CHEM 114_WEEK 1 COMPLETE.pdf

8/30/2024 CHEM 114...

8/30/2024 CHEM 114 WEEK 01 General Chemistry I Instructor: NIÑA JANESSA E. MULLINS ü To recognize the breadth, depth, and scope of chemistry. ü To outline the historical development of Chemistry and Learning recognize its importance in everyday life. ü To identify the components of the scientific method. ü To classify matter, distinguish among elements, compounds, 01. and mixtures, as well as the different types of changes they Objectives undergo. ü To distinguish the different types of energy and their applications. Definition and ü To apply the rules in determining significant figures and use SI units in calculations. ü To explain the dimensional analysis approach to Scope of mathematical calculations involving quantities. ü To define measurement and recognize common measuring tools used in the laboratory. Chemistry ü To identify the properties and units of length, mass, volume, density, temperature, and time. ü To perform basic unit calculations and conversions in the metric and other unit systems. Why Study Chemistry? What is Chemistry? Why Study Chemistry a branch of Science which deals with the study of matter and the Chemistry greatly impacts our daily lives. Indeed, chemistry lies near the heart changes that matter undergoes. It is the study of the composition, structure, Chemistry helps us understand What is Chemistry? of many matters of public concern: improvement of health care, conservation properties, transformation of matter and the energy that is released or of natural resources, protection of the environment, and provision of our daily absorbed during these processes. Chemistry? needs for food, clothing, and shelter. the world around us. By studying chemistry, you will learn to use the powerful language and ideas Chemistry is often called the “Central Science” because of its diverse application. It is essential for understanding much of the natural world and that have evolved to describe and enhance our understanding of matter. central to many other scientific disciplines, including astronomy, geology, Furthermore, an understanding of chemistry provides powerful insights into paleontology, biology, and medicine. other areas of modern science, technology, and engineering. 1  8/30/2024 The Scope of Chemistry The Development of 01. Practical Arts (up to 600 BC) WEEK WEEK 02 WEEK Modern Chemistry 02. Ancient Greece 01 Introduction Atomic Structure of Atom 04 (600 BC to 300 BC) Scope of Chemistry Periodic Table Valency /Oxidation The Scientific Method Electronic Configuration Numbers Matter and Energy Chemical Bonds Measurement Dimensional Analysis 03. Alchemy Significant figures WEEK 03 04. Phlogiston Theory (300 BC to 1650 AD) (“Fire Principle”) Electronic Structure of Atom (1650 to 1790) Quantum Numbers 05. Modern Chemistry (1790-) The Development of Modern Chemistry The Development of Modern Chemistry 1. Practical Arts (up to 600 BC Production of metals from ores, manufacture of pottery, brewing, baking, 3. Alchemy (300 BC to 1650 AD) preparation of dyes and drugs 0 03 0 03 The result of the union of the philosophical tradition of ancient Greece and the The development was based on practical experience alone without reference to craft tradition of ancient Egypt underlying chemical principles. Attempted to transmute cheap metals to gold (with the use of Philosopher’s Stone) Known metals were recorded and listed in conjunction with heavenly bodies. Wanted to enable people to live longer and cure all ailments (Elixir of Life) Was ended by the publishing of the book The Skeptical Chemist by Robert Boyle, 2. Ancient Greece (600 BC to 300 BC) disproving Aristotle’s four elements theory Two important theories: A concept that all substances found on earth are composed of four elements (earth, 4. Phlogiston Theory (“Fire Principle”) (1650 to 1790) air, fire, and water) in various proportions was proposed by Aristotle Was formulated by Johann J. Becher (a German alchemist) in his book Physica A theory that matter consists of separate and distinct units called atoms was Subterranea where he called it “terra pinguis” (renamed to phlogiston by George Ernst proposed by Leucippus and extended later by Democritus Stahl) Plato proposed that the atoms of one element differ in shape from the atoms of Stated that phlogiston, a fire-like element, is contained within combustible things another. So he believed that atoms of one element could be changed (or transmuted) and is released during combustion into atoms of another by changing the shape of the atoms. The Development of Modern Chemistry 02. 