Topic 5 What is MATTER ? Early Ideas

Topic 5What is MATTER? Early Ideas

Dr. Donna BrestenskySBU Chemistry Department

Acknowledgments:J. Benington, for course text and some slides

J. Miller, for some slides and pictures

Lecture Questions• How do study of motion and study of matter compare?

• What ideas make up modern view of matter?

• What types of matter were ancient people aware of?

• What were Greek philosophers’ ideas about matter?

• What were the significant historical chapters in humans’ study of the nature of matter?

– Alchemists– Scientific Revolution– Chemical Revolution

How do study of motion and study of matter compare?

• Newton’s theory of universal gravitation– A major triumph of early science– Gravity: a universal property of all matter– Strength of attraction a simple function of mass,

regardless of material– Whatever planets are made of, they have mass!

• What about properties that distinguish one type of matter from others?

What ideas make up our modern view of matter?

Dr. Leah Frye, medicinal chemist at Schrodinger

A Classification of Matter: Phases

• Bottle A:GAS

• Bottle B:LIQUID

• Bottle C:SOLID

A Classification Scheme for Matter

MATTER

Pure Substances Mixtures

Homogeneous Mixtures

Heterogeneous Mixtures

CompoundsElements

“The Basics”:How Do We Understand Matter?

• Everything is made of atoms.• Atoms are made of protons, neutrons, and electrons. • Atoms are not all the same: each element has a

different number of protons.• Atoms share electrons to form molecules.• Chemical reactions rearrange atoms in molecules.

(from Benington’s text)

Atoms are Made of Protons, Neutrons, and Electrons.

An atom is really, really, really small!

Trillions onspeck of dust!

Atoms are not all the same.

• If atoms differ, they represent different elements.

• Each element has a different and unique number of protons.

• Usually, # of protons

= # of electrons

• # of neutrons varies.

Atoms Share Electrons

Atoms Share Electrons = Bonds!

Atoms Combine to Form Molecules.

• Molecule = any combination of two or more atoms.

• Most molecules are made of more than one type of atom, but not necessary (can bond 2 of same atom)

• Chemical formula tells how many atoms of each element are in the molecule:– Oxygen is O2

– Water is H2O

– Ammonia is NH3

– Glucose is C6H12O6

What Determines Chemical Properties of Each Element?

• Usually, # of protons = # of electrons

• Electrons tend to fill shells surrounding nucleus

• More open spaces in outer shell more covalent bonds can be made

• Other aspects of atomic structure also relevant

Chemical Reactions Rearrange Bonding of Atoms.

• Number of atoms does not change.– Reactants have same atoms as products

• Only bonding arrangement of atoms changes.– Different molecules after reaction

• Methane + oxygen gas carbon dioxide + water– CH4 + 2 O2 CO2 + 2 H2O– One carbon, four oxygen, four hydrogen

(before & after)

What Types of Matter Were Ancient People Aware of?

• Stone• Metals• Earths• Salts• Air• Water• Fire

• Woods• Fibers• Seeds• Bones• Flesh• Leather• Pigments

Stone• Limestone

• Marble

• Sandstone

• Shale

• Granite

• Soapstone

Metals• Gold• Silver• Copper• Tin• Iron• Lead• Zinc

Where Do Metals Come From?• Few metals occur naturally in pure form

– Gold, silver, copper deposits found in ancient times

• Most metals occur in ores– Ores look more like earths than like metals

pile ofiron ore

Where Do Metals Come From?• Most metals occur in ores

– Ores look more like earths than like metals– Ores of different metals can be distinguished

lead ore

Where Do Metals Come From?• Most metals occur in ores

– Ores look more like earths than like metals– Ores of different metals can be distinguished– Ores must be processed to yield pure metals– Only a small percentage of metal yielded

copper ore; modern man’s futile attempts at smelting!

Alloys

• Combination of metals

• Better properties– Lower melting point– Stronger, less brittle

• Bronze– Alloy of copper and tin

• Stone age– Stone tool manufacture, no use of metals

• Pre-Copper Age: found gold/silver/copper

• Copper Age (4500 BC): first metal smelted

• Bronze Age (3500 BC): strong copper/tin alloy– can be sharpened, easily worked– copper and tin deposits only in certain places

• Iron Age (1500 BC on): – requires very hot furnace, hard to work– iron is found all over the Earth

Metal Working in Cultural Eras

Earths

• Clay• Mud• Sand• Silt• Loam• Ash

Pottery

• Fired clay – from 6500 BC?

• Certain clays used– at certain temperature– for certain times

• Patterned, pigmented

Glass

• Melted sand

• Certain sands used• High temperatures• Blown, molded• Earths, metals added color,

strength

Woods

• Sycamore• Willow• Palm• Mulberry• Lotus• Cypress

Fibers

• Grass• Cotton• Flax• Straw• Bulrushes• Hair

Papyrus

Bone and Leather

Arts practiced since early times

In addition to mentioned materials...

• Pigments• Dyes• Perfumes• Fermenting drinks• Tanning

Summary: What types of matter were ancient people aware of?

• Ancient peoples distinguished many different materials.

• Engineers and artisans had developed many materials technologies.

• These technologies were applied knowingly to specific materials for specific purposes.

What were Greek philosophers’ ideas about matter?

