2. UNIT 1
FUNDAMENTAL CONCEPTS IN CHEMISTRY
INTRODUCTION
Chemical principles are important in diverse areas, such as:
*Environmental issues like global warming, management of the
Green House gases, ozone layer depletion, acid rain, etc
*Chemical industries manufacturing alkalis, acids, salts, dyes,
polymers, soaps, detergents, metals, alloys
*Drugs to fight disease taxol, are effective in cancer therapy and
AZT (Azidothymidine) used for helping AIDS victims
*Understanding of bio-chemical processes, use of enzymes for
large-scale production of chemicals
*Agrochemicals like fertilizers, pesticides, herbicides
*Fuel for transportation such as diesel, petrol
*Construction industry cement, plastics
07/18/2022
Grade 11 Chemistry Unit 1 2
3. THE SCOPE OF CHEMISTRY
Chemistry
- deals with the composition, structure and properties of
matter.
- is called the science of atoms and molecules.
- the science of matter and its transformation
- often intertwined with branches of science like Physics,
Biology, Geology etc
07/18/2022
Grade 11 Chemistry Unit 1 3
4. Changes that a matter undergoes are broadly classified into
chemical and physical changes.
Chemical changes/chemical reactions
~Results in the formation of new chemical substances
~Involves making/combination or breaking/dissociation of
bonds between atoms
~Are difficult to reverse
~Accompanied by heat changes
~Examples iron rusting, burning, bread rising/fermentation,
milk souring, and sun tanning…
07/18/2022
Grade 11 Chemistry Unit 1 4
5. Physical changes
~Rearrange molecules but do not change their identities
~Each retains their composition
~Mostly accompanied by changes in physical state
~Involves separating mixtures
~Are easily reversible
~Small or no heat change
~Examples magnetizing, melting of solids and boiling of
liquids, dissolving, dicing potatoes…
07/18/2022
Grade 11 Chemistry Unit 1 5
6. There are two kinds of physical properties, namely,
extensive and intensive physical properties.
Extensive physical properties
~Depend on the amount or quantity of sample
~Can vary from sample to sample
~Are additive for subsystems
~Mass, amount of substance, entropy, volume, energy,
length, elec. Resistance,
07/18/2022
Grade 11 Chemistry Unit 1 6
7. Intensive physical properties
~Independent of the amount of substance
~Do not vary from sample to sample
~ are useful in distinguishing between different substances
~Density, color, concentration, melting point, hardness,
pressure, temperature, specific gravity
07/18/2022
Grade 11 Chemistry Unit 1 7
8. Major fields of chemistry
There are several branches of chemistry, let’s start by taking
a look at the 5 main branches of chemistry
Inorganic chemistry
-focuses on elements and compounds other than carbon and
its compounds
-It largely concerns itself with the study of minerals found
in the Earth's crust such as oxides, sulfides, carbonates
Organic chemistry
-is the chemistry of compounds that consists primarily of C
and H except carbides, CO2, CO, carbonates, and hydrogen
carbonates.
-the major nutrients in the food comprises of organic
compounds
07/18/2022
Grade 11 Chemistry Unit 1 8
9. Physical chemistry
-is the study of physical properties of materials like
thermal, electrical, and magnetic behavior
-thermodynamics, spectroscopy, quantum chemistry,
chemical kinetics, and electrochemistry are subdivisions of
physical chemistry.
Analytical chemistry
-involves the qualitative and quantitative determination of
the chemical components of substances
Biochemistry
-This branch deals with the chemical changes going on in
the bodies of living organisms; plants and animals.
07/18/2022
Grade 11 Chemistry Unit 1 9
10. MEASURMENTS AND UNITS IN CHEMISTRY
A measured quantity is usually written as a number with an
appropriate unit.
SI units
To express the measurement of any physical quantity two
things are considered:
(i) Its unit, (ii) The numerical value.
07/18/2022
Grade 11 Chemistry Unit 1 10
12. Mass
~is the amount of matter contained in an object.
