Answer:
As you move from left to right across a period, atomic radii decreases.
Explanation:
So, the last shell gets attracted closer, the atomic size also decreases.
Taking into account the definition of atomic radius, you move from left to right across a period, the atomic radius decreases.
First, you must know that the atomic radius represents the distance between the nucleus and the valence shell (the outermost). That is, the atomic radius is the distance between the nucleus and the electron furthest from it.
However, because the electron cloud that surrounds the nucleus has no definite limits, the size of an atom is determined by its interaction with the atoms that surround it. So the atomic radius can be defined as half the distance between the nuclei of two adjacent atoms.
On the other hand, you must first take into account that the effective nuclear charge is the charge that the nucleus should have so that, in the absence of other electrons, the attraction of the nucleus on the electron considered would be the same as the net attraction that the electron experiences. in the real atom.
As you move from left to right through a period of the periodic table, the number of internal electrons of each of the elements in that period remains constant, but the charge on the nucleus increases.
The electrons located in the outermost orbitals then feel a greater “effective nuclear charge”, being attracted with greater force towards the nucleus. This causes the atomic radius to decrease.
In other words, as you move to the right in the same period of the periodic table, even though the atomic number increases and therefore the number of electrons also increases, the atomic radius decreases. This is because, as Z increases, the number of protons also increases, so the attraction they exert on the electrons will also increase.
Then the so-called effective nuclear charge is increasing, and for this reason the nucleus attracts electrons with greater intensity. In this way, the atomic radius decreases.
In summary, you move from left to right across a period, the atomic radius decreases.
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