• Thales• Anaximenes• Heraclitus

• Empedocles• Aristotle

• The early “Atomists”: Leucippus, Democritus

Nature of substances: basic element?Thales (640–546 BC)

• Basic element is water.

• In greatest quantities

• Found as solid, liquid, and gas

Anaximenes(570 BC)

• All space above Earth is air.• Air must be element of universe.• Compress it to form harder, denser water and Earth?

Heraclitus(540-475 BC)

• Change = Earth characteristic• Basic element must be changeable.• Fire must be that element.

Empedocles – Four Elements(490 – 430 B.C.)

Noticed burning wood...

• fire issues from it

• water oozes from it/hisses

• air (smoke) is produced from it

• earth (ashes) remain behind

Four Elements Theory of Ancient Greeks(Empedocles/Aristotle)

• Theory had a few main principles (incl. natural motion)

• Elements contained certain mixtures of Four Qualities:Dry vs. Moist, Hot vs. Cold

Changing one element into another?• Changing proportions of qualities = changing one Element into another.

• Elements themselves seem to be interchangeable: Water air when it evaporates Air water when it rains

• Possible for one Earth-y substance to change into another? Idea carries over into alchemy: transmutation?

Leucippus and Democritus (400? BC)

• Greek philosopher and his “student”

• New idea: - there is a limit to how far matter can be divided- atomos: “uncuttable” particles,

different shape/size

Atoms Now and Then…

What were the most significant chapters in humans’ study of the

nature of matter?

• Alchemy• Scientific Revolution• Chemical Revolution

Alchemy

• Greek-influenced alchemy• Chinese alchemy• Arab/Islamic alchemy

• Arab traditions passed to medieval Europeans

• Paracelsus• Iatrochemists

Greek-influenced Alchemy(300 BC – 650 AD)

Two branches:

• Esoteric: religious/astrological, attempt to understand god/gods and find salvation.

• Exoteric: worldly/magical, wealth-focused- Related to Four Elements/Qualities: search

for the “Philosopher’s Stone” to change (transmute) base metals to gold

- Sulfur and mercury were magical

Eastern/Chinese Alchemy

• Independent of (and prior to?) Western alchemy

• Chinese believed there were Five Elements: Fire, Water, Three Solids (Earth, Wood, Metal)

• Search for the “Elixir of Life,” a potion for eternal life

• Gold is eternal and healing, lead to medical alchemy:soluble “potable gold” is the Elixir (400 BC)

Arab/Islamic Alchemy(approx. 700-1200 AD)

• Used “al-iksurs” (colored “seed” catalysts) in transmutation attempts.

• Stressed experiment (isolate/identify/purify)

• Classified materials based on physical properties as well as origin

• Noted alchemists/scientists: al-Kindi, al-Razi, ibn-Sina (Avicenna), Jabir (Geber)

Ibn-Sina,Avicenna(980-1037)

Islamic physician, poet, scientist, philosopher

Ibn-Sina/Avicenna

• Greatest physician of his time

• Believed in Four Elements, but not transmutation.

• Contributions:- studied dosages and effects of drugs- had idea that chemicals maintain identity

even when combined

Importance of Medicine

• Problems: crowded, unsanitary, infested homes; contaminated food/water; low life expectancy.

• Physicians in medieval Europe had more training/education than average person.

- Most followed ideas of Hippocrates (460- 370 BC) and Galen (129-200 AD).- Disease = imbalance in 4 body humours.

Folk Medicine of The Franciscans

• John of Rupescissa (1320)- alcohol contains “quintessence” for Elixir of Life - Chinese-influenced use of “potable gold”- followers distilled to get purer chemicals and thus found new substances.

• Roger Bacon (1267) - medical alchemist - distillates used as

medicine to fight body corruption.

Paracelsus(Theophrastus

von Hohenheim)

(1493-1541)

Swiss physician,mystic, alchemist

Paracelsus(Theophrastus von Hohenheim)

• Alchemy = study of the cosmos - he chose medicines on basis of astrological connections

• Went against the dominant Galenist medical establishment

• Founded science of iatrochemistry (use of chemical medicines)

Paracelsus’s Idea of Elements

• Modified the sulfur-mercury theory of metals and earth to include the third “Principle” of salt (= inertness).

• Three Elements (Fire, Air, Water) and Three Principles of Earth

• Wood burning: “That which burns is sulfur, that which vaporizes is mercury, and that which turns to ashes is salt.”

Contributions of Paracelsus et al.• Noted that disease spread between persons

(external cause? contrary to Galen’s ideas)

• Wrote book on miners’ diseases caused by mercury/arsenic (environmental medicine)

• Used antibacterials: bismuth/antimony for GI

• Stressed purity and controlled dosage of medicine; looked for one-ingredient “specifics”

• Emphasis on laboratory work influenced next generations of chemists.

Lasting Contributions of Alchemy• Laboratory equipment• Chemical techniques• New chemical reactions• New substances

The Scientific Revolution:era of rediscovery, waves of change

Early chemists of the 1600s• Van Helmont (left)• Boyle

* They didn’t believe in “Three Principles.”

The Chemical Revolution:exciting new discoveries,

new ideas bear fruit

Key chemists of the 1700s: studied “airs”• Black• Cavendish• Priestley• Lavoisier

(Black) (Priestley; Lavoisier, w/ wife Marie)

REMINDER:

Exam #1

Friday, October 1

in Individual Classrooms

Try not to be late!