5. Modern Chemistry (1790-) Antoine Lavoisier revolutionized Chemistry by performing quantitative experimentation to arrive at his 0 03 explanations of a number of chemical phenomena The law of conservation of mass states that there is no detectable change in mass during the course of a chemical reaction. The Scientific Principal branches: a. Organic Chemistry – the study of carbon (except for few that are classified as inorganic compounds) Method b. Inorganic Chemistry – the study of all the elements except carbon c. Analytical Chemistry – the identification of the composition, both qualitative and quantitative, of substances d. Physical Chemistry – the study of the physical principles that underlie the structure of matter and chemical transformations e. Biochemistry – the study of living systems, both plant and animal. 2  8/30/2024 The Scientific Method The Scientific Method Scientific method is the general approach to solving problems involves The key steps in the scientific method include the following: making observations, confirming that they are reproducible, seeking patterns in the observations, formulating hypotheses to explain the observations, and testing these hypotheses by further experiments. Hypotheses that withstand such tests and prove themselves useful in explaining and predicting behavior become known as theories. It is the process by which scientists acquire systematic and reliable body of knowledge about the world. It is a method of investigation involving experimentation and observation to acquire new knowledge, solve problems, and answer questions. It was first documented by Sir Francis Bacon. The Scientific Method The Scientific Method Step 01. Step 02. Step 03. Step 04. Make an observation. Ask a question. Propose a hypothesis. Make predictions. A hypothesis is a potential answer to A prediction is an outcome we'd the question, one that can somehow expect to see if the hypothesis is be tested. correct. The Scientific Method The Scientific Method Qualitative and Quantitative Observations Step 05. Step 06. Qualitative Observations use your Quantitative Observations are made Test the predictions. Iterate. senses to observe the results. with measuring instruments. Examples: Examples: - Color of a sample -Mass of as sample - Texture of a surface -Length of a piece of - Coarseness of a wire powder -Molecules in a mole - Aroma of a reaction -Volume of a gas - Malleability of a metal -Temperature of a sample To test the hypothesis, we need to make an observation or perform an experiment associated with the prediction. 3  8/30/2024 Matter & Energy Nature of Matter 03. Matter consists of atoms that have protons, neutrons, and electrons. It generally exists in four states e.g. liquid, solid, gaseous, and plasma state. Different kinds of matter have different kinds of atoms. Volume is the amount of space that matter occupies Matter & What is Matter? Matter is anything that occupies space and has All matter have their own density and inertia. mass. Some matter is easy to see (e.g. water, Mass is a measure of quantity of matter and is invariable. wood), others are difficult (e.g. air, dust) A body that is not being acted on by some external force has a tendency Energy to remain at rest or, when it is in motion, to continue in uniform motion in the same direction. This property is known as inertia. Weight is the gravitational force of attraction exerted by the earth on a body and varies with the distance of that body from the center of the earth. Matter & Energy Matter & Energy Classification of Matter How do the molecules of a compound differ from the molecules of an element? On the basis of its chemical composition, matter may be classified as follows: Matter & Energy Matter & Energy Properties of Matter Physical States of Matter Physical Properties Solids Liquids Physical properties are the characteristics of matter that can be changed Solids have definite shape and definite Liquids take the shape of their container and without changing its composition; characteristics that are directly observable; a volume; have mass; take up space; can’t move have definite volume; have mass; take up trait of matter that can be observe without changing the chemical composition from one position to another on their own, however, they can vibrate at room space. of thePhysical matter; noProperties chemical reactions involved. Chemical Properties temperature. Particles in Liquids: Chemical Properties Particles in Solids: ü Are loosely packed Chemical Properties are the characteristics that determine how the ü Are packed tightly together ü Have medium energy levels composition of matter changes as a result of contact with other matter ü Have very little energy ü Particles flow around each other or the influence of