Question

how do i know if something is an ion or not?

Answer 1

If it ionizes. ie. have positive & negative charge both, then it is said to be an ion
Al2O3 = Al3+ + O2-

Answer 2

is there any way to know by looking at the element? like how do i know if two molecules have ion-dipole force or somehting

Answer 3

Ions are atoms or molecules with an inherent imbalance of + and - charge (this might sound like dipoles, but it's not!). For example, an atom is an ion if it has an unequal number of protons and electrons (ie imbalance of charges) for example Cu2+ is missing 2 electrons compared to Cu, and Cu2+ has 2 more protons in its nucleus than it has electrons in its orbitals (both will have the same number of protons, since they are the same element). An atom with balanced + and - cannot be an ion. However, a molecule can also be an ion, if the total charge for that molecule is not balanced, (for example OH- has a total number of electrons that is one more than the total number of protons, so it has one extra electron. We can get more specific and say a cation is an ion with + charge, and an anion is an ion with negative charge. Now sometimes, you have molecules that overall, there is a balance of charge (these are not ions) but if the molecule has an unequal distribution of electrons (dipole! dipole! dipole!) then it will act like an ion, and participate in intermolecular interactions with other molecules that are either ions, or dipoles.

Answer 4

lg -here is a strange way to visualize this. Think of an atom or molecule as a boat, and the - or + charges as people with paddles who want to paddle the boat right(+) or left(-). If the atom or molecule is an ION then there are a fixed unequal numbers of paddlers on each side, so boat will always tend to drift off to one side. In DIPOLE, there can be an equal number of paddlers (+ and - charge), but for some reason, the paddlers don't get along very well, so for any given point on the boat, at any given time, one side is out paddling the other...

Answer 5

ohhh so as long as there is + or - it's an ion?

Answer 6

yes

Answer 7

what about polar molecules? what are they?

Answer 8

polar molecules are molecules with net dipoles, like Water for example. We know a molecule with balanced + and - is not an ion, but it can try to act like an ion, by having dipoles. To see if it will act like an ion by generating dipoles, we must look at the electronegativity of the participating atoms, and then at the overall symmetry of the distribution of charge. First, every covalent bond in a molecule may be polar or nonpolar, that simply depends on if the 2 participating atoms have very different electronegativities. If so, then the bond is polar, and electrons will tend to hang out more with the more electronegative atom, which creates a dipole, (reminder, these are vectors). But this one dipole doesn't automatically mean the molecule is polar. To detemine this we consider the structure of the entire molecule - if the charge is balanced (symmetrical) then even though it has unequal distribution of charge, and has dipoles, these are arranged to cancel eachother out, so that on the whole, there is no net dipole, and it is not acting like an ion. But if the distribution of dipoles is asymmetrical then the molecule is polar. So water H20 has a dipole because it has unequal distribution of charge, and is asymmetrical, and this creates a net dipole which accounts for the overall polarity of the molecule. If there was a symmetrical molecule, the net dipoles (which are vectors) can all cancel out, and the molecule would be non-polar even though it contains polar bonds and dipole moments between individual atoms.

Answer 9

im confused :( but wait....i think i recall somehting like if a molecule has zero dipole moment then it's non polar....so if it has a dipole moment...then it's polar....did i get it right?

Answer 10

pretty good! Dipoles arise from differences between atoms, and each dipole has its own dipole moment that can be calculated, but we can also total the dipoles (their moments actually) to see if the total dipole moment is zero (since dipoles are added like vectors). So Dipole moment is actually a vector you can calculate, µ = qr (where µ is the dipole moment vector, and q is the size or amount of charge, and r is the vector indicating the separation of charge). If you think back to physics, with forces, the net force is zero when all individual forces are balanced. Same with dipole vectors - if they all balance out then the molecule has net dipole moment of zero and is nonpolar.

Answer 11

yeah..the lone pair "balloons" really confuse me though when calculating for dipole moments :/

Answer 12

dipole moment is given by only polar compound i agree with this but sometimes dipole moment become zero as when u draw the direction of forces u ll find them anti[arallel to each other and @lgbasallote i think u hould give medal too to @lizcody1 as he/she tried to help u a lot..

Answer 13

Hmm, that's a good point lg, as far as I know, dipoles arise from unequal sharing of electrons that form a covalent bond (bonding electrons), but lone pairs are non-bonded, they just always hang out by a single atom (in theory) - I agree they are confusing!