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Atoms and Molecules

Updated on April 06, 2012
Our Best Guess
Our Best Guess


Like I menioned in my other post, anything that you can see with the naked eye or even the best microscope is a bundle of atoms too many to ever count. You can make an accurate guess as to how many there are - but that's still guessing. I likened it to counting the grains of sand on the beach - there are just too many to count.

But what do atoms and molecules really look like? What are they made of and how do they work? There are two main parts that chemists look at - three if you're a nuclear chemist or paying attention to isotopes. In an atom there is the nucleus and the electrons that orbit it. People have this image that it's like the solar system where the sun is the nucleus and the planets are the electrons. This is not entirely inaccurate, but it's not a good idea to embed this image in your mind.

We do not know exactly what an atom looks like, but we have a highly educated guess that is built off of large-scale models. Electrons orbit the nucleus (and there's a debate whether the word "orbit" is appropriate) in a harmonic way. So by studying sound and waves, scientists were able to derive what an electron should look like as it moves around the nucleus. Schrodinger even came up with an equation to map it out. See the image above of a simple electron cloud.

Protons and Electrons

Protons and electrons are the charged subatomic particles that define how an element reacts. Protons are the positively charged particles that are contained in the nucleus of an atom. Electrons are negatively charged and are far outside the nucleus. The size of the nucleus is incredibly small compared to the electron cloud around it. I once heard it likened to a pea in a football stadium.

Which element you're talking about is completely dependent on how many protons are in the nucleus. Hydrogen is the first element and atoms of this element have only one proton in the nucleus. Helium atoms have two protons in the nucleus. Lithium has three. Beryllium has four. So on and so on. If you look at a periodic table of elements, reading it left to right and top to bottom, you will see all the elements numbered off by how many protons they have in their nucleus.

A lot of people think of the four elements of wind, water, fire, earth. These are not elements to a chemist! No Bruce Willis shit or a fifth element here. Elements can be thought of as types of atoms, where the number of protons determines what element you're talking about.

Neutrons are heavy particles in the nucleus that hold no charge and don't play a significant role in simple chemistry. They do, however, mean that the weight of a nucleus will be greater than the number of protons contained in the nucleus. Long story. Irrelevant for now. Just thought I'd mention them.

So protons are heavy and positively charged. Electrons are tiny and negatively charged. When two atoms interact, it's mostly the electrons that do the interacting. The electrons are all around the atom and moving so fast that pinpointing a location is a bit impractical. Instead, we look at all the places it could be and map it out - and all those places combined look sort of like a cloud. That's why we refer to it as the "electron cloud". When two atoms get close enough to interact, the electron clouds of each are the first parts to touch each other.

Now a bit about energy again. Energy is god when it comes to particle interactions. Things tend to give off energy - objects fall, fast things slow down, sound gets quieter the farther from the source it gets... If it can move to lower energy levels, it will. If two atoms can lower their energy by sharing their electrons, they will share their electrons and kind of attach themselves to each other while doing so. This is refered to as bonding.

Massive flow of electrons from one place to another.
Massive flow of electrons from one place to another.


When two or more atoms bond, the result is a molecule! It's as simple as that, but not really. There are multiple ways atoms can bond together. One way is for them to share electrons evenly between the two - a perfect balance only happens with atoms of the same element. Another way is for them to share electrons unevenly - one atom holds the electrons more tightly than the other. Yet another way is for one atom to rip off an electron completely from the other atom, causing the stronger atom to have one more electron than proton and be negatively charged while the weaker has one less electron than proton and be positively charged - since negative and positive attract, the two charged atoms will stick around each other. And believe it or not, metals even have their own type of bond that is very similar to the first described.

Listing them off respectively as I described: Nonpolar covalent bond, polar covalent bond, ionic bond, and metallic bond.

Two oxygen atoms bound together (O2) share their electrons equally and have a nonpolar covalent bond. Two hydrogens bound to an oxygen (H2O - water) share electrons unevenly and have a polar covalent bond. A sodium attracted to a chloride (NaCl - table salt) literally has the electron ripped off and they have an ionic bond.

Metals are unique because an electron in the outer parts of the atoms is shared by all the atoms in that metal, which can be trillions upon trillions of atoms. The electrons are not assigned to any one atom and can flow around a bit like a fluid. That is why metals make the best conductors of electricity. That is what electricity is - a massive flow of electrons from one area to another. Pretty cool, huh?


