Chemistry in a Nutshell
An Introduction to the Atom
Chemistry is the study of the building blocks that make up everything we know and love. Those building blocks are called atoms. To picture an atom, imagine the solar system. Our solar system has a large mass in the middle, the Sun, and the planets revolve around the sun. The sun is so large that it can use its own gravity to hold the planets close to it. Meanwhile, the planets are moving on their own path, called an orbit, around the sun. As they move around the sun, they pull away from the sun's gravity. These two forces balance out so the planets orbit the sun at a set distance. One can compare an atom to the model of the solar system, but with a few tweaks.
In an atom, we have the nucleus and electrons. Everything at this scale works like a magnet. The nucleus is made of positively charged protons, along with uncharged -or neutral- neutrons. The nucleus will represent the sun because it sits in the center of the atom and uses a force to hold the electrons in orbit around it. The nucleus doesn't use gravity, though. Instead, it uses a positive "magnetic" force to hold onto negatively charged electrons. The negative and positive magnetic forces attract just like the north and south end of two magnets. This allows for our electrons to behave like planets in the tiny solar system. The forces once again balance out and they revolve around the nucleus at mind blowing speeds. Speeds so fast that they start to create a shell that protects the nucleus. This shell is what's responsible for reacting with the world around the atom, whether that means interacting with other atoms, light, heat, or magnetic forces.
Making a molecule
When an atom bonds with another atom, the two create a molecule. A molecule is a group of two or more atoms bonded together. There are several ways that they can bond to form molecules. When two atoms begin sharing electrons, they start forming what is called a covalent bond. These bonds can happen because some atoms like pulling electrons away from other atoms. Sometimes an atom can also be very willing to give up an electron. The willingness to give up an electron is called electronegativity. An atom that likes to give up electrons is not very electronegative, While ones that like to hold on to electrons are very electronegative. If an atom that is willing to give up an electron meets one that really likes to take electrons, they will then begin sharing electrons. It is also important to note that electrons can either stand alone or in pairs called lone pairs. When dealing with covalent bonds, we are looking at the single electrons interacting with other single electrons.
Molecules can also be formed through ionic bonds. An ionic bond works just like our magnets from earlier. Long story short, there is a positively charged atom, called a cation, and a negatively charged one, called an anion. These two atoms bind together just like the north and south end of a magnet. Now, you may be asking why these are called cations and anions. Well, an ion is a positively or negatively charged atom. The prefix cat- refers to the positive ion. The prefix an- refers to the negative ion. The reason these atoms or molecules can become ions goes back to the number of electrons. An atom consists of one negatively charged electron for every positively charged proton in the nucleus. These magnetic forces cancel out in an atom when it is neutral, or has no charge. If an atom is negatively charged, that means it has more electrons than protons. If it is positively charged, then it has fewer electrons than protons. To bring it all together, an ionic bond occurs when an atom with fewer electrons than protons meets another atom with more electrons than protons. Because of the magnetic difference between the two atoms, they bond with each other and create a salt. Salts are formed when a positive atom from the left side of the periodic table meets a negative atom from the right side of the periodic table and form an ionic bond.
Understanding the Periodic Table
The periodic table is every chemist's best friend. Created in 1869 by Dmitri Mendeleev, It tells you many things about the elements displayed in its boxes. First things first, each element is made of only one specific type of atom. For instance, elemental gold consists of only gold atoms. Elemental carbon consists of only carbon atoms, and so on. Each element has a specific number of protons in its nucleus, starting at one and going up to 118 and possibly beyond (we don't know yet). The number of protons, called the atomic number, defines what element we are looking at. An atom consisting of 14 protons will always be nitrogen, and an atom containing 80 protons will always be mercury. The number in the upper left corner of each box represents the number of protons.
There are two letters in each box. These letters are called the atomic symbol and represent the name of the element: H is hydrogen, C is carbon, and so on. Below the two letters in each box, there is a number called the molar mass. To further understand molar mass, we must first learn what a mole is. A mole, in this case, is not a furry little ground-burrowing animal. In Chemistry, a mole is a unit. By that, I mean a mole represents a specific number of atoms. The number is 6x10^23, also known as 600,000,000,000,000,000,000,000. That number seems massive, right? Well it is, but it isn't. If you tried to think of that many baseballs, your head might start hurting. If we have that many carbon atoms, however, we have a sample of carbon that weighs only 12 grams. Compare that to an egg yolk, which weighs around 18 grams. Hopefully that gives you somewhat of an idea of how small atoms are. The molar mass of an atom is equal to the weight, in grams, of a "mole" of that atom.
Each row in the periodic table is called a period, while each column is called a group. As we go from the first to the last period on the table, our atoms get larger and more energetic. The atoms also get larger as we move from left to right on the table. By a general rule, atoms in the same group tend to behave similarly. Take the noble gases for example. The group to the far right of the periodic table is known a the noble gases. It consists of Helium, Neon, Argon, Krypton, Xenon, Radon, and the newly discovered Oganesson. Most of these elements exist in gas form and tend to keep to themselves. They do not like to react with other elements. This has to do with how these gases all have zero unpaired electrons. Every group has a different number of electrons in its electron shell. That number of electrons determines how the element behaves in the world that You and I can see.
In case you haven't noticed, the table is shaped a little weird. The reason for that are things called orbitals. Orbitals are little "areas" around the nucleus that are designated spots for electrons to live. The table is split up into the four blocks that represent the four types of orbitals: s, p, d, and f. To keep it simple, I will only cover the first three. The s block has the least amount of electrons and therefore has the least amount of energy. It contains the alkali and alkaline earth metals, which are the first two groups of the periodic table (represented in purple on the table above). These elements are very reactive and form cations very easily. Next is the p block. The p block is everything to the right of the blue area on the table above. These elements are important for life and technology. They also can form anions to bond with the first two groups and form salts through ionic bonding. The d block consists of the transition metals. These metals allow electrons to flow relatively freely throughout them, which makes them very good conductors of heat and electricity. Examples of transition metals include iron, lead, copper, gold, silver, etc.
Chemistry may not be for everyone. In the words of my sister, "It's hard to imagine a world that you can't see." Hopefully, that isn't the case for you and I have helped to give you some understanding of the wonderful world of chemistry. If reading this article has peaked your interest and you want to learn more, there are many different areas of chemistry to explore! Organic chemistry is the study of anything and everything carbon related and also involves tracing the movement of electrons in reactions. Biochemistry is the study of the chemical reactions that make life possible. Inorganic chemistry is the study of the transition metals. Quantum mechanics involves studying the behavior of electrons mathematically. Kinetics and thermodynamics are the study of the energy transferred in reactions. Each and every one of these different areas of chemistry is interesting in its own way. The ability to explain the world around you is a wonderful feeling and understanding chemistry will give you the ability to do so.