chemistry 111 ,,,

Chapter 1 Matter; Energy, and Measurement

Medical practice over time' (a) A woman being bled bY a leech on

her left forearm; a bottle of leeches is

on the table, From a 1639 wooilcut' (b) Modern surgery in a well-equipped operating room.

:E

- =

z

E

i

MedicinehasmadegreatStridessincethosetimes.Welivemuchlon- ger, and many or."-[-uiJdi""ur", have been essentially eliminated

or are

curable. Smallpox h;. ;;; erad'icated' and polio' typhus' bubonic plague'

ffi;;#;, and other diseases that once killed millions no longer pose a

;;;;;;;;;ti"-, ut least not in the developed countries' How has this medical progress come about?

The answer is that diseases

could not be cured ""iil tir#*ere understood, and this understanding has

emerged through g"".t"" ft""*f"dge of how the body functions' It is prog-

ress in our underst"ilt"g;?the-f"-irrcipr". of biology, chemistry, and phys-

ics that has led to these Jd"t"t"t in medicine' Because so much of modern

medicinedependsonct,emist,y,itisessentialthatstudentswhointendto enterthehealthprofessionshavesomeunderstandingofbasicchemistry. This book *u" *rit;e-ri to Lrp you achieve that goal. Even

if you choose

a different prof"r.ioi,, y'" *iif"q"d that the chemistry you learn in this

course will greatly enrich your life' Ttre universe consists of matter' energ'y' and

empty space' Matter is any-

thing that has mass and takes op tpu""' Chemistry is the science that

deals with matter: itre ti""t"'" u"d p'op""ties,of rnlltT ""d th: liT: formationsfromoneformofmattertoanother.Wewilldiscussenergyln Section 1.8.

It has long been known that matter can change' or be made to change'

from one form to """tf'"* f" a chemical change' more commonly called

achemicalreaction,substancesareusedup(disappear)andothersare formed to take their places' An example is the

burning of the mixture of

hydrocarbo., orrruly-Ji"a "mttt"a gas." rn this mixture of hydrocarbons,

the main "o*pot "rri

it p"oput'" When this chemical change takes place' propaneandoxygenfromtheairareconvertedtocarbondioxideandwater. itg,rt" 1'1 shows another chemical change'

Matter .fro ,r"a",go; "if'"' fti"at of Jhanges' called physical changes'

These changes diffu;i;;- chemical reactioris in that the identities of the

substances do not;;;;;. M"st physieal changes involve.changes of state-

for example, tfr" ,n"i[irr'g oi.ofla^. and the boiiing of liquids. Water remains

waterwhetheritisintheliquidstateorintheformoficeorsteam.The conversion to- orr" slate to another is a physical-not achemical-change' Another i*port"riffie "i

pt vri"rr chrt ge ln rolves making or separating

*i"t*"r. Dissolving sugu' it' water is a physical change' ' When we talk .U?"t ;he chemical properties.of

a substance' we mean

the chemicut ""u.ti*s that it underlgoes. rnysicat properties-are all

properties tfrat ao ioiinvolve chemiJal reactions. For example, density'

color, melting point, and physical state oiquid, solid, gas) are all physical

properties'

a I =E

, =