energy; A property of matter that describes a ü Vibrate in place after being heated and start substance based on its ability to change into a new substance with moving randomly different properties. Some of these properties are: Flammability / combustibility Ability to react with oxygen Reactivity with acids 4  8/30/2024 Matter & Energy Matter & Energy Physical States of Matter Density Density - the ratio of mass to The Greek letter “Rho” (ρ) is also used to represent density volume; reflects the degree of packing of particles in matter. Gases Plasma Gases spread out to fill the entire space Plasma is a lot like a gas, but the particles given and do not have definite volume; are electrically charged; was first described by have mass; take up space. Irving Langmuir in the 1920s;used in Where: 𝑑 = density fluorescent light bulbs and neon lights; 𝑚 = mass Particles in Gases: lightning is a plasma 𝑉 = volume Thus, density can be expressed in gram per milliliter ü Move freely Particles in Plasma: (g/m ), gram per cubic centimeter (g/cc), kilogram per ü Have LOTS of energy liter (kg/L), pounds per cubic foot (lb /cu. ft.) or any ü Are electrically charged combination of mass and volume units. Densities of ü Have EXTREMELY high energy levels substances change with temperature. For example, at 00C, 1 gram of mercury (Hg) has a volume of 0.07355 mL, but at 200C, the same mass of Hg occupies 0.07382 mL. The density of Hg therefore changes from 13.60 g/mL at 00C to 13.554 g/mL at 200C. Matter & Energy Matter & Energy Density Temperature Sample Problem 2: Temperature- is a measure of the hotness or coldness of an object, is a physical property Sample Problem 1: You have a rock with a volume of 30 that determines the direction of heat flow. Heat always flows spontaneously from a Gold is a precious metal that is chemically unreactive. It is used mainly 𝑐𝑚 and a mass of 60g. What is its substance at higher temperature to one at lower temperature. in jewelry, dentistry, and electronic density? devices. A piece of gold ingot with a Solution: Fahrenheit scale (0F) mass of 301 grams has a volume of Celsius scale (0C) Kelvin (K) = 2.0 g/cm3 60 𝑔 15.6 𝑐𝑚. Calculate the density of gold. ρ= V = 30 𝑐 ü invented by Daniel 𝑚 Gabriel Fahrenheit ü named after Swedish ü the SI base unit of Sample Problem 3: temperature; it is the Solution: Find the volume in L of an object that ü the most commonly Astronomer Anders Celsius absolute temperature has a density of 10.2g/mL and a mass used scale in the scale. We are given the mass and volume and asked to of 30 kg. United States outside calculate the density. the laboratory, ü divides the range Solution: between the freezing - by absolute it means that the zero on the ρ= V point (0 0C) and 𝑚 Therefore, from Eq.1 we write : ü defines the normal Kelvin scale, denoted by 0 K, freezing and boiling boiling point (100 0C) Therefore, 𝑉 = ρ is the lowest temperature 𝑚 301 𝑔 ρ= V = = 19.3 g/cm3 𝑚 15.6 𝑐 points of water to be of water into 100 that can be attained 30,000 g 𝑉 = ρ = 10.2 g/mL =2, 941.1765 mL 𝑚 exactly 32 0 F and degrees. theoretically. 212 0 F, respectively 𝑉 = 2.9412 = 2.9 L Matter & Energy Matter & Energy Temperature Temperature To convert degrees Fahrenheit to degrees Celsius, write: (Eq. 1) To convert degrees Celsius to degrees Fahrenheit: (Eq. 2) Figure 1.4: Comparison of the three temperature scales: Celsius, and Fahrenheit, and the absolute (Kelvin) scales. Note that there are 100 divisions, or Both the Celsius and the Kelvin scales have units of equal magnitude; that is, 100 degrees, between the freezing point and the one degree Celsius is equivalent to one Kelvin. Experimental studies have shown boiling point of water on the Celsius scale, and there that absolute zero on the Kelvin scale is equivalent to -273.15 0C on the Celsius are 180 divisions, or 180 degrees, between the scale. Thus, we can use the following equation to convert degrees Celsius to same two temperature limits on the Fahrenheit Kelvin: scale. The Celsius scale was formerly called the centigrade scale. (Eq. 3) 5  8/30/2024 Matter & Energy Matter & Energy Temperature Specific Gravity Sample Problems: Specific Gravity- is the ratio of the density of a substance to the density of a reference substance (a) Solder is an alloy made of tin and lead that is used in electronic circuits. A certain solder has a (usually water). melting point of 224 0C. What is its melting point in degrees Fahrenheit? (b) Helium has the lowest boiling point of all the elements at 452 0F. Convert this temperature to 𝑠 𝑝.𝑔 𝑟 = 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒 ρ water = 1 g/ 𝑐𝑚 degrees Celsius. 