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    • Constant Walker profile image

      Constant Walker 8 years ago from Springfield, Oregon

      Very cool! Query; If no one's actually seen an atom, how do we know for sure it is what we believe it is? How is something we cannot see studied, by it's interaction of things around it?

      BTW: As I'm looking at the periodic table of elements -per your suggestion, I've always wondered what those numbers mean!- I see that boron has 5 protons, and beryllium has 4. Doh!

    • Science Guru profile image

      Science Guru 8 years ago

      I stand corrected on the beryllium aspect. I have since changed the post. Thanks for the catch.

      A lot of what we know about the atom and the structure of it is from making a guess and testing it experimentally. Other aspects we can observe using equipment like UV-Vis spectrometers, where we don't necessarily see any one atom, but the behavior of billions and trillions. A man from New Zealand named Rutherford blasted gold with alpha particles (essentially helium nuclei) and discovered that a few bounced back or were deflected at odd angles - proof that the nuclei of the gold atom was incredibly small and dense, as well as positively charged. Newer experiments of similar nature involve particle accelerators that speed up nuclei to close to the speed of light and then smash them together and watch what's given off after the collision.

      It's a culmination of hundreds of years of slowly solving it, from guesses as far back as greek philosophers to alchemists from Arabia around the crusades to scientists in the early eighteen hundreds. We didn't have the current idea of the atom until after Einstein, Schrodinger, Bohr, Fermi, and a dozen other major scientists proved their work. De Broglie figured out that particles should have a wavelength that depends on their mass and energy, which was proven years later and incorporated into the model of the atom.

      We know the current image of the atom above is inaccurate, but it's our best guess for now and we have gotten far with it. A couple reasons we know it's inaccurate include: if electrons "orbit" the nucleus, they are accelerating towards it at all times - electrons that accelerate give off light and fall to lower levels of energy, which would eventually lead to them falling into the nucleus and being absorbed by a proton and resulting in the creation of a neutron. This doesn't happen, leading us to think electrons don't accelerate around the nucleus. Also, the wave forms we use to solve schrodinger's equation have nodes in the nucleus, which means the electrons pass through the nucleus without interacting much - and we know this doesn't happen since a proton would grab the electron as it passed through and result in the creation of a neutron. One man was able to come up with wave forms that didn't have nodes in the nucleus, but then he couldn't account for why the electron changes spin as it moves from one part of the electron cloud to another.

      After a while, we noticed that we could potentially go really far with the model we have right now. But we've noticed that we can only go so far before inaccuracies start holding us back. Scientists are still trying to solve it, but the emphasis is on reaching the limit of potential before the inaccuracies become too big to ignore. One theory I have on it is that even when we do solve the exact structure of the atom, governments will keep it from going public in order to maintain a balance of power or to gain an advantage at a later time. We may never know the truth.

    • dutch84 profile image

      dutch84 8 years ago

      you truly are the Science Guru of hubpages, aren't you

    • Constant Walker profile image

      Constant Walker 8 years ago from Springfield, Oregon

      Thanks, Sci-Guru, I actually understood most of that. As per governments hiding the truth... nothing new there. Knowledge is power.

      Dutch. I know, dizzying!

    • profile image

      reece 7 years ago

      how do atoms bond

    • Science Guru profile image

      Science Guru 7 years ago

      Reece, it's hard to describe how atoms bond. There's a combination of forces that govern the behavior of atoms and how they bond. I like to think of it as a tug of war for electrons. Some atoms "want" electrons more than others, some not at all. Anyway, when two atoms bond they are tugging for the electrons and they refuse to let go until some chemical reaction takes place. Sometimes the tug of war isn't much of a challenge and one atom rips the electrons off the other and the two bond as attracted oppposites.

    • profile image

      Hero Alexandra 6 years ago

      I'm wondering, and this is a pretty dim question but I am only 14 and still learning, do molecules share a nucleus as well as the electrons?

      Thank you.

    • Science Guru profile image

      Science Guru 6 years ago

      Hero Alexandra,

      Nope. They don't. The nuclei stay separate throughout all chemical reactions, including those that create molecules. Nuclei influence each other, but nuclei aren't shared.

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