Table of Contents
What is the periodic trend of atomic size?
Atomic size gradually decreases from left to right across a period of elements. This is because, within a period or family of elements, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged.
How does atomic size increases or decreases?
As we move from left to right in a period , number of electrons in shell increase , so effective nuclear charge ( force of attraction between nucleus of atom which has +ve charge and electrons which have -ve charge) increases so shells are closer to nucleus and atomic size is less .
Why does the atomic size increase from left to right?
This is because the number of protons increase moving to the right of the row. As the number of protons increase, the nucleus of the atom becomes more positively charged. The increase in positive charge increases the attraction between the nucleus and the electrons of the atom.
What affects atomic size?
The actual trends that are observed with atomic size have to do with three factors. These factors are: The number of protons in the nucleus (called the nuclear charge). The number of energy levels holding electrons (and the number of electrons in the outer energy level).
Why does the trend for atomic size occur?
In general, atomic radius decreases across a period and increases down a group. Down a group, the number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital. This results in a larger atomic radius.
Where does atomic size increase?
The atomic radius of atoms generally increases from top to bottom within a group. As the atomic number increases down a group, there is again an increase in the positive nuclear charge. However, there is also an increase in the number of occupied principle energy levels.
How does atomic size change with the increase in atomic number?
Increase in atomic number leads to an increase in the number of protons and electrons in the atoms. Due to the large nuclear charge (positive charge on the nucleus), the electrons are pulled in more close to the nucleus and the size of atom decreases.
How does atomic size vary on the periodic table?
Atomic size decreases across a Period from left to right as we face the Table, but INCREASES down a Group, a column of the Periodic Table. Atomic size is influenced by (i) nuclear charge, Z , and by (ii) shielding by other electrons.
What increases atomic radius?
The gain of an electron adds more electrons to the outermost shell which increases the radius because there are now more electrons further away from the nucleus and there are more electrons to pull towards the nucleus so the pull becomes slightly weaker than of the neutral atom and causes an increase in atomic radius.
What determines atomic size?
Atomic size is the distance from the nucleus to the valence shell where the valence electrons are located. There are three factors that help in the prediction of the trends in the Periodic Table: number of protons in the nucleus, number of shells, and shielding effect.
Why does atomic size increase in a group?