the outer shell (higher n ) do not shield the nuclear charge from the inner electrons (lower n )   In 1930, Slater formulated a set of rules for the effective nuclear charge felt by electrons in different atomic orbitals based on experimental data. The effective nuclear charge Z eff can be calculated by the following equation: Z eff = Z actual - S where, Z: atomic number (number of protons); S: Slater screening constant; The values of S are estimated as follows: o Write out the
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