How do atoms form molecules necessary for life?
This is an important subject for science fiction because if atoms couldn’t form molecules we wouldn’t exist because we’re composed of large molecules called proteins.
An atom, as you should know, is composed of protons and neutrons packed together in a tiny, tiny nucleus with a swarm of electrons flying around in orbits or shells around it. The nucleus is so tiny and the electron shell around it so large in comparison, we are essentially made out of mostly space. This is the illusion of reality. We think of solid objects as being . . . well, solid, but in effect they aren’t. They’re mostly space. This sounds crazy but it’s true because of the weirdness of quantum physics. The fact is that solidness comes from the fact that electrons are negatively charged and like charges oppose or repel. Thus, since atoms have electron shells, they exert an opposing force on other atoms that approach. This is the illusion of solidness that we experience.
If that’s the case, how the heck do atoms combine to form a molecule, which is a group of atoms connected together by bonds? That’s where chemistry comes in. Given enough energy in the form of heat or light, atoms can be forced to form molecules. Sometimes, this process happens because of a natural process. Hydrogen gas is a molecule of two atoms of elemental hydrogen combined. A hydrogen atom consists of a single proton with a single electron bound to the proton by what is know as coulomb force, basically a positive particle attracting a negative particle in a love relation. When two of these atomic lovers come together, they form a marriage of sorts, a covalent bond that unites them together to share their electrons and become a pair of atoms that we call a molecule. How lovely! The quantum physicists call this a wavefunction. Whatever!
This sharing of electrons in a marriage arrangement is called chemical bonding, but these marriages are not necessarily monogamous. A single atom can form bonds with several other atoms to form complicated molecules such as proteins, the kind of stuff we’re made out of. A carbon atom, for example, can form bonds with four other atoms. Methane is a molecule that consists of one atom of carbon bonded with four hydrogen atoms, definitely a polygamist arrangement.
A protein is a large molecule or macromolecule made from long chains of amino acid molecules. The creation process to make proteins takes place in the cell using DNA, and it’s sister RNA, to form specific proteins. It’s what makes life possible. Amino acids are compounds (stable molecules) that contain an amine group (a nitrogen atom connected to two hydrogen atoms) and a carboxylic acid group (a carbon atom connected to an oxygen atom via a double bond (sharing more than one pair of electrons) and a hydroxyl group (an oxygen atom combined with a hydrogen atom). These amino acids, some of which contain sulfur, are connected together in a stereo-specific sequence as a long chain molecule that can be bent and twisted into all sorts of shapes.
There are nine essential and thirteen nonessential amino acids. The length, composition and physical properties of a particular protein depend upon the precise assembly of specific amino acids by RNA in a cell. Our bodies are composed of trillions of these cells where the stuff of life is made.
Chemical bonding is mostly an electrostatic attraction, sort of like a sexual attraction, between opposite charges. There are strong bonds, such as covalent or ionic, that are hard to break like arranging a difficult divorce. In other words, it takes lots of energy to break them up. In essence, a strong bond is when the atomic nuclei share electrons in order to stay connected. This is much like a married couple sharing a domicile and assets to stay together.
There are weaker bonding types, like dipole interactions, or hydrogen bonding, mostly weak electrostatic forces that form to make stuff stick together. For example, water molecules are hydrogen bonded to make them stick together to not only resist boiling but also allow for freezing. Fortunately for us, proteins are formed with amino acid molecules connected by strong bonds.
All of these wondrous protein-forming events take place to make us possible. Thank goodness.
Thanks for reading.