which element in periodic table has smallest atomic radius? and which has the largest?
821309
Smallest is Hydrogen, largest would be, although it hasn't been created yet, element 121 also called Unbiunium according to IUPAC nomenclature. I say that because that is the largest element that would be able to be produced using current particle accelerators and colliders.
573382
Magnesium is the 12th element (atomic number 12).\n\nCarbon is the 6th element, but has an atomic mass of 12.
948794
protons is the atomic number\nvalence electrons corresponds to this:\nGroup 1 (I) (alkali metals) :1\nGroup 2 (II) (alkaline earth metals) :2\nGroups 3-12 (transition metals) :1 or 2\nGroup 13 (III) (boron group) :3\nGroup 14 (IV) (carbon group) :4\nGroup 15 (V) (nitrogen group) :5\nGroup 17 (VII) (halogens) :7\nGroup 18 (VIII or 0) (noble gases) :8\n\n\nEvery element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons. It goes down the periodic table like that. At this time, the maximum number of electron orbitals or electron shells for any element is seven.
973323
well, since there is only one element that can form a tri-atom (Iodine) I would say monoatomic elements would be the opposite, but this is a very ill-defined question.
570306
1.ATOMIC NUMBER\n2.ELECTRON\n3.SHELL\n4.ORBIT
945020
If you have your periodic table handy, look at the key for the table, where it will tell you which corner of each element's block has the atomic radius.  You will notice that atomic radius tends to increase as you go down the rows of the table.  Makes sense; More electrons means a larger atom.  As you go from right to left, however, you will see that, in any one row, the radius decreases until you get to about the middle of the row; then the radius begins to increase with the atomic weight.  On any row, the element at the left end (lower atomic weight) has a larger diameter than the one on the right end (higher atomic weight).  All of this out of the way, Beryllium is larger than Carbon, which is in turn, larger than Nitrogen.
170267
An atom is the smallest unit of any observable thing you can have. Atoms make up almost everything we can see.\n\nIt's name is Greek for 'Indivisable' but we have since found that atoms are made of protons, neutrons and electrons (and the first two are made of even smaller particles).\n\nAn element is a substance that is entirely comprised by only one type of atom. Gold, Tin and Oxygen are elements because they are made entirely of Gold, Tin and Oxygen atoms.\n\nMolecules and Compounds are similar in that they are made up of two or more atoms of different elements in a precise and defined ratio. Atoms in compounds can be ionically bonded. Molecules are, generally, covalently bonded.
469512
an atom- it is the smallest possible particle of an element that retains the properties of that element.\n\nan atom, being the smallest particle of an element is still composed of smaller particles: \n          • protons - particles with a weight or mass of 1 \n            amu (atomic mass unit) and has 1 positive \n            charge \n          • neutrons - particles with 1 amu and no charge \n            (neutral) \n          • electrons - particles with almost no mass \n            (almost 0 amu) and has 1 negative charge
824841
cell, chromosome, gene, nucleotides, base subunit, atom, nucleus\n(biggest to smallest)\n\ndepending on the question referring to the atomic nucleus not the cellular one\n\nif it referrs to the cellular nucleus it is smaller than cell, bigger than chromosome
223202
goto http://www.webelements.com/ or better stillhttp://www.schoolscience.co.uk/periodictable.html run over the element with your mouse it tells you what it is
910938
Na+ and K+ (both group 1)\nCa2+ and Mg2+ (both group 2).\nNa+ and Mg2+ have the electron arrangement of neon, and the other two that of argon.\nIonic radius decreases from left to right, and increases top to bottom, so K+ is the largest of all these.\nElectronegativity increases upwards and to the right of the Periodic Table, so Mg has the highest value of these four.
290665
3.45×10^−25 kg = Lead-208 atom, the heaviest stable isotope known\n\ncheck here http://en.wikipedia.org/wiki/Orders_of_magnitude_(mass) good luck
402942
An atom is stable when it has a full valence (outer) electron shell.  For the first row on the periodic table, the outer (and only) shell can hold up to 2 electrons.  For the next two rows, the atoms' outer shells can hold up to 8 electrons.  The next two can hold up to 18.\n\nAtoms like sodium, in column 1 of the periodic table, have one electron in its valence shell.  It is very reactive, since it wants to get rid of this extra electron so that its outer shell can be full.\n\nAtoms like chlorine, in the second last column, have one electron missing from their valence shells.  They are also very reactive, since they want to accept an electron to fill the outer shell.\n\nNoble gases are almost totally unreactive, since they have the unique property of having full outer shells without having to give away or accept any electrons.
693223
Yes an atom is the same as an element.  A single atom is the smallest particle of an element.  There are 118 different elements in the periodic table. For example, a Hydrogen atom is one proton and one electron.  The next element in the periodic table is Helium, it has one proton, one neutron and one electron.  Each of these atom examples represent their own element.  So you see a single atom does represent it's own particular element, as discussed in the Hydrogen and Helium examples.
52246
The the atomic number of an element tells you the number of protons and electrons. You can use this fact and say that the element with the largest atomic number has the largest nucleus. Each elements' nucleus would be bigger than the one before, but not by much.\n\nDepending on what source you use, that could be element number somewhere between element number 92 and 118. \n\nYou could also say that the more electrons an atom has, the further out its electron orbitals go out. Meaning the atom is bigger, as well as its nucleus.
809795
Yes, helium will result but so will something else.  Elements are arranged in the periodic table according to their atomic number.  The atomic number is the number of protons in the nucleus.  So, Ra has an atomic number of 88.  So, it loses two protons (neutrons don't count in this calculation) so the new atom's atomic number is 86 (88 minus 2).  Look at a periodic table and the answer will be whatever atom has an atomic number of 86.
798559
positive ions are formed by removing electrons from the atoms and hence the ionic radius for positive ion is always less than that of atomic radius