Introduction: Measurement, Mathematical Operations; Introduction to Chemistry Topic 1

Measurement Measurement, from the Greek word "metron", meaning limited proportion is the estimation of the magnitude of some attribute of an object, such as its length or weight, relative to a unit of measurement MetrologyMetrology is the scientific study of measurement It involves using a measuring instrument, such as a ruler or scale, which is calibrated to compare the object to some standard, such as a meter or a kilogram

Units of Measurements Imperial system early used as English units then Imperial units came to known as US Customary Units have at times been called foot-pound-second systems Metric System a decimalised system of measurement based on the metre and the gramsystem of measurement metregram it has a single base unit for each physical quantity all other units are powers of ten or multiples of ten of this base unitpowers of ten SI Units Système International d'Unités modern, revised form of the metric systemmetric system two types of SI units, Base and Derived Units

SI Base Units NameSymbolQuantity metre m Length Kilogram kg mass second s time ampere A electric current electric current kelvin K thermodynamic temperature thermodynamic temperature mole mol amount of substance amount of substance candela cd luminous intensity luminous intensity

SI Prefixes yotta,(Y), meaning deci,(d), meaning zetta,(Z), meaning centi,(c), meaning exa,(E), meaning milli,(m), meaning peta,(P), meaning micro,(u), meaning tera,(T), meaning nano,(n), meaning giga,(G), meaning 10 9 pico,(p), meaning mega,(M), meaning 10 6 femto,(f), meaning kilo,(k), meaning 10 3 atto,(a), meaning hecto,(h), meaning 10 2 zepto,(z), meaning deka,(da), meaning 10 1 yocto,(y), meaning

Instruments used for measuring

Example Convert the following measurements: L = _____ cc 2. 25°F = _____ °K mg = _____ kg hrs = ______ s 5. 1 x mol = ______ mol

Example Convert the following measurements: (Answer) L = 34, 000cc 2. 25°F = °K mg = kg hrs = s 5. 1 x mol = 0.01 mmol

Basic Mathematical Operations MDAS rule Perform multiplication/division first before addition and subtraction e.g. Solve the following: 1. 32(6+5) – 4/2 + (35+8) 2. {3[4+8]/6} – (2+5(6)-12)

Basic Mathematical Operations MDAS rule Perform multiplication/division first before addition and subtraction e.g. Solve the following: 1. 32(6+5) – 4/2 + (35+8) = {3[4+8]/6} – (2+5(6)-12) = -14

Rounding-off Figures Rule 1: If the digit after that being retained is LESS than 5, the retained digit is unchanged. Rule 2: If the digit after that being retained is GREATER than 5, the retained digit is increased by one. Rule 3: f the digit after that being retained is EQUAL to 5, what follows determines how to round the number. If even number, retained If odd number, increase by 1

Example Round to the nearest hundredths: = _____ = _____ = _____ = _____ = _____

Example Round to the nearest hundredths: (Answer) = = = = = 2.34

Significant Figures Guidelines for Using Significant Figures 1. Any digit that is not zero is significant. 2. Zeros between nonzero digits are significant. 3. Zeros to the left of nonzero digit are not significant. 4. If a number is greater than 1, all zeros written after the decimal point is significant. 5. If a number is less than 1, zeros before the nonzero digit is not significant. 6. For numbers that do not contain decimal point, the trailing zeros (zero after the nonzero digit) may or may not be significant. 7. In addition and subtraction, the number of significant figures in the answer is determined by the digit that has the least number of decimal places. 8. In multiplication and division, the number of significant figures in the product or quotient is determined by the original number that has the least number of significant figures.

Significant Figures Example: , x

Significant Figures Example: = = ,100 = x 10 3 = = 4

Significant Figures Example: 1. 12, x / 1.3

Significant Figures Example: 1. 12, = x = / 1.3 = 1.2 x 10 -2

Scientific Notation In observance of significant figures, scientist used scientific notation to express extremely large or small numerical values. All can be expressed in the form: N x 10 n

Step 1: Find n Step2: Count the number of places that the decimal point must be moved to give the number N. Step 3: If the decimal point has to be moved to the left, n is a positive integer or to the right, n is a negative integer Scientific Notation

Example: Scientific Notation

Example: = x = x = 9.2 x Scientific Notation

Accuracy and Precision Accuracy determines how close a measurement is to the true value of the quantity that is being measured. Precision refers to the closeness of two or more measurements of the same quantity with one another.

Error Error refers to a difference between actual behavior or measurement and the norms or expectations for the behavior or measurement norms Two types: 1. Systematic Error (determinate) 2. Random Error (indeterminate)

Error

Chemistry History began with the discovery of fire leads to the purification of metals (metallurgy)alchemy

Alchemy Mission:protoscience to discover the elixir of life (fountain of youth) to create gold through transformation

Alchemy Failure: no scientific method unable to established nomenclature unable to reproduce experiments

Timeline First chemists – the Moslems Geber – the father of chemistry Robert Boyle – alchemist turned chemist differentiate alchemy and chemistry Antoine Lavoisier

Timeline Aristotle“atomos” John Dalton J. J. Thomson Ernest Rutherford

Timeline Chadwick Niels Bohr E. Schrodinger Dmitriv Mendeleyeev

Inorganic chemistry is the study of the properties and reactions of inorganic compounds. Organic chemistry is the study of the structure, properties, composition, mechanisms, and reactions of organic compounds. In other words, it is the study of those substances that contain carbon. Divisions of Chemistry

Analytical chemistry is the analysis of material samples to gain an understanding of their chemical composition and structure. Analytical chemistry incorporates standardized experimental methods in chemistry. Biochemistry is the study of the chemicals, chemical reactions and chemical interactions that take place in living organisms. Physical chemistry is the study of the physical basis of chemical systems and processes. In particular, the energetics and dynamics of such systems and processes are of interest to physical chemists.

Other subdivisions: Astrochemistry Atmospheric chemistry Chemical Engineering Chemo-informatics Electrochemistry Environmental chemistry Geochemistry Green chemistry History of chemistry Materials science Medicinal chemistry Molecular Biology Molecular genetics Nanotechnology Organometallic chemistryPetrochemistry Pharmacology Photochemistry Phytochemistry Polymer chemistry Supramolecular chemistrySurface chemistry ThermochemistryTheoretical Chemistry Nuclear Chemistry Divisions of Chemistry