Ch1 chemistry the study of change

General chemistry 1

1. 1
Chemistry
The Study of Change
Dr. Sa’ibKhouri
AUM-JORDAN
Chemistry
ByRaymond Chang

2. 2
The Study of Chemistry
Macroscopic Microscopic

3. 3
Thescientificmethodisasystematic
approachtoresearch
Ahypothesisisatentativeexplanationfora
setofobservations
testedmodified

4. 4
Atheoryisaunifyingprinciplethatexplainsa
bodyoffactsand/orthoselawsthatarebasedon
them.
Alawisaconcisestatementofarelationship
betweenphenomenathatisalwaysthesame
underthesameconditions.
Atomic Theory
Force = mass xacceleration

5. 5

6. 66
Chemistryis the study of matterand the
changes it undergoes
liquid nitrogen gold ingots
silicon crystals
Matterisanythingthatoccupiesspaceand
hasmass(threestates;solid,liquid,andgas)
Asubstanceisaformofmatterthathasa
definitecompositionanddistinctproperties.
Can be defined by their appearance, smell, taste, and other properties.
At present, over 20 million substances are known.

7. 77
A mixtureis a combination of two or more substances in
which the substances retain their distinct identities.
1.Homogenous mixture–composition of the
mixture is the same throughout.
2.Heterogeneous mixture–composition is not
uniform throughout.
soft drink, milk, solder
cement,
iron filings in sand

8. 88
An elementis a substance that cannotbe separated
into simpler substances by chemicalmeans.
•117 elements have been identified
•82 elements occur naturally on Earth
Gold, Aluminum, Lead, Oxygen, Carbon, Sulfur
•35 elements have been created by scientists
Technetium (Tc), Americium (Am), Seaborgium(Sg)

9. 9
Firstletteralwayscapitalized,butsecondisnevercapitalizedSomeelements
arederivedfromtheirlatinnames.E.gAu(aurum),Fe(ferrum),Na(natrium),..

10. 1010
Acompoundisasubstancecomposedofatomsof
twoormoreelementschemicallyunitedinfixed
proportions.
Compoundscanonlybeseparatedintotheirpure
components(elements)bychemicalmeans.
lithium fluoride quartz dry ice –carbon dioxide

11. 1111
A Comparison: The Three States of Matter
Solids: rigid
objects with
definite shapes
Liquids: less
rigid than solid
and are fluid,
they are able to
flow and
assume the
shape of their
containers
Gases: are
fluid but unlike
liquids and
they expand
indefinitely

12. 1212
Aphysicalchangedoesnotalterthecomposition
oridentityofasubstance.
Achemicalchangealtersthecompositionor
identityofthesubstance(s)involved.
ice melting
sugar dissolving
in water
Hydrogen burns in air
to form water
Types of Changes

13. 1313
Anextensivepropertyofamaterialdependsupon
howmuchmatterisbeingconsidered.
Anintensivepropertyofamaterialdoesnot
dependuponhowmuchmatterisbeingconsidered.
•mass
•length
•volume
•density
•temperature
•color
Extensive and Intensive Properties

14. 14
Matter Summary

15. 15
WhatisaMeasurement?
Quantitative observation
that associated with
numbers and units.
The study of chemistry
depends heavily on
measurement.

16. Devices
The meterstick: measures length
The buret, pipet, graduated cylinder, volumetric flask: measure volume
The balance: measures mass
The thermometer: measures temperature
These instruments provide measurements of macroscopicproperties
Microscopicproperties: on the atomic or molecular scale (indirect
method)

17. 17
Units
•Without an associated unit, a measurement
is without meaning.
•SI units (metric units,InternationalSystem).
1960
•In french
Systèmeinternational d'unités

18. 18
The Standard Units
DerivedSIunits
e.g.Area,Volume,Speed,acceleration,
density,Force.

19. Volume (Length)
3
SI: m
3
1 mL = 1 cm
33

20. 20
Related Units in the
SI System
•AllunitsintheSIsystemarerelatedtothe
standardunitbyapowerof10.
•Thepowerof10isindicatedbyaprefix.

21. CommonPrefixesintheSISystem
PrefixSymbol
Decimal
Equivalent
Power of 10
tera T 1,000,000,000,000 Base x 10
12
giga G 1,000,000,000 Base x 10
9
mega- M 1,000,000 Base x 10
6
kilo- k 1,000 Base x 10
3
deci- d 0.1 Base x 10
-1
centi- c 0.01 Base x 10
-2
milli- m 0.001 Base x 10
-3
micro- m 0.000 001 Base x 10
-6
nano- n 0.000 000 001 Base x 10
-9
Pico- p 0.000 000 000 001Base x 10
-12

22. 22
Density
•Inverse relationship between mass and volume.
•Solids = g/cm
3
1 cm
3
= 1 mL
•Liquids = g/mL
•Gases = g/L
•Volumeofasolidcanbedeterminedbywater
displacement—ArchimedesPrinciple.
•Densityofsolids>liquids>gases
Exceptice,itislessdensethanliquidwater!Volume
Mass
Density

