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What happens to the atomic size of the lanthanides with increase in atomic number?
- a)The radius remains unchanged
- b)The radius decreases
- c)The radius increases
- d)The radius first increases and then decreases
Correct answer is option 'B'. Can you explain this answer?
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What happens to the atomic size of the lanthanides with increase in at...
Atomic size of Lanthanides
The lanthanides are a group of 15 metallic elements in the periodic table, with atomic numbers ranging from 57 to 71. As we move across the series from La to Lu, the atomic number increases, causing changes in the properties of the elements. One of the significant changes is the atomic size, which is affected by the number of protons and electrons in the atom.
Decrease in Atomic Radius
The atomic radius of the lanthanides decreases with an increase in atomic number. This is because of the effective nuclear charge, which increases with the addition of protons in the nucleus. The electrons in the outermost shell experience a greater attraction towards the nucleus, causing the atomic size to decrease.
The shielding effect of the inner electrons, which reduces the attraction of the outer electrons towards the nucleus, remains constant. Therefore, the increase in the effective nuclear charge becomes the primary factor in the decrease of atomic size.
Consequences
The decrease in atomic size has several consequences. As the atomic size decreases, the metallic character of the elements increases. The lanthanides become more electropositive, and their reactivity with other elements increases. The melting and boiling points also increase as the atomic size decreases, as the atoms are held together more tightly due to the increased effective nuclear charge.
Conclusion
In summary, the atomic size of the lanthanides decreases with an increase in atomic number due to the increase in the effective nuclear charge. This decrease has significant consequences for the properties of the elements, including their metallic character, reactivity, and melting and boiling points.
The lanthanides are a group of 15 metallic elements in the periodic table, with atomic numbers ranging from 57 to 71. As we move across the series from La to Lu, the atomic number increases, causing changes in the properties of the elements. One of the significant changes is the atomic size, which is affected by the number of protons and electrons in the atom.
Decrease in Atomic Radius
The atomic radius of the lanthanides decreases with an increase in atomic number. This is because of the effective nuclear charge, which increases with the addition of protons in the nucleus. The electrons in the outermost shell experience a greater attraction towards the nucleus, causing the atomic size to decrease.
The shielding effect of the inner electrons, which reduces the attraction of the outer electrons towards the nucleus, remains constant. Therefore, the increase in the effective nuclear charge becomes the primary factor in the decrease of atomic size.
Consequences
The decrease in atomic size has several consequences. As the atomic size decreases, the metallic character of the elements increases. The lanthanides become more electropositive, and their reactivity with other elements increases. The melting and boiling points also increase as the atomic size decreases, as the atoms are held together more tightly due to the increased effective nuclear charge.
Conclusion
In summary, the atomic size of the lanthanides decreases with an increase in atomic number due to the increase in the effective nuclear charge. This decrease has significant consequences for the properties of the elements, including their metallic character, reactivity, and melting and boiling points.
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What happens to the atomic size of the lanthanides with increase in at...
The gradual decrease in the atomic and ionic radii of the lanthanides with an increase in atomic number is called lanthanide contraction. It occurs due to the poor shielding effect of the 4f electrons.
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What happens to the atomic size of the lanthanides with increase in atomic number?a)The radius remains unchangedb)The radius decreasesc)The radius increasesd)The radius first increases and then decreasesCorrect answer is option 'B'. Can you explain this answer?
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