~measured with an analytical balance
~is not affected by gravity
Length
To measure length
~In the laboratory, cm and mm
~On the microscopic scale, µm, nm, etc are used
Time
~Short time intervals are expressed through ms, µs, ns, ps.
~Long time intervals usually expressed in non-SI units:
min, h, d, and yr.
07/18/2022
Grade 11 Chemistry Unit 1 12
13. Temperature
~is the measure of the average energy of motion or KE of a
particle.
~is measured by thermometer
~tells us in what direction heat flows
common scales
07/18/2022
Grade 11 Chemistry Unit 1 13
15. The Kelvin scale assigns 0K (-273.150C) to the lowest
possible temperature, which is called absolute zero. This
temperature is a hypothetical temperature by complete
absence of thermal (kinetic) energy.
Mole(amount of substance)
A mole of a substance represents 6.023 x 1023 particles (NA)
07/18/2022
Grade 11 Chemistry Unit 1 15
16. Derived SI units
Force
~F=ma
~The SI unit of force is Newton
~1N=1kgm/s2
Density
~ρ=m/V
~measured in units of gcm-3, kgm-3, g/mL
~is always measured at specific temperatures
07/18/2022
Grade 11 Chemistry Unit 1 16
17. Volume
~is the space occupied by a solid, liquid or gas.
~The volume of a liquid can be measured by graduated
cylinder, a burette, or a pipette.
~The SI unit of volume is liter (L)
1L=1dm3=1000cm3=1000mL
07/18/2022
Grade 11 Chemistry Unit 1 17
18. Pressure
~P=F/A
~The SI unit of pressure is Pascal (Pa)
~1Pa= 1Nm-2
~non-SI units
1 atm = 760 mmHg = 760 torr = 101.3 kPa
Concentration
~is the amount of solute present in a given quantity of
solvent or solution
~is expressed in molarity, molality and mole fraction
07/18/2022
Grade 11 Chemistry Unit 1 18
20. Dimensional Analysis
Often while calculating, there is a need to convert units
from one system to other.
07/18/2022
Grade 11 Chemistry Unit 1 20
21. Uncertainty in measurements
In scientific work, we recognize two kinds of numbers:
exact numbers and inexact numbers.
Exact numbers are those that have defined values/known
exactly. E.g. 1m =100cm
Example there is exactly 1000m in a km.
Numbers obtained by measurement are always inexact.
The last digit in a scientific measurement is usually
regarded as uncertain.
07/18/2022
Grade 11 Chemistry Unit 1 21
22. Seeing that the liquid is between the 25 °C and
30 °C marks, we estimate the temperature to be
27 °C, being uncertain
of the second digit of
our measurement.
07/18/2022
Grade 11 Chemistry Unit 1 22
23. Measurements made with ruler A will have greater
uncertainty than those made with ruler B.
07/18/2022
Grade 11 Chemistry Unit 1 23
24. Measurement = (best estimate ± uncertainty) units
All measurements have some degree of uncertainty that
may come from a variety of sources.
Common sources of uncertainty are usually
~The person doing the measurement (carelessness, poor
technique, bias, zero offset)
~Measuring device
~Environmental factors
~Variability in the item being measured
07/18/2022
Grade 11 Chemistry Unit 1 24
25. Precision and accuracy in measurements
Precision and accuracy are terms used to express
uncertainty in measurement.
Precision
indicates how closely repeated measurements match each
other.
- is the degree of consistency and agreement among
independent measurements of the same quantity
- is good if each measurement is close to the average value
- is about the reliability or reproducibility of the result.
More precise has the smallest uncertainty
⇒
07/18/2022
Grade 11 Chemistry Unit 1 25
26. Accuracy is the closeness of agreement between a
measured value and a true or accepted value.
More accurate closer to the true value
⇒
Precision and accuracy are linked with two common types
of errors called random and systematic errors.
