is amounium a positive polyatomic ion or is it negative?
406261
Nitrogen has five unshared electrons , in ammonia 3 hydrogen atoms with nitrogen  covalently bonded remaining 2 unshared electrons and for that it is basic , when fourth hydrogen atom bonded to nitrogen of ammonia the 2 electrons from Nitrogen bonded to proton , and that bond in known as dative bond, so NH$ is a positive ion for that reason.
980772
A negative ion will be larger than the atom; a positive ion will be smaller than the atom.
841477
Cations are positive, and are attracted to the cathode, which is negative.
976855
Ions are basically charged atoms. The formula of an ion can be found out if you have the valency of the atom. You can figure out the valency of any atom by finding the group at which the atom is located in the periodic table. For example, Sodium (Na) is located in group 1A of the periodic table. Hence the valency is +1. The formula of the sodium ion would be Na+1.\n\nHope that helps!
10055
The radius of a positive ion will be smaller than that of a neutral atom.\n\nThe postive ion will be missing an electron that would have otherwise been occupying an orbital on the outside, therefore reducing the size of the atomic radius.
217978
Barium +2 is a positive ion.  It belongs to the alkaline earth metals group together with Beryllium, Magnesium, Cesium and Francium.
781553
a typical metalic atom takes a positive charge when it becomes an ion.  that means that it loses its valence electrons.  that means the radius is smaller in the ion than in the atom.
696955
larger...a negative ion has an electron added that the neutral atom does not have.
786992
b) small fraction of the maximum number of possible hydronium ions, H3O+.\n\nHNO2 + H2O <===> H3O+ + NO2-
1094903
Positive ions (Cation) are formed by a neutral atom losing electron(s), and Negative ions (Anion) are formed by atom gaining electron(s).  \n\nThe exact number of electrons an atom gains or loses are predictable.  Atoms gain or lose electrons so that they turn isoelectric with the closest neighboring Noble Gas.
634552
an ion with both acidic and basic part
35463
To have a net dipole moment (a positive end and a negative end), a species has to have some charge (partial or full) and have some asymmetry.\n\nMany (not all) ions are spherically symmetric (a metal ion, for instance--Na+).\n\nHowever, hydroxide ion (HO-) has asymmetry along the H-O bond, so it can have a net dipole.
165927
Positive and Negative ends of a molecule depend upon the electornegativity of the atoms of the molecule. Lets take a simple example of water here. H2O. \n\nOxygen is water is bound to 2 Hydrogen atoms. Oxygen is highly electronegative. So, it pulls the electrons in the O - H bond towards itself partially. So, this creates a partial negative charge on it and also a partial positive charge on Hydrongen.\n\nElectronegativity actually means "the ability of an atom to pull a lone pair of electrons towards itself". Electronegativity depends on the number of electrons present in the outermost shell. \nEx: Sodium has 1 electron in the outermost shell. So, its tenedecy to release this electron and get to a stabler configuration is more than gaining electrons further. But, in case of Chlorine, there are 7 electrons. It needs just 1 more electron to attain stable configuration. So, Chlorine tends to pull electrons towards it and therefore Chlorine is highly electronegative. \n\nNow, looking at the molecules u have given...\nNitrogen is highly electronegative. It has 3 unpaired electrons in its outermost shell, but it wud still go ahead and grab a few more to get to a fully filled state. So, in NH3, N would be partially negative and H would be partially positive. \n\nSo, is the case in HCN too. Cyanide ion (CN-) is a highly electronegative ion and therefore acts as the negative end. \n\n\nHope this information helps.
745401
There are two rules to use:\n1) The lattice energy between ions of opposite charge is strongest when the ions are small.\n2) The lattice energies  increase rapidly as the charge on the ion becomes larger.\n\nThe first rule implies that  LE(PbF2) > LE(PbCl2), in absolute value.\nThe second implies that   LE(PbF4) > LE(PbF2) and  LE(Pb2O3) > LE (PbF4)\nTherefore we have  LE(Pb2O3) > LE (PbF4) > LE(PbF2) > LE(PbCl2)  still in absolute value.\n\nConclusion:  3c 2d 1a 2b
1001444
As an ion, oxygen is negative.  As a molecule, 02 is neutral.  \nAn an ion, hydrogen is positive.  As a moleclue, H2 is neutral.
694929
The alkali metals, also known as Group 1.  They are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr).  The single valence electron is so easily given away that the elements lower down in the group react explosively with water.  Because they are so highly reactive, they are not found in elemental form in nature, only as ionic compunds.  They are stored under mineral oil to prevent reactions with the moisture in air.\n\nHydrogen is also in Group 1, but its single electron is held very close to the nucleus (a single proton), which means that the electron is not easily given away.  Hydrogen can form a positive or negative ion, because it can also easily accept a second electron to fill its valence shell.  Thus, it is not an alkali metal and is not a member of the family you are asking about.  However, under extremely high pressure, as occurs near the core of Jupiter, hydrogen does take on a metallic structure and behaves as an alkali metal.
27625
Typically the metals and hydrogen. Non-metals usually give negative ions.