All elements can exist in three different states of matter solid liquid or gas We use room temperature a comfortable temperature of about 70 Fahrenheit 21 Celsius as our consistent point of reference At room temperature the majority of the elements are solid eleven are gas and two are liquid Elements change from one state to another through heating and cooling When an element changes from one state to another the number of atoms remains the same but they arrange themselves in different ways When an element is in solid form atoms are attracted to each other and locked into a tight position Solids keep their shape and have a fixed volume volume is how much space an object takes up While some solids are soft and flexible they are still solid When an element is in liquid form the atoms move around and their attraction loosens Liquids take the shape of the container they are in but their volume remains fixed When an element is in a gas form the atoms are weakly attracted to each other and move in different directions A gas will fill any container no matter how large or small it is States of Matter Solid Liquid Gas 14
Alchemy and Ancient Chemistry Long before the periodic table was developed humans attempted to understand the unique and distinct substances that comprised everything in the known universe What are these essential elements Many ancient cultures like the Babylonians Chinese and Egyptians developed an idea of simple groups wood fire earth metal water and so on The ancient Greeks synthesized the world into just four elements earth water fire and air This theory became elemental to Western thought for 2,000 years The four elements were used to describe not only objects in the seen world but also the temperaments a person might experience and physical sensations in the body called the four humors Maintaining the balance of the four elements humors was thought to be essential not just to the natural world but also to a person’s mental and physical well-being Alchemists and Gold Diggers In the Middle Ages practitioners of alchemy a combination of scientific exploration and mysticism strove to understand the natural world and how to transform it Alchemists were interested in purifying and perfecting metals and sought to change ordinary metals like lead or mercury into gold The material that was thought to accomplish this task was known as the philosopher’s stone Of course no such substance existed but one alchemist Hennig Brand became the first person to chemically discover an element in his pursuit read about the gross idea that led to his discovery of phosphorus on page 43 Air Water Fire Earth The four elements according to the ancient Greeks A Scientific Revolution Building on the efforts and discoveries of the alchemists and riding the wave of new scientific methods pioneering chemists in the sixteenth century began to dismantle the idea of the four elements They discovered that what had been known as elemental earth for example was made up of many components Much of their research involved how different substances that the alchemists had isolated such as arsenic or zinc interacted with each other or other substances such as gases in the air Because some substances behaved similarly under certain circumstances scientists began to classify them into groups in the eighteenth century which was the beginning of the periodic table and our modern understanding of the elements ALCHEMY AND ANCIENT CHEMISTRY 15
Meet Dmitri Mendeleev Organizer of the Elements and Author of the Periodic Table On February 8 1834 in a village in Siberia Russia a baby boy named Dmitri Mendeleev was born That boy would one day change the course of science forever He came from an unusually large family No one knows for sure but he likely had fourteen brothers and sisters When he was thirteen years old his father died and two years later the family’s business burned down In search of a better life his mother took him from Siberia to Saint Petersburg where he gained acceptance to college Despite poor health Mendeleev graduated at the top of his class and after a short stint as a science teacher he returned to Saint Petersburg to continue his education focusing on chemistry 16 ILLUSTRATED ENCYCLOPEDIA OF THE ELEMENTS
A Wild Card Brilliant and eccentric he was known for his long flowing beard and uncut hair Mendeleev poured his passion into a text called The Principles of Chemistry As he worked to explain and to order the elements he saw that atomic weight alone did not present a total picture Inspired by the card game solitaire he made a set of cards one for each element known at the time listing their chemical properties and atomic weight Mendeleev brought these cards with him everywhere he went shuffling and rearranging them Dmitri Mendeleev’s set of cards was based on what scientists knew about the elements at the time Some of the information like the exact atomic mass num bers was wrong but he was still able to arrange the cards to form the periodic table we know today Dream Come True As the story goes in February 1869 Mendeleev became so obsessed with his deck of elements that he stayed awake for three days and nights arranging the cards in different orders eventually falling into a deep sleep at his worktable In a dream all the elements began to dance and then snapped together into a grid Mendeleev awoke with a vision of the periodic table He had finally cracked the code When elements are arranged by their atomic weight certain properties such as whether they are metals or gases reappear periodically hence the name the periodic table of elements In the version of the table he created he left gaps in places where he believed unknown elements would emerge He even predicted the likely properties of potential elements His work has stood the test of time for more than 150 years MEET DMITRI MENDELEEV 17