07/18/2022
Grade 11 Chemistry Unit 1 26
27. Random errors
~Makes a measurement less precise but not in any particular
direction
~Arise mostly from limitations of instrument or a person
~Are in either direction
~Can be minimized by performing multiple measurements
~A result is said to be precise if the random error is small
~Affects mainly the precision of the result
Systematic errors
~Always affects a result in a particular direction, and skews
accuracy in that direction
~Arise from incorrectly calibrated instrument and personal errors
~A result is said to be accurate if it is relatively free from
systematic error
~Affects mainly the accuracy
07/18/2022
Grade 11 Chemistry Unit 1 27
28. Rounding off numerical results (retention of sig. figs)
If the digit involved is less than 5, it is neglected and the
preceding significant figure remains unchanged,
4.312 is rounded off to 4.31.
If the digit coming after the desired number of significant
figures happens to be more than 5, the preceding
significant figure is increased by one.
4.317 is rounded off to 4.32.
07/18/2022
Grade 11 Chemistry Unit 1 28
29. Rounding off numerical results (retention of sig. figs)
If the digit happens to be 5, the last mentioned or preceding
significant figure is increased by one only in case it
happens to be odd. In case of even figure, the preceding
digit remains unchanged.
8.375 is rounded off to 8.38 while 8.365 is rounded off to
8.36.
Note that if 5 is followed by non-zeros, the final digit is
increased by 1.
7.5613 rounds to 7.6.
Round the following number to 1,2,3,4 and 5 sig. figs.
5726.302 ans. 6000,5700,5730,5726,5726.3
07/18/2022
Grade 11 Chemistry Unit 1 29
30. Significant figures
~are meaningful digits in a measured quantity.
~ All digits known with certainty, plus one of uncertain value
~correctly indicate the precision of a measurement
There are certain rules for determining the number of
significant figures. These are stated below:
(1) All non-zero digits are always significant.
For example in 285 cm, there are three significant figures.
(2) Leading zeros in a number are not significant. Such zero
indicates the position of decimal point. Thus, 0.03 has one
significant figure and 0.0052 has two significant figures.
(3) Captive zeros are significant.
Example 2.005 has four significant figures.
07/18/2022
Grade 11 Chemistry Unit 1 30
31. (4) If a number has a decimal point, trailing zeros are
significant.
For example, 0.200 g has three significant figures.
But, if a number has no decimal point, trailing zeros are not
significant.
For example, 100 has only one significant figure, but 100.
has three significant figures and 100.0 has four significant
figures.
Such numbers are better represented in scientific notation.
We can express the number 100 as 1×102 for one
significant figure, 1.0×10 2 for two significant figures and
1.00×102 for three significant figures.
07/18/2022
Grade 11 Chemistry Unit 1 31
32. Scientific notation
Scientific notation is
A way of expressing large or small numbers as factors of
the powers of 10.
Exponential notation in which any number can be
represented in the form a × 10b where b is an exponent
having positive or negative values and a is a number
(called digit term) which varies between 1 and 10.
1≤a<10
Example, 0.000105 = 1.05 x 10-4
07/18/2022
Grade 11 Chemistry Unit 1 32
33. Follow the following rules for proper answers of
operations of numerical values
Addition and Subtraction of Significant Figures
~the result cannot have more digits to the right of the
decimal point than either of the original numbers.
4.231 + 3.51 ans. 7.74
2.36 + 5.4 7.8
420 + 3.51 424
300 – 47.465 300
5.4x 103 + 2.1 x 104 2.6x 104
07/18/2022
Grade 11 Chemistry Unit 1 33
34. Multiplication and Division of Significant Figures
~in these operations, the result must be reported with no
more significant figures as are there in the measurement
with the few significant figures.
@answer the following
8.4 x 5 ans. 40
3.46 x 2.1 7.3
9.365 x 14.315 134.1
32.6 ÷ 2.8 12
07/18/2022
Grade 11 Chemistry Unit 1 34
35. CHEMISTRY AS EXPERIMENTAL SCIENCE
The scientific method
The scientific method consists of unique techniques for
investigating phenomena, acquiring new knowledge, or
correcting and integrating previous knowledge.