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑠𝑢𝑏𝑠𝑡𝑎𝑛𝑐𝑒 (𝑤𝑎𝑡𝑒𝑟) (c) Mercury, the only metal that exists as a liquid at room temperature, melts at 38.9 0C. Convert its melting point to Kelvins. Other physical properties of matter include Solution: the following: These three parts require that we carry out temperature conversions, so we need Equations 1, 2 and 3. Keep in mind that the lowest temperature on the Kelvin scale is zero (0 K); therefore, it Color can never be negative. Odor Melting point, freezing point, boiling point (b) Here we have: 5 (452 0F - 32 0F) x = 𝟐𝟑𝟑. 𝟑𝟑 0C 9 (c) The melting point of mercury in Kelvin is given by: 38.9 0C + 273.15 = 312. 05 K Changes in Matter What is Energy? Physical Change Physical change: a change in which the identifying properties of a substance remain unchanged; matter changes its appearance, but not its composition; change that affects one or more physical properties of a substance. Energy is the ability to do work. Every action in nature e.g.: melting of ice, breaking of glass, dissolving involves energy. Work is done when matter is moved by sugar in water applying a force. The flight of a bird, the washing of dishes Chemical Change or the polishing of shoes – all these actions require energy. Chemical change: a change in which new Similarly, lifting a book off the table or throwing a baseball substance(s) with new properties are formed; matter changes its composition; substances requires work. The energy of a body or system is therefore are changed into entirely new substances with different properties; that body’s or system’s capacity to do work. e.g.: burning of wood, rusting of iron, decaying of plants Two types Forms of Energy of Energy a) Mechanical Energy- energy due to an object’s motion from one place to another; the bowling ball has mechanical energy; when the ball strikes the pins, mechanical energy is transferred to the pins! b) Chemical Energy- energy that is available for release from chemical reactions. The 1. Potential energy (P.E.): energy due to the chemical bonds in a matchstick store energy that is transformed into thermal energy when position or composition of the object the match is struck. Energy is stored by chemical bonds in an object. When bonds are broken, energy is released as in gasoline, food, coal, and wood. Energy due to height of an object; stored energy e.g.: books on a desk; water at the top of the falls c) Electrical Energy- energy caused by the movement of electrons; easily transported through power lines and converted into other forms of energy; moving electrical charges; 2. Kinetic energy (K.E.): energy due to motion of the electricity from batteries, power lines, lightning object; energy from motion. The faster an object is, the higher the kinetic energy. d) Electromagnetic Energy - Electromagnetic (Radiant) Energy- energy that travels in waves; have electrical and magnetic properties; Light, Magnetism, X-Rays, Radio waves, microwaves, e.g.: books falling; skiing down a mountain; sliding down a ultraviolent and infrared radiation slide; water going over the falls “An object’s total energy is the sum of its P.E. and K.E.” 6  8/30/2024 Forms of Energy Energy Transformations & Conservation: Energy transformation is when energy changes from one form to another. e) Thermal (Heat) Energy- The heat energy of an object determines how active its atoms Energy Conversions: The Law of Conservation of Energy states that energy is neither created nor are. A hot object is one whose atoms and molecules are excited and show rapid movement. destroyed. Energy can change from one form to another or transferred from one object to another. A cooler object's molecules and atoms will show less movement. The internal motion of an objects atoms and molecules. a. Single Transformations Measured by temperature. The faster particles move, the more thermal energy Sometimes, one form of energy needs to be transformed into another to get work done. they have. Atoms and molecules of matter are in constant, random motion, which is the source of thermal energy. e.g.: a toaster transforms electrical energy to thermal energy to toast your bread; a cell phone More motion = more thermal energy transforms electrical energy to electromagnetic energy that travels to other phones b. Multiple Transformations *Temperature is the measure of the thermal energy of a substance. Often, a series of energy transformations is needed to do work. *Heat is the transfer or exchange of thermal energy caused by a temperature difference. Further Examples: The mechanical energy used to strike a match is transformed first to thermal energy. f) Nuclear Energy- Energy stored in the center (nucleus) of an atom; most powerful; The thermal