As can be seen in the figures below, the atomic radius increases from top to bottom in a group, and decreases from left to right across a period. Thus, helium is the smallest element, and francium is the largest….Periodic Trends — Atomic and Ionic Radii.

An atomic radius is one-half the distance between the nuclei of two atoms. Atomic radii are measured in picometers (one picometer is equal to one trillionth of a meter). Hydrogen (H) has the smallest average atomic radius at about 25 pm, while caesium (Cs) has the largest average radius at about 260 pm.

Cesium

184 pm

So, in the end, we can conclude that nickel ions have a minimum radius. So, the correct answer is Option C. Note: While comparing the ionic radius, we should consider all the points.

K+

(A) Comparison of Atomic and Ionic Radius of Group 1 (IA, alkali metals) Elements

290 pm

Helium has the smallest atomic radius.

Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 ångströms. Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1–10 fm), and less than 1/1000 of the wavelength of visible light (400–700 nm).

Since potassium is located at the start of period 3, and bromine at the end of the same period, potassium will have a larger atomic radius than bromine, and thus the largest atomic radius of the four given atoms.

There is only one exception in the trend of atomic radi along the period. By normal trend atomic radius increases along a period however the atomic radius of noble gases is fgreter than the adjacent halogen atom.

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.

the noble gas configuration has been reached. Which is the best reason that the atomic radius generally increases with atomic number in each group of elements? The number of occupied energy levels increases.

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.

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.

As electrons are added to the valence shell, an extra proton (i.e fundamental, positively charged nuclear particle) is added to the element’s nucleus. As electrons add and Z the atomic number increases 1 by 1, nuclear charge WINS, and electronic radii contract.

Why does the atomic radius decrease from left to right? Electrons enter the same energy level, as protons and electrons are added the force between the protons and electrons increase. The electrons are pulled closer to the nucleus making the atom smaller.

increases; cause by electron shielding;The number of energy levels increases as you move down a group as the number of electrons increases. Each subsequent energy level is further from the nucleus than the last. Therefore, the atomic radius increases as the group and energy levels increase.

Experiments have shown that the first case is what happens: the increase in nuclear charge overcomes the repulsion between the additional electrons in the valence level. Therefore, the size of atoms decreases as one moves across a period from left to right in the periodic table.

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. Down a group, atomic radius increases.

Carbon belongs to group 14, and oxygen belongs to group 16. As from moving left to right, the atomic radius generally decreases because of the increase of effective nuclear charge. So, carbon has a larger radius than oxygen.

Fluorine D

The less valence electrons an atom has, the least likely it will gain electrons. Electron affinity decreases down the groups and from right to left across the periods on the periodic table because the electrons are placed in a higher energy level far from the nucleus, thus a decrease from its pull.

This is where the other periodic trends comes into play. As you move down a colomn (a group) of the periodic table, atomic radius increases. This means that Al ‘s atomic radius will be smaller than that of K , but bigger than that of C and O .

Atomic Radius (increases down the group)

An oxygen atom has more mass (weight) than a carbon atom because it has more protons and neutrons. Atoms are made up of protons and neutrons, which are heavy, and electrons, which are very light.