Do you know about molecular and ionic compounds?
Answer:
You are asking two different questions. Ionic compounds are compounds that are made up of two different ions (one positively charged and one negatively charged). The ions are not bonded to each other in the same way hydrogen is bonded to oxygen in water (by covalent bonds or sharing of electrons), but rather by the attraction of the two oppositely charged ions. Most compounds that contain metal atoms are ionic. There are also certain types of polyatomic cations (positively charged ions) that can be used to recognize ionic compounds. The most common of these is the ammonium ion, NH4(+), and related organic ions.
Polar and nonpolar describe two different types of molecular compounds. Polar compounds have a slight imbalance of the electrons in some of the bonds of the molecules that result in one side of the molecule being slightly positive charged and another being slightly negative charged (dipole imply two poles, one positive and one negative in the same molecule).
Identify whether a molecule is polar or not requires several steps.
1. Determine the Lewis Dot structure.
2. Determine the 3D structure of the molecule, usually using VSEPR (or Valence Shell Electron Repulsion Theory).
3. If the molecule has polar bonds, the molecule may be polar.
Usually, bonds between atoms of different elements are polar to some extent (the O-H bond in water is polar and the Cl-Cl bond in chlorine is not).
4. Determine whether the polar bonds "completely cancel each other out". If they do, the molecule will be nonpolar, if they do not the molecule will be polar.
One way to determine if they cancel out is to draw arrows representing the polar bonds with the head of the arrow pointing to the more electronegative atom (as determined from position on the periodic table or a table of electronegatiities). Consider the arrows to be pushing or pulling on the central atom(s) in the molecule. If that pushing or pulling is not balanced and would cause the central atom to move, then the molecule would be polar.
Compare water (H-O-H) and carbon dioxide (O=C=O). Both have two polar bonds, however the water molecule is bent (104 degree bond angle), whereas, the CO2 molecule is linear (180 degree bond angle). The arrows representing the polar bonds in water would be pointing toward the oxygen. Since the arrows are off to one side of oxygen atom, they would make it move if they were pushing on it. Water is polar.
In carbon dioxide, the arrows point toward the oxygens again. Since they are directly opposite one another, the arrows representing the bonds would pull against each other at a 180 degree angle and would exacly offset each other, the carbon would not move. Carbon dioxide is nonpolar.
It takes some practice and a good model kit works helps (or you can view and manipulate 3D models of many compounds over the internet). I would encourage you to work with someone that is starting to get the hang of it if you can.
One last thought, molecular structure and polarity are crucially important. If water had the same linear structure that carbon dioxide has, it would be nonpolar. If it was nonpolar, it would not be able to dissolve ionic compounds (salts) that are essential to life.
Good luck.
Ionic compounds are usually made of a metal and nonmetal, usually making them polar as well. One has a stronger ionization than the other.
NaCl, KCl, CaCl...
Hmm... polar molecules generally dissolve in water such as sugar or ammonia, where as nonpolar don't, such as fats and oils, besides that, I don't think there is a simple way of finding out. I hope this helps!!
Think about it symetrically. If a molecule is symetrical (even on both sides) then it is non-polar, because electrons are not attracted to any particular pole of the electron.
On the other hand, if it is not symetrical, then it is polar, because electrons will be attracted to the pole with the less negativity.
This system will usually work, but it's not the technical definition of polarity.
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