CHEM1 week1.docx

Chemistry is a branch of Science that deals with the study of matter and the changes that matter undergoes. It is the study of the composition, structure, properties, transformation of matter, and the energy that is released or absorbed during these processes. The story of the development of Modern...

Chemistry is a branch of Science that deals with the study of matter and the changes that matter undergoes. It is the study of the composition, structure, properties, transformation of matter, and the energy that is released or absorbed during these processes. The story of the development of Modern Chemistry can be divided roughly into five periods: 1.**Practical Arts** (up to 600 BC) Production of metals from ores, manufacture of pottery, brewing, baking, preparation of dyes and drugs The development was based on practical experience alone without reference to underlying chemical principles. Known metals were recorded and listed in conjunction with heavenly bodies 2\. **Ancient Greece** (600 BC to 300 BC) Two important theories: A concept that all substances found on earth are composed of four elements **(earth, air, fire, and water)** in various proportions was proposed by **Aristotle** A theory that matter consists of separate and distinct units called **atoms** was proposed by **Leucippus** and extended later by **Democritus** **Plato** proposed that the atoms of one element differ in shape from the atoms of another. So he believed that atoms of one element could be changed (or transmuted) into atoms of another by changing the shape of the atoms. 3**. Alchemy** (300 BC to 1650 AD) The result of the union of the philosophical tradition of ancient **Greece** and the craft tradition of ancient **Egypt** Attempted to transmute cheap metals to gold (with the use of **Philosopher's Stone**) 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** disproving Aristotle's four elements theory 4\. **Phlogiston Theory** ("Fire Principle") (1650 to 1790) Was formulated by **Johann J. Becher (a German alchemist**) in his book Physica Subterranea where he called it "terra pinguis" (renamed to phlogiston by George Ernst Stahl) Stated that phlogiston, a fire-like element, is contained within combustible things and is released during combustion 5**. Modern Chemistry** (1790-) **Antoine Lavoisier** revolutionized Chemistry by performing quantitative experimentation to arrive at his explanations of several chemical phenomena **The law of conservation of mass** states that there is no detectable change in mass during a chemical reaction. Principal branches: a**. Organic Chemistry** -- the study of carbon (except for a few that are classified as inorganic compounds) b\. **Inorganic Chemistry** -- the study of all the elements except carbon c\. **Analytical Chemistry** -- the identification of the qualitative and quantitative composition 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 The **scientific method** is the general approach to solving problems that involve 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 a 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. **Sir Francis Bacon first documented it.** **-Matter** is anything that occupies space and has mass. Some matter is easy to see (e.g. water, wood), while others are difficult (e.g. air, dust). **Nature of Matter** 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 All matter has its density and inertia. **Mass** is a measure of the quantity of matter and is invariable. A body that is not being acted on by some external force tends 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. based on its chemical composition, matter may be classified as follows:  1\. **Physical properties** are the characteristics of matter that can be changed without changing its composition; directly observable characteristics; a trait of matter that can be observed without changing the chemical composition of the matter; no chemical reactions are involved. **Liquids** take the shape of their container and have definite volumes; have mass; and take up space. Particles in Liquids: ✓Are loosely packed ✓Have medium energy levels ✓Particles flow around each other **Gases** spread out to fill the entire space given and do not have definite volume; have mass; take up space. Particles in Gases: ✓Move freely ✓Have LOTS of energy **Plasma** is a lot like a gas, but the particles are electrically charged; was first described by **Irving Langmuir** in the 1920s; and used in fluorescent light bulbs and neon lights; lightning is a plasma Particles in Plasma: ✓Are electrically charged ✓Have EXTREMELY high energy levels -It is the ratio of mass to volume that reflects the degree of packing of particles in matter. Thus, density can be expressed in grams per milliliter (g/m ), grams per cubic centimeter (g/cc), kilogram per liter (kg/L), pounds per cubic foot (lb /cu. ft.), or any combination of mass and volume units. The densities of 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. The Greek letter **"Rho"** (ρ) is also used to represent density, Density of water: 1g/mL; 1g/cm3; 1kg/L; 62.4lb/ft3 Lowest density element : Hydrogen = 0.0009 g/cm3 Highest density element : Osmium= 23 g/cm3 **Temperature** is a measure of the hotness or coldness of an object and is a physical property that determines the direction of heat flow. Heat always flows spontaneously from a substance at a higher temperature to one at a lower temperature. Three temperature scales are currently in use: The **Fahrenheit scale**, oF (degrees Fahrenheit) invented by Daniel Gabriel Fahrenheit the most commonly used scale in the United States outside the laboratory, defines the normal freezing and boiling points of water to be exactly **32oF and 212oF, respectively.** The **Celsius scale**, Centigrade scale, oC (degrees Celsius) named after **Swedish Astronomer Anders Celsius** divides the range between the freezing point **(0oC) and boiling point (100oC) of water into 100 degrees.**. **Kelvin,** K (Kelvin) is the SI base unit of temperature; it is the absolute temperature scale.  