The atomic size of the elements in the periodic table
The atomic radius is used as a measure for the atomic size of the atom , and its measuring unit is picometre ( Pm ) , The picometre is part from million of million part of a metre .
The atomic size decreases in the periods by increasing the atomic number ( from the left to the right ) , due to the increase of the attraction force between the positive nucleus , and the outermost electrons .
The atomic size for the elements of the same group is directly proportional to the atomic number , The atomic size increases in the groups , by increasing the atomic number ( from up to down ) , due to the increase of the number of the energy levels occupied by the electrons .
The nucleus is positively charge as it contains the protons , and the neutral neutrons , In the modern periodic table , You notice that the largest atom of the elements in size is cesium atom , and the smallest one is fluorine .