Why don't ions form molecules?

Question

I read in my text book that ions are found in enormous collections of ions and they have no single bonding partner.

Why though? I mean, take NaCl for example, isn't Na's partner Cl? And why are other ions attracted to this pair? Don't these two complete each other? Why can't this pair be called a molecule? What connection to they have with other atoms, or even other Na's and Cl's? Weren't all the electrons already transfered? So what do these other ions want?

To tell you the truth, I don't really know much about chemistry. So help me out! :) What does it REALLY mean when an atom is charged? I mean, what can it do in this state?

Answer 1

An atom is charged when it loses or adds an electron. Recall that in neutral, uncharged atoms, there is an equal balance of positively charged protons and negatively charged electrons. If there is an imbalance - for example, if there are more protons than neutrons - you would have a charge (in my example, you would have a positive charge).

Another thing to recall is that when you have a charge, it radiates its charge all around it; since opposites attract (i.e. positive charges attract negative charges and vice versa), the positive charge would attract many negative charges. In turn, the negative charges would attract more positive charges.

In essence, then, NaCl is not a single compound because it's actually just a lot of Na+ and Cl- ions grouping up together. Below, I've typed out a diagram to illustrate what sodium chloride would look like... please note that "+" is the sodium ion (Na+) and "-" is the chloride ion (Cl-).


+-+-+-+-+-+-
-+-+-+-+-+-+
+-+-+-+-+-+-
-+-+-+-+-+-+
+-+-+-+-+-+-
-+-+-+-+-+-+

The reason why the formula is "NaCl" and not something like "Na32Cl32" (numbers subscripted) is because that is the empirical formula, not the molecular formula.

Recall also that this is not a covalent bond that Na and Cl are sharing; instead, they are just electrostatically attracted to each other. This is why salt dissolves so easily in water.

If you have any more questions, feel free to e-mail me! =)

Answer 2

Strictly speaking ions in SOLUTION (i.e. in a solvent, typically water) do not form molecules. In solid state, NaCl, or sodium chloride is a molecule.
Ions are elements that are charged; this means that they either have more or less electrons than the number of protons they have. Protons determine the element (which is also the atomic number). For example, sodium (Na) always has 11 protons. Sodium with 11 electrons has 0 charge, and is thus NOT an ion. However, sodium is often found as a +1 ion; that is it has 10 electrons (+11-10 = +1). When forming ionic compounds such as NaCl, sodium will tend to bond with ions that have a -1 charge, thus giving an overall 0 charge. Cl is one of these elements, and can easily have a -1 charge. However, sodium will also commonly bond with other -1 elements. NaBr, for example, is stable.

Get a good understanding of the quantum mechanics of chemistry, such a valences and molecular bonding, if you want to know more.

Answer 3

molecules are clusters of atoms that are held together by covalent bonds. ions in contrast are held together by electrostatic attraction. although, just to make things more complicated, ions are not necessarily single atoms, they can themselves be molecular, such as sulfate ion, (SO4)2-. you can think of normal molecules as ions that have a charge of zero. charge is an additive property: you simply add up the number of positively charge particles in the molecule (i.e. the protons in the atomic nucleus) and the negatively charged particles (electrons). because the electrostatic force is so powerful, large objects are always neutral (no charge) or very nearly neutral. so positive ions are always balanced by a number of negative ions such that the charge balances out (for example if the positive ions in a compound are +2, there will be twice as many negative ions so that the compound is neutral overall).

so what is the difference between an ionic and covalent bond? this has to do with a concept called electronegativity. each type of atom has a particular affinity or 'attracting power' for (valence shell) electrons, called the electronegativity. electronegativity increases across a group in the periodic table, so that metals are weakly electronegative, and halogens are strongly electronegative.

when metal and halogen atoms are paired together in a compound (for example NaCl), it is often the case that the halogen atoms attract electrons so strongly that they strip them from the metals completely, and form ions (which are bonded by ionic bonds) rather than sharing electrons in a covalent bond.

conversely, compounds where the atoms have only small differences in electronegativity are usually covalent, because the electrons tend to be shared between atoms, neither atom attracting the electrons so much that ions are formed. carbon compounds for example are usually covalent (since carbon is in the middle of the periodic table and has intermediate electronegativity, it can form covalent compounds with many different atoms, either weakly electronegative or strongly electronegative ones).

so to summarise ions in fact can BE molecules (or perhaps more correctly, molecular ions) but cannot form molecules (larger clusters) because of the way they are bonded. ionic bonds only ensure that the ions are near to each other in space, but the clusters have no particular three dimensional structure in solution (although in solid phase, they can form crystals, which if you stretch the definition of the molecule a little, could be though of as one giant molecule!). molecules (covalently bonded atoms, remember) do have particular three dimensional structures. this is most easily explained by valence shell electron pair repulsion theory (VSEPR). the basic concept in this theory is that covalent bonds consist of electron pairs which, because they are all negatively charged, repel one another and cause the their molecules to take on definite three dimensional shapes.

sorry, simple question, complicated answer. that happens a lot in science.

Answer 4

look up pH on wikipedia and take a glance at returned. beneficial, once you upload water to an acid, you have gotten diluted the acid and made it much less acidic. I nonetheless do no longer evaluate you savour what's happening there. assume protons, and delivers that wiki a study.