energy causes the particles in the match to release stored chemical energy, which is potential energy only; fission is the splitting of a heavy, unstable nucleus into two lighter transformed to thermal energy and the electromagnetic energy you see as light. nuclei, and fusion is the process where two light nuclei combine together releasing vast amounts of energy (e.g.: the Sun generates its energy by nuclear fusion of hydrogen nuclei into helium.) Instruments that Measure Volume Many academic scientists report their volume measurements with the milliliter unit. On the other hand, analytical chemists tend to work with much smaller volumes, and they would use nanoliter and microliter samples in their laboratory. Volumetric glassware is used to deliver or contain a single volume accurately 04. when filled to the mark. Measurement Figure 1.6: Common volumetric glassware (Source: Chemistry the Central Science, 12th Ed.) Instruments that Measure Mass Tools that Measure Length Balances are utilized to measure the mass of matter. Examples of which are triple beam balances, digital Length is measured using a metric stick or a metric ruler marked in millimeters and centimeters. balances, top-loading digital balances, and analytical balances (for higher sensitivity and accuracy). Most devices used to measure length contain both English and metric markings. In a laboratory, a chemist will commonly use the gram or the even smaller unit milligram. Industrial A measured quantity is usually written as a number with an appropriate unit. In Science, units chemists making larger quantities of material would work with kilograms of materials. Analytical chemists are essential to stating measurements correctly. (industrial or academic), environmental scientists, and toxicologists are typically more concerned with the smaller units like nanograms and or micrograms. Figure 1.8: Length measuring tools. Figure1.7: Some common mass measuring devices found in a Chemistry laboratory. These devices are not drawn to scale relative to one another. 7  8/30/2024 SI Units SI Units The International System of Units, abbreviated SI from the French System International d’Unites is the (1) The kilogram is the metric unit of mass. It's the mass of the international prototype of the main system of measurement units used in science. kilogram: a standard platinum/iridium 1 kg mass housed near Paris at the International Bureau of Weights and Measures (BIPM). (2) The meter is the metric unit of length. It's defined as the length of the path light travels in a vacuum during 1/299,792,458 of a second. (3) The second is defined as the duration of 9,192,631,770 oscillations of radiation corresponding to the transition between the two hyperfine levels of cesium-133. (4) The Kelvin is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The Kelvin scale is an absolute scale, so there is no degree. (5) The mole is defined as the amount of a substance that contains as many entities as there are atoms in 0.012 kilograms of carbon-12. (6) The candela is the luminous intensity, in a given direction, of a source emitting Table 1.1: SI Base Units monochromatic radiation of frequency 540 x 10 hertz with radiant intensity in that direction of 1/683 watt per steradian. (7) The ampere is defined as the constant current that, if maintained in two infinitely long straight parallel conductors with a negligible circular cross-section and placed 1 m apart in a vacuum, would produce a force between the conductors equal to 2 x 10 newtons per meter of length. SI Units SI Units Some units are combinations of SI base units. A derived unit is a unit that results from a mathematical combination of SI base units. Table 1.2: Prefixes Used with SI Units Table 1.3: Derived Units Significant Figures Every measurement is uncertain to some extent. The exactness, or precision, of the measurement depends upon the limitations of the measuring device and the skill with which it is used. 05. The precision of a measurement is indicated by the number of figures used to record it. The digits in a properly recorded measurement are significant figures. Rules in determining the proper number of significant figures: Significant 1. Zeros used only to locate the decimal point are not significant. Zeros that arise as a part of a measurement are significant. o The number 0.0005030 has four significant figures. The zeros after 5 are Figures significant. Those preceding 5 are not significant since they have been added only to locate the decimal point. o The number 600 can be expressed in any of the following ways, depending on how precisely the measurement has been made: 6.00 x 102 (three significant figures) 6.0 x 102 (two significant figures) 6 x 102 (one significant figure) 8  8/30/2024 Significant Figures Significant Figures Rules in determining the proper number of significant figures: Rules in determining the proper number of significant figures: 3. At times, the answer to a calculation contains more figures than are significant. The following rules If a decimal point is indicated in a number such as 200., then all the figures preceding the decimal should be used to round off such a value to a correct number of digits. point are significant. Hence: 1. If the figure following the last number to be retained is less than 5, all the unwanted figures are discarded and the last number is left unchanged. 