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  2. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    The atomic number increases within the same period while moving from left to right, which in turn increases the effective nuclear charge. The increase in attractive forces reduces the atomic radius of elements. When we move down the group, the atomic radius increases due to the addition of a new shell. [5] [6] [7]

  3. Lanthanide contraction - Wikipedia

    en.wikipedia.org/wiki/Lanthanide_contraction

    The lanthanide contraction is the greater-than-expected decrease in atomic radii and ionic radii of the elements in the lanthanide series, from left to right. It is caused by the poor shielding effect of nuclear charge by the 4f electrons along with the expected periodic trend of increasing electronegativity and nuclear charge on moving from left to right.

  4. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    Nonmetallic character increases going from the bottom left of the periodic table to the top right. The first periodic table to become generally accepted was that of the Russian chemist Dmitri Mendeleev in 1869; he formulated the periodic law as a dependence of chemical properties on atomic mass.

  5. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    As atomic number increases, shells fill with electrons in approximately the order shown in the ordering rule diagram. The filling of each shell corresponds to a row in the table. In the f-block and p-block of the periodic table, elements within the same period generally do not exhibit trends and similarities in properties (vertical trends down ...

  6. Atomic radius - Wikipedia

    en.wikipedia.org/wiki/Atomic_radius

    increases the atomic radius nuclear charge: attractive force acting on electrons by protons in nucleus: atomic number: increase along each period (left to right) decreases the atomic radius shielding: repulsive force acting on outermost shell electrons by inner electrons: number of electrons in inner shells: reduce the effect of nuclear charge

  7. Mass number - Wikipedia

    en.wikipedia.org/wiki/Mass_number

    The mass number should also not be confused with the standard atomic weight (also called atomic weight) of an element, which is the ratio of the average atomic mass of the different isotopes of that element (weighted by abundance) to the atomic mass constant. [9] The atomic weight is a mass ratio, while the mass number is a counted number (and ...

  8. Mass–energy equivalence - Wikipedia

    en.wikipedia.org/wiki/Mass–energy_equivalence

    The mass of an atomic nucleus is less than the total mass of the protons and neutrons that make it up. [15] This mass decrease is also equivalent to the energy required to break up the nucleus into individual protons and neutrons. This effect can be understood by looking at the potential energy of the individual components.

  9. Polarizability - Wikipedia

    en.wikipedia.org/wiki/Polarizability

    Generally, polarizability increases as the volume occupied by electrons increases. [9] In atoms, this occurs because larger atoms have more loosely held electrons in contrast to smaller atoms with tightly bound electrons. [9] [10] On rows of the periodic table, polarizability therefore decreases from left to right. [9]