1 Atomic radius is a more definite and measureable way of defining atomic size. 2  It is the distance from the center of one atom to the center of another atom in a homonuclear diatomic molecule. 3  Rutherford led the way to determining the size of the atom with his gold foil experiment.
https://en.wikibooks.org/wiki/High_School_Chemistry/Atomic_Size
1 The trend in the periodic table is that as you move across the Periodic Table from left to right, the atomic radii decrease. 2  This trend is not as systematic for the transition metals because other factors come into play.
https://en.wikibooks.org/wiki/High_School_Chemistry/Atomic_Size
Whether you choose to use van der Waals radii or metallic radii as a measure of the atomic radius, for metals the ionic radius is smaller than either, so the problem doesn't exist to the same extent. It is true that the ionic radius of a metal is less than its atomic radius (however vague you are about defining this).
http://chemguide.co.uk/atoms/properties/atradius.html
The number of electrons are increasing, but in a particular way. We know that as the number of electrons increases going across a period, there is more pull of these electrons toward the nucleus. However, with the d −electrons, there is some added electron-electron repulsion.
https://en.wikibooks.org/wiki/High_School_Chemistry/Atomic_Size
ATOMIC AND IONIC RADIUS This page explains the various measures of atomic radius, and then looks at the way it varies around the Periodic Table-across periods and down groups. It assumes that you understand electronic structures for simple atoms written in s, p, d notation.
http://chemguide.co.uk/atoms/properties/atradius.html
ATOMIC RADIUS Measures of atomic radius Unlike a ball, an atom doesn't have a fixed radius. The radius of an atom can only be found by measuring the distance between the nuclei of two touching atoms, and then halving that distance.
http://chemguide.co.uk/atoms/properties/atradius.html
Considering all the information about atomic size, you will recognize that the largest atom on the periodic table is all the way to the left and all the way to the bottom, francium, #87, and the smallest atom is all the way to the right and all the way to the top, helium, #2.
https://en.wikibooks.org/wiki/High_School_Chemistry/Atomic_Size
The atomic radius is used to describe the size of an atom. Getty Images. Atomic Radius Definition: The atomic radius is a term used to describe the size of the atom, but there is no standard definition for this value. Atomic radius may refer to the ionic radius, covalent radius, metallic radius, or van der Waals radius.
http://chemistry.about.com/od/chemistryglossary/a/atomicradiusdef.htm
Choosing the right atomic radius to compare with This is at the heart of the problem. The diagrams in the box above, and similar ones that you will find elsewhere, use the metallic radius as the measure of atomic radius for metals, and the covalent radius for non-metals.
http://chemguide.co.uk/atoms/properties/atradius.html
These factors are: 1  The number of protons in the nucleus (called the nuclear charge). 2  The number of energy levels holding electrons (and the number of electrons in the outer energy level). 3  The number of electrons held between the nucleus and its outermost electrons (called the shielding effect).
https://en.wikibooks.org/wiki/High_School_Chemistry/Atomic_Size
describe one way in which atomic radius is defined
The radius of an atom can only be found by measuring the distance between the nuclei of two touching atoms, and then halving that distance.