07/18/2022
Grade 11 Chemistry Unit 1 35
37. Scientific law- is a concise verbal statement or a mathematical equation
that summarizes a broad variety of observations and experience.
Hypothesis
~ is a tentative explanation of a law
~is useful if it can be used to make predictions that can be tested and
verified by experiments
~is an idea that has not been proven yet
Theory
is an interpretation
a possible explanation of why nature behaves in a particular way
is a hypothesis that have been supported with repeated testing
Hypotheses that survive many experimental tests
Just like hypothesis, theories can be proven or rejected
A natural law is a summary of observed (measurable) behavior,
whereas a theory is an explanation of behavior. A law summarizes what
happens; a theory (model) is an attempt to explain why it happens.
07/18/2022
Grade 11 Chemistry Unit 1 37
38. Chemistry laboratory Apparatus
On the basis of their use, chemical apparatus can be
broadly classified into three categories:
~Reaction vessels, e.g., beakers, flasks, test tubes
~Measuring equipments, e.g., pipettes, burettes, balances,
thermometers
~Support and heating devices, e.g., stand and clamp, tripod
and gauze, spirit burner and Bunsen burner
Chemistry laboratory safety rules(reading assignment)
07/18/2022
Grade 11 Chemistry Unit 1 38
39. Writing a laboratory report
A laboratory report
~Is a written composition of the results of an experiment
~Should be written precisely and clearly
Each report must include
~Title
~Objective
~Chemicals and materials used
~Procedure
~Data/observations
~Result and discussion
~Conclusion
07/18/2022
Grade 11 Chemistry Unit 1 39
40. EUEE Chemistry Ginbot 2010
1. What is the sum of 3.71x108 and 4.62x107 to the correct
significant figure?
(A) 4.991x107 (C) 4.17x108
(B) 4.99 x 107 (D) 4.172x108
2. What is a measure of the closeness of a measurement to
its true value?
(A) Precision (C) Reproducibilty
(B) Usefulness (D) Accuracy
3. What skill is a scientist using when he/she listens to the
sounds that animals make?
(A) making observations (C) drawing conclusions
(B) making a hypothesis (D) interpreting data
07/18/2022
Grade 11 Chemistry Unit 1 40
41. 4. The relationship between picometer (pm) and
nanometer(nm) is
(A) 1 pm = 10 nm (C) 1nm = 1000 pm
(B) 1 nm = 10 pm (D) 1 pm = 100 nm
5. To determine the volume of an irregularly shaped glass
vessel, the vessel is weighed empty(121.3 g) and when
filled with CCl4 (283.2 g). What is the volume capacity of
the vessel, given that the density of CCl4 is 1.59 g/cm3?
(A) 101.82 cm3 (C) 178.11 cm3
(B) 76.29 cm3 (D) 257.42 cm3
07/18/2022
Grade 11 Chemistry Unit 1 41
42. EUEE Chemistry Ginbot 2011 Unit 1
1. Precision refers to________
(A) how close a measured number is to the true value
(B) how close a measured number is to zero
(C) how close a measured number is to other measured numbers
(D) how close a measured number is to the calculated value
2. What is the basis for the Scientific Method?
(A)To formulate a research problem, test the hypothesis under
carefully controlled conditions that challenge the hypothesis
(B) To test hypotheses and if they are disproved, they should be
abandoned completely.
(C) To test hypotheses in conditions that are favorable to their
success.
(D)To formulate a research problem and disprove the hypothesis.
07/18/2022
Grade 11 Chemistry Unit 1 42
43. 3. What is the first step in a scientific investigation?
(A) Ask questions (C) Do research
(B) Make observations (D) Draw conclusions
4. Which of the following is the SI measurement unit of
electric current?
(A) Ampere (C)Volt
(B) (B) Watt (D)Coulomb
07/18/2022
Grade 11 Chemistry Unit 1 43
5. Which of the following has the same number of
significant figures as the number 1.00310
(A) 100 (B) 1x 106
(C)199.791 (D)5.119
