Table of Contents
An Introduction to Modern Periodic Table
The modern periodic table is a table of the chemical elements arranged in order of increasing atomic number. The table is based on the electron configurations of the atoms.
The modern periodic table is divided into periods and groups. The periods are horizontal rows and the groups are vertical columns.
The elements in a period are all in the same energy level. The elements in a group are in different energy levels.
The elements in a period are all in the same row on the table. The elements in a group are in different columns on the table.
The modern periodic table is also arranged in order of increasing atomic weight.
Elements of the Modern Periodic Table
The modern periodic table is a chart that organizes the chemical elements in order of increasing atomic number. The table is divided into several rows and columns, with each element represented by a square box. The elements are arranged in order of increasing atomic number in the rows, and the columns are arranged in order of increasing chemical properties.
The modern periodic table was first developed in 1869 by chemist Dmitri Mendeleev. Mendeleev organized the elements in order of increasing atomic weight and noticed that certain properties of the elements seemed to repeat themselves at regular intervals. He then used this information to develop a periodic table that organized the elements in order of increasing chemical properties.
Periodic Trends in the Modern Periodic Table
The modern periodic table is based on the electron configuration of atoms. It is arranged in order of increasing atomic number so that the elements are easy to find. The periodic table is also divided into periods and groups.
Periods are horizontal rows in the table. The elements in a period have the same number of electron shells.
Groups are vertical columns in the table. The elements in a group have the same number of electron shells in their outermost shell. This is called the electron configuration.
Number of Shells
The number of shells an animal has is a reflection of its internal anatomy. Most animals have a backbone which supports a central nervous system. This central nervous system is surrounded by a protective bony casing called the skull. Animals with a backbone also have a second protective casing around the spinal cord called the vertebral column. This column is made up of small bones called vertebrae. The number of vertebrae in an animal’s column is directly related to the number of shells it has.
Some animals, like earthworms, do not have a backbone. They instead have a series of small, flexible bones called ribs. These animals do not have a skull or a vertebral column and, as a result, do not have any shells.
Valence Electrons and Valency
Valence electrons are the electrons in the outermost shell of an atom. The number of valence electrons an atom has determines its valency. The valency of an atom is the number of atoms of another element it can combine with to form a molecule.
Atomic Size (Atomic Radius Periodic Table)
The atomic size (atomic radius) of an atom is the distance from the center of the atom to the outermost electron.
The atomic size of an atom is different for different elements.
The atomic size of an atom is larger for the elements in the lower part of the periodic table and smaller for the elements in the upper part of the periodic table.
The atomic size of an atom is smallest for the elements in the group 1A (the alkali metals) and largest for the elements in the group 8A (the noble gases).
Metallic & Non – Metallic Character
istics
Metallic materials have a shiny surface and a characteristic metallic luster. Non-metallic materials do not have a shiny surface and they lack a metallic luster.
Melting Point
The melting point of a substance is the temperature at which the solid and liquid phases are in equilibrium.
Ionization Enthalpy/ Ionization Energy
The ionization enthalpy or ionization energy is the energy required to remove an electron from a gaseous atom or molecule.
Electron Affinity
The electron affinity of an atom is the energy released when an electron is added to a neutral atom to form a negative ion.
The electron affinity of chlorine is 349 kJ/mol.
Electronegativity
The electronegativity of an atom is a measure of how strongly it attracts electrons to itself. The higher the electronegativity of an atom, the more it will pull electrons away from other atoms.
The electronegativity of an atom is quantified by the Pauling scale. The higher the electronegativity of an atom, the higher its electronegativity value on the Pauling scale.
The most electronegative atom is fluorine, with an electronegativity of 4.0 on the Pauling scale.
