Atomic Radius Increase Up Periodic Table: Why?

In summary, atomic radius is the distance from the center of an atom's nucleus to its outermost electron shell. Moving from left to right across the periodic table, the atomic radius decreases due to the increase in nuclear charge. However, moving down a group, the atomic radius increases as new electron shells are added. A larger atomic radius can make an element more reactive, as it is easier for outermost electrons to be removed or shared. While atomic radius generally decreases across a period, there are exceptions such as noble gases. Other factors that can affect atomic radius include the charge of the nucleus, number of electrons in the outermost shell, and electron shielding.
  • #1
nuby
336
0
If an atom with more protons have tighter electron orbitals than atoms with fewer protons, why doesn't the "atomic radius" decrease up the periodic table? Instead it increases, why is this?
 
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  • #2
Shielding. The inner electrons shield the nucleus from the outer electrons, so they do not have the full nuclear potential.

Furthermore, higher orbitals have very eccentric geometry which is included in what we define as the "size" of an atom.

Zz.
 
  • #3


The atomic radius refers to the distance between the nucleus of an atom and its outermost electron. While it is true that atoms with more protons have tighter electron orbitals, this does not necessarily mean that the atomic radius will decrease as you move up the periodic table.

One reason for this is the concept of shielding. As we move up the periodic table, the number of energy levels or shells increases, and the inner shells of electrons act as a shield for the outermost electrons. This shielding effect reduces the attractive force between the nucleus and the outermost electrons, causing the atomic radius to increase.

Another factor to consider is the effective nuclear charge. As we move up the periodic table, the number of protons increases, but the number of inner electrons also increases. This means that the outermost electrons experience a weaker effective nuclear charge, which also contributes to the increase in atomic radius.

Additionally, the size of the electron orbitals themselves also play a role. As we move up the periodic table, the size of the electron orbitals decreases, but the number of electrons in each orbital also increases. This results in a net increase in the size of the atom, leading to an increase in atomic radius.

In conclusion, while the number of protons does affect the tightness of electron orbitals, other factors such as shielding, effective nuclear charge, and orbital size must also be taken into consideration when explaining the increase in atomic radius up the periodic table.
 

1. What is atomic radius and how does it change across the periodic table?

Atomic radius is the distance from the center of an atom's nucleus to its outermost electron shell. As you move across the periodic table from left to right, the atomic radius decreases. This is because as you move across a period, the number of protons in the nucleus increases, resulting in a stronger pull on the outermost electrons, making the atom smaller.

2. Why does atomic radius increase as you move down a group in the periodic table?

Atomic radius increases as you move down a group due to the addition of new electron shells. Each new shell is further from the nucleus than the previous one, resulting in an increase in atomic radius.

3. How does atomic radius affect the reactivity of elements?

Elements with a larger atomic radius tend to be more reactive because their outermost electrons are further from the nucleus, making them easier to remove or share with other atoms. This is why elements on the left side of the periodic table, which have larger atomic radius, tend to be more reactive than elements on the right side.

4. Can atomic radius increase in a period?

No, atomic radius generally decreases as you move across a period. However, there are some exceptions to this trend, such as the noble gases which have a full outer electron shell and therefore have a larger atomic radius than the elements in the same period.

5. What other factors can affect the atomic radius of an element?

Other factors that can affect atomic radius include the charge of the nucleus (elements with more protons will have a smaller atomic radius), the number of electrons in the outermost shell (more electrons result in a larger atomic radius), and the presence of electron shielding (which can decrease the effective nuclear charge experienced by outer electrons, resulting in a larger atomic radius).

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