earth water air fire The early Greeks believed these four forms of matter made everything in the world The ancient Greeks didn’t have access to the knowledge people have today The problem with Empedocles’s ideas was after breaking a stone the pieces never looked like any of the four basic elements Still his idea was important to science because he was the first to state that some materials were made of a combination of things called elements 6
Later another Greek Democritus proposed a new theory He reasoned that by cutting stone into smaller and smaller pieces that it would finally produce a tiny piece of matter he called the atomos meaning indivisible The atomos of the stone were formed of the same matter The stone atomos differed from atomos of other matter such as rabbit fur This theory established the idea that matter was made of different kinds of things Democritus 460 370 BCE Democritis thought atoms were different in shape and appearance and that they were all different sizes with many variations
Aristotle 384 322 BCE embraced Empedocles’s theory He added his own idea that the four main elements could be changed into any of the other Aristotle held great influence at the time The ideas of Democritus were ignored for about 2,000 years Between the 1600s and 1700s new theories contributed to the knowledge of matter In 1643 Evangelista Torricelli an Italian mathematician demonstrated that air had weight by developing the barometer which exerted a force on mercury a liquid metal Plato 428 427 348 347 BCE Aristotle and Plato famous Greek philosophers living at this time disagreed with the ideas of Democritus Aristotle 8 Evangelista Torricelli 1608 1647
Lighter than Air A barometer is an upside down glass tube standing in mercury When air pressure pushes down on the surface of the mercury it makes some of the liquid metal rise up the tube The more air pressure the higher the mercury rises Joseph Priestley 1733 1804 Joseph Priestley a philosopher and chemist experimented with stones containing mercury Priestley noticed that heating the stone produced a gas in addition to the mercury He studied the gas which at the time he called dephlogisticated air and concluded that substances combine or break apart to create new different substances As a Matter of Fact The air around us is made of a mixture of many gases including nitrogen and oxygen 9 vacuum tube Glass 760 mm 29.92 in Atmospheric pressure Mercury In the 1720s Daniel Bernoulli a Swiss mathematician suggested that gases such as those in the air were formed of tiny particles so small they couldn’t see or feel them These particles spread out and were loosely packed in an area of space moving when people walked through them
