Tro Nivaldo - 30-Second Chemistry

Chemistry helps us understand that we - and all things around us - are made up of particles.

Once the particulate model was accepted in the 1800s, progress came relatively quickly. Scientists began figuring out the structure of the basic particles that compose matter, and by the early-to-mid twentieth century, chemists had good models that explained how atoms bond together to form molecules, and how the structures of atoms and molecules affect the properties of the substances they compose. In fact, throughout chemistry, the relationship between structure and properties is a key unifying theme.

A second unifying theme of chemistry is the progression from simple to complex. It turns out that, in nature, when you put together simple particles in slightly different ways, you can get vast complexity. Just as the 26 letters of our alphabet can be combined in different ways to compose many words, and just as you can combine those words in many ways to form an even larger number of complex ideas, so the 91 elements that compose matter can be combined to form many compounds, and those compounds can be combined to form an even larger number of complex substances, including all living things.

How far can chemistry go in its explanations? We still dont really know. We know that chemistry can explain how a gas behaves, but can it explain how a human brain behaves? The second half of the twentieth century saw the outgrowth of chemistry into biology with tremendous success. We now know details about the structures of the complex molecules at the core of life, and how those structures affect many attributes of living things. We have been able to custom-make molecules to fight disease, and even change the hereditary molecules (DNA) in living organisms to alter the characteristics of those living organisms. The twenty-first century has brought new challenges and new directions. On one frontier, scientists are using the ideas in chemistry to try to explain even more complex phenomena, such as human consciousness, for example. On another frontier, scientists are using chemistry to build ever smaller structures and machines, one atom at a time. Someday we may have molecular submarines, capable of navigating the bloodstream to fight invading cancer cells or viruses. On yet another frontier, scientists have created new materials such as graphene, a two-dimensional substance only one atom thick and stronger than steel. It seems that, at least for the foreseeable future, the power of the particulate model of matter to explain behaviour and produce new technology will continue.

Graphene is a new, carbon-based material that is just one atom thick but is stronger than steel.

A tour of this book

In this book, we present the 50 most important ideas in chemistry. Each entry is broken up into several parts: the 30-second chemistry is the body of the explanation; the 3-second nucleus is the idea expressed in a single sentence; the 3-minute valence describes how the idea fits within a wider context, or can be applied to different circumstances. The book starts with atoms, their structures and their properties. It then goes on to show how atoms bond together to form compounds, and how we can understand bonding and the resulting molecules. From there we move on to the states of matter (gases, liquids and solids) and then on to chemical reactions. We then examine the energetics and describe the laws that govern the flow of energy. Finally, we survey four subfields of chemistry: inorganic chemistry, organic chemistry, biochemistry and nuclear chemistry. Our goal throughout is not to provide exhaustive or detailed accounts of chemistry, but rather to give you a flavour of the field to show that behind all that happens around you and inside you, particles are doing a complex and beautiful dance that makes it all possible.

The position of electrons within an atom is central to understanding how atoms bond together.

ATOMS, MOLECULES & COMPOUNDS

ATOMS, MOLECULES & COMPOUNDS
GLOSSARY

alkali metals The column of metals (group IA) on the far left of the periodic table that includes lithium, sodium, potassium, rubidium, cesium and francium.

atomic number The unique number assigned to each element that corresponds to the number of protons in the elements nucleus.

atomic theory The idea that all matter is composed of tiny particles called atoms.

classical physics Physics before the advent of quantum mechanics.

covalent bonding The joining of atoms by the sharing of one or more electrons.

electron A subatomic particle with a negative charge and a mass of 0.00055 amu (atomic mass unit).

element A fundamental substance that cannot be divided into simpler substances. There are 91 naturally occurring elements.

Heisenbergs Uncertainty Principle The quantum mechanical principle that certain quantities, such as position and momentum, cannot be simultaneously specified to arbitrary accuracy.