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PERIODICITY OF PROPERTIES

PERIODICITY OF PROPERTIES:

                    Periodicity of properties refers to the repetition of similar properties of elements as we move across a period or down a group in the periodic table. This is due to the periodicity of the electron configuration of the elements.

                    The periodic table is a chart that organizes the elements by their atomic number, which is the number of protons in the nucleus of an atom. The elements are also arranged by their electron configuration, which is the way that the electrons are arranged around the nucleus.

                    The periodic table is divided into periods and groups. Periods are the horizontal rows in the table, and groups are the vertical columns. As we move across a period, the number of protons and electrons in the atom increases by one, but the electron configuration stays the same. This means that the atoms become larger as we move across a period, and their properties change.

                    As we move down a group, the number of electron shells increases by one. This means that the atoms become smaller as we move down a group, and their properties change.

Here are some of the periodic trends in properties:

Atomic radius:

                    Atomic radius decreases from left to right across a period and increases from top to bottom down a group. This is because as we move across a period, the number of protons and electrons in the atom increases, but the number of electron shells remains the same. This means that the electrons are held closer to the nucleus, and the atomic radius decreases. As we move down a group, the number of electron shells increases, so the electrons are held farther from the nucleus, and the atomic radius increases.

Ionization energy:

                    Ionization energy is the energy required to remove an electron from an atom in its gaseous state. Ionization energy increases from left to right across a period and decreases from top to bottom down a group. This is because as we move across a period, the atomic radius decreases, which means that the electrons are held closer to the nucleus and are more tightly bound. As we move down a group, the atomic radius increases, which means that the electrons are held farther from the nucleus and are less tightly bound.

Electronegativity: 

                    Electronegativity is a measure of an atom's ability to attract electrons. Electronegativity increases from left to right across a period and decreases from top to bottom down a group. This is because as we move across a period, the nuclear charge increases, which means that the atoms have a stronger pull on electrons. As we move down a group, the shielding effect of the inner electron shells increases, which means that the atoms have a weaker pull on electrons.

Metallic character: 

                    Metallic character increases from top to bottom down a group and decreases from left to right across a period. This is because as we move down a group, the number of valence electrons increases, which means that the atoms have a greater tendency to lose electrons and form positive ions. As we move across a period, the nuclear charge increases, which means that the atoms have a stronger pull on electrons and are less likely to lose electrons.



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