200.℃ has three significant figures Example: 3.6247 is 3.62 to three significant figures 200 ℃ has one significant figure 250. ℃ has three significant figures 2. If the figure following the last number to be retained is greater than 5, or is 5 with other digits following it, the last figure is increased by 1 and the unwanted figures are discarded. 250℃ has two significant figures 275℃ has three significant figures Example: 7.5647 is 7.565 to four significant figures 6.2501 is 6.3 to two significant figures 2. Certain values, such as those that arise from the definition of terms, are exact. o By definition, there are exactly 1000 mL in one liter (1L). o Values obtained by counting may also be exact. Significant Figures Rules in determining the proper number of significant figures: 05. 3. The result of an addition or subtraction should be reported to the same number of decimal places as that of the term with the least number of decimal places. Example: 161.032 5.6 32.4524 199.0844 Dimensional The result should be reported as 199.1 since the number 5.6 has only one digit following the decimal point. Analysis Dimensional Analysis Dimensional Analysis Dimensional analysis (also called factor label method or unit analysis) is used to For example, 2.54 cm and 1 in. are the same length, in. This relationship allows us to write convert from one set of units to another. This method is used for both simple (feet to two conversion factors: inches) and complex (g/cm3 to kg/gallon) conversions and uses relationships or conversion factors between different sets of units. While the terms are frequently used interchangeably, conversion factors and relationships are different. We use the first factor to convert inches to centimeters. For example, the length in centimeters of an object that is 8.50 in. long is The key to using dimensional analysis is the correct use of conversion factors to change one unit into another. A conversion factor is a fraction whose numerator and denominator are the same quantity expressed in different units. 9  8/30/2024 Dimensional Analysis Dimensional Analysis In general, we begin any conversion by examining the units of the given data and the units we desire. We then ask ourselves what conversion factors we have available to take us from the units of the given quantity to those of the desired one. When we multiply a quantity by a conversion factor, the units multiply and divide as follows: If the desired units are not obtained in a calculation, an error must have been made somewhere. Careful inspection of units often reveals the source of the error. Dimensional Analysis Dimensional Analysis Sample Problem in Converting Units: If a woman has a mass of 115 lb, what is her mass in grams? Solution: Because we want to change from pounds to grams, we look for a relationship between these units of mass. From the above list of conversion factors, we have 1 lb = 453.6 g, cancel pounds and leave grams, we write the conversion factor with grams in the numerator and pounds in the denominator: The answer can be given to only three significant figures, the number of significant figures in 115 lb. The process we have used is diagrammed in the margin. Dimensional Analysis Sample Problem in Converting Units Using Two or More Conversion Factors: The average speed of a nitrogen molecule in air at 25 °C is 515 m/s. Convert this speed to miles per hour. Solution: QUESTIONS? To go from the given units, m/s to the desired units, mi/hr , we must convert meters to miles and seconds to hours. From our knowledge of SI prefixes we know that. From the relationships given above, we find that 1 mi = 1.6093km. Thus, we can convert m to km and then convert km to mi. From our knowledge of time we know that 60s = 1 min 60 min =1 hr and 60 min =1 hr. Thus, we can convert s to min and then convert min to hr. The overall process is applying first the conversions for distance and then those for time, we can set up one long equation in which unwanted units are canceled: 10