there isn't an eighth row in the Periodic Table of elements. The two rows at the bottom that aren't connected are actually part of the sixth and seventh row.
However, in a row, the last one on the far right would normally have the larger atomic radius.
The element in the 18th column that has the largest radius is radon. It has an atomic radius of 1.34 Angstrom.
Cesium (Cs), atomic number 55, has the largest atomic radius in period 6.Only francium (row 7) may be larger, but testing is difficult because francium does not exist in any meaningful amounts (maybe 30 g on the entire Earth).
See the Web Links to the left for the answer.The AntoineFrosturg.edu page has a graph of atomic radius versus atomic number.The HMCO.com page has an interactive feature where you can individually plot the atomic radius for each row or column of the periodic table.The other two sites have tables with the actual numbers for the atomic radii. Go to wikipedia.org and look up atomic radius, they have 2 charts for it.
Going down and to the left on the periodic table, atomic radius increases. Therefore, the smallest atomic radius is that of Helium (He), and the largest is that of Francium (Fr). Coincidentally, these are also the most and least reactive elements.
The radius of a cadmium atom is smaller than the radium of a mercury atom. The trend for atomic radius is that the radius becomes larger toward the left side of the row and toward the bottom of the group.
The largest element in a Period (row) will be on the right of that Period (i.e. an inert gas). The largest element in a Group (column) will be at the bottom of that group. Examples; Helium is larger than Hydrogen (Period 1) Krypton is larger than Potassium (Period 3) Francium is larger than Lithium (Group 1) Ununquadium is larger than Carbon (Group 3)
Cesium
Cesium (Cs), atomic number 55, has the largest atomic radius in period 6.Only francium (row 7) may be larger, but testing is difficult because francium does not exist in any meaningful amounts (maybe 30 g on the entire Earth).
Atomic radius decreases across a row (increasing positive charge in the nucleus causes electrons in the same energy level to "shrink" into the nucleus due to electrostatic attraction). This means that potassium has the largest atomic radius in period 4.
Rb is the largest, Li the smallest in the row above. Group 1 of the periodic table: Fr > Cs > Rb > K > Na > Li > H
The atomic radius decreases across a period from left to right and increases down in a given group. That means that since the lower the element is in a group, the larger the atomic radius will be. The atoms with the largest atomic radii are located in Group I and are at the bottom of groups.
An additional proton, in the same period (row) makes the radius smaller and the nucleus bigger. It also changes the element.
Going across a row in the peiodic table, the atoms have more protons and electrons causing a stronger attractive force, pulling the electrons closer to the nucleus, making the atomic radius decrease. As a new shell is added ( next row down) the atomic radius increases
Atoms size get smaller as you go across from left to the right in periods and gets larger down the group on the periodic table. For a given group, the largest atom is in period 7. For a given period, the largest atom is in group 1.
The elements with the smallest atomic radii are found in the top of the P block of the periodic table. Helium (He) has the smallest atomic radius. Francium, on the other side of the periodic table (very bottom of the S block), has the largest atomic radius.
See the Web Links to the left for the answer.The AntoineFrosturg.edu page has a graph of atomic radius versus atomic number.The HMCO.com page has an interactive feature where you can individually plot the atomic radius for each row or column of the periodic table.The other two sites have tables with the actual numbers for the atomic radii. Go to wikipedia.org and look up atomic radius, they have 2 charts for it.
The atomic number increases from left to right across a period (row). This is because the atomic number is the number of protons in the nuclei of the atoms of each element. No two elements have the same atomic number. It is the protons that define an element.
Going down and to the left on the periodic table, atomic radius increases. Therefore, the smallest atomic radius is that of Helium (He), and the largest is that of Francium (Fr). Coincidentally, these are also the most and least reactive elements.