25. Temperature Scales
Three Scales
ºF (degree Fahrenheit)
ºC (degree Celsius)
K (kelvin); absolute temperature (SI unit)

27. Scientific Notation
The number of atoms in 12 g of carbon:
602,200,000,000,000,000,000,000
6.022 x 10
23
The mass of a single carbon atom in grams:
0.0000000000000000000000199
1.99 x 10
-23
N x10
n
N is a number
between 1 and 10
nis a positive or
negative integer

28. Scientific Notation
568.762
n > 0
568.762 = 5.68762 x 10
2
Moved to the left by two places
move decimal left
0.00000772
n < 0
0.00000772 = 7.72 x 10
-6
Moved to the right by six places
move decimal right
Addition or Subtraction
1.Write each quantity with
the same exponent n
2.Combine N
1and N
2
3.The exponent, n, remains
the same
4.31 x 10
4
+ 3.9 x 10
3
=
4.31 x 10
4
+ 0.39 x 10
4
=
4.70 x 10
4
2.22 x 10
-2
-4.10 x 10
-3
=
2.22 x 10
-2
-0.41 x 10
-2
=
1.81 x 10
-2

29. Scientific Notation
Multiplication
1.Multiply N
1and N
2
2.Add exponents n
1and n
2
together
(4.0 x 10
-5
) x (7.0 x 10
3
) =
(4.0 x 7.0) x (10
-5+3
) =
28 x 10
-2
=
2.8 x 10
-1
Division
1.Divide N
1and N
2
2.Subtract exponents n
1and n
2
8.5 x 10
4
÷5.0 x 10
9
=
(8.5 ÷5.0) x 10
4-9
=
1.7 x 10
-5

30. pH = 6.855
4 sig. figs
The last digit (5) is
uncertain
i.e. 6.855 ±0.001
Significant Figures
Isthemeaningfuldigitsinameasuredorcalculated
quantity?
Whensignificantfiguresareused,thelastdigitis
understoodtobeuncertain.
pH meter

31. 31
What is the Length?
•We can see the markings between 1.6 -1.7cm
•We can’t see the markings between the 0.6 -0.7
•We must guess between 0.6 & 0 .7
•We record 1.67 cm as our measurement

32. What is the length of the wooden stick?
1) 4.5 cm
2) 4.54 cm
3) 4.547 cm

33. Significant Figures
•Any digit that is not zero is significant
1.234 kg 4significant figures
•Zeros between nonzero digits are significant
606 m 3significant figures
•Zeros to the left of the first nonzero digit are notsignificant
0.08 L 1significant figure
•If a number is greater than 1, then all zeros to the right of the
decimal point are significant
2.0 mg 2significant figures
•If a number is less than 1, then only the zeros that are at the
end and in the middle of the number are significant
0.00420 g 3significant figures

34. How many significant figures are in
each of the following measurements?
24 mL 2 significant figures
3001 g 4 significant figures
0.0320 m
3
3 significant figures
6.4 x 10
4
molecules 2 significant figures
560 kg 2 or 3 significant figures

35. Significant Figures
Addition or Subtraction
The answer cannot have more digits to the right of the decimal
point than any of the original numbers.
89.332
1.1+
90.432 round off to 90.4
one significant figure after decimal point
3.70
-2.9133
0.7867
two significant figures after decimal point
round off to 0.79

36. Significant Figures
Multiplication or Division
The number of significant figures in the result is set by the original
number that has the smallestnumber of significant figures
4.51 x 3.6666 = 16.536366= 16.5
3 sig figs round to
3 sig figs
6.8 ÷112.04 = 0.0606926
2 sig figs round to
2 sig figs
= 0.061

37. Significant Figures
Exact Numbers
Numbers from definitions or numbers of objects are considered
to have an infinite number of significant figures
The average of three measured lengths; 6.64, 6.68 and 6.70?
6.64 + 6.68 + 6.70
3
= 6.67333 = 6.67
Because 3 is an exact number
= 7

38. Accuracy–howcloseameasurementistothetruevalue
Precision–howcloseasetofmeasurements(ofthesame
quantity)aretoeachother
accurate
&
precise
precise
but
notaccurate
notaccurate
&
notprecise

39. Dimensional Analysis Method of Solving Problems
1.Determine which unit conversion factor(s) are needed
2.Carry units through calculation
3.If all units cancel except for the desired unit(s), then the
problem was solved correctly.
given quantity x conversion factor = desired quantity
given unit x = desired unit
desired unit
given unit

40. Dimensional Analysis Method of Solving Problems
Conversion Unit 1 L = 1000 mL
1L
1000 mL
1.63 L x = 1630 mL
1L
1000 mL
1.63 L x = 0.001630
L
2
mL
How many mL are in 1.63 L?

41. Thespeedofsoundinairisabout343m/s.Whatisthis
speedinmilesperhour?
1 mi = 1609 m 1 min = 60 s 1 hour = 60 min
343
m
s
x
1 mi
1609 m
60 s
1 min
x
60 min
1 hour
x = 767
mi
hour
meters to miles
seconds to hours
conversion units