by absolute it means that the zero on the Kelvin scale, denoted by 0 K, is the lowest temperature that can be attained theoretically **Specific Gravity**- is the ratio of the density of a substance to the density of a reference substance (usually water) Other physical properties of matter include the following: a. Color, odor b. Melting point, freezing point, boiling point **Chemical Properties** are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy; A property of matter that describes a substance based on its ability to change into a new substance with different properties. Some of these properties are: Flammability / combustibility Ability to react with oxygen Reactivity with acids **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. e.g.: melting of ice, breaking of glass, dissolving sugar in water **Chemical change**: a change in which new substance(s) with new properties are formed; matter changes its composition; substances are changed into entirely new substances with different properties; e.g.: burning of wood, rusting of iron, decaying of plants **Energy** is the ability to do work. Every action in nature involves energy. **Work** is done when matter is moved by applying a force. The flight of a bird, the washing of dishes or the polishing of shoes-- all these actions require energy. Similarly, lifting a book off the table or throwing a baseball requires work. The energy of a body or system is therefore that body's or system's capacity to do work. **Two Types of Energy**: 1\. **Potential energy (P.E.):** energy due to the position or composition of the object. Energy due to a height of an object; stored energy e.g.: books on a desk; water at the top of the falls 2\. **Kinetic energy (K.E.)**: energy due to motion of the object; energy from motion. The faster an object is, the higher the kinetic energy. e.g.: books falling; skiing down a mountain; sliding down a slide; water going over the falls "An object's total energy is the sum of its P.E. and K.E. 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 chemical bonds in a matchstick store energy that is transformed into thermal energy when 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. 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; electricity from batteries, power lines, lightning d\) **Electromagnetic Energy** Electromagnetic (Radiant) Energy- energy that travels in waves; has electrical and magnetic properties; Light, Magnetism, X-Rays, Radio waves, microwaves, ultraviolent and infrared radiation e\) **Thermal (Heat) Energy**- The heat energy of an object determines how active its atoms are. A hot object is one whose atoms and molecules are excited and show rapid movement. A cooler object\'s molecules and atoms will show less movement. The internal motion of an objects atoms and molecules. Measured by temperature. The faster particles move, the more thermal energy they have. Atoms and molecules of matter are in constant, random motion, which is the source of thermal energy. More motion = more thermal energy. **Temperature** is the measure of the thermal energy of a substance. The hotter an object, the greater the motion of its particles, and the greater the thermal energy **Heat** is the transfer or exchange of thermal energy caused by a temperature difference. **Nuclear Energy**- Energy stored in the center (nucleus) of an atom; most powerful; potential energy only; fission is the splitting of a heavy, unstable nucleus into two lighter nuclei, and fusion is the process where two light nuclei combine releasing vast amounts of energy (e.g.: the Sun generates its energy by nuclear fusion of hydrogen nuclei into helium. **Energy Transformations**: What does flowing water have to do with electricity? You may already know that the mechanical energy of moving water can be transformed into electrical energy. **Energy Conversions**: The Law of Conservation of Energy states that energy is neither created nor destroyed. Energy can change from one form to another or transferred from one object to another. a\. **Single Transformations** Sometimes, one form of energy needs to be transformed into another to get work done. e.g.: a toaster transforms electrical energy into thermal energy to toast your bread; a cell phone transforms electrical energy into electromagnetic energy that travels to other phones Common Energy Transformations: Every day, energy transformations are all around you. Some of these transformations happen inside you! Your body transforms the chemical energy in your food to mechanical energy you need to move your muscles. Chemical energy in food is also transformed to the thermal energy your body uses to maintain its temperature b\. **Multiple Transformations** \- Often, a series of energy transformations is needed to do work. Further Examples: The mechanical energy used to strike a match is transformed first to thermal energy. The thermal energy causes the particles in the match to release stored chemical energy, which is transformed to thermal energy and the electromagnetic energy you see as light. In a car engine, another series of energy conversions occurs. Electrical energy produces a spark. The thermal energy of the spark releases chemical energy in the fuel. The fuel's chemical energy in turn becomes thermal energy. Thermal energy is converted to mechanical energy used to move the car, and to electrical energy to produce more sparks. Transformations Between Potential and Kinetic Energy: One of the most common energy transformations is the transformation between potential energy and kinetic energy. In waterfalls such as Niagara Falls, potential energy is transformed to kinetic energy. The water at the top of the falls has gravitational potential energy. As the water plunges, its velocity increases. Its potential energy becomes kinetic energy The study of Chemistry depends heavily on measurement. For instance, Chemists use measurements to compare the properties of different substances and to assess changes resulting from an experiment. Several common devices enable us to make simple measurements of a substance's properties. **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 when filled to the mark. **Instruments that Measure Mass** -Balances are utilized to measure the mass of matter. Examples of which are triple beam balances, digital balances, top-loading digital balances, and analytical balances (for higher sensitivity and accuracy) In a laboratory, a chemist will commonly use the gram or the even smaller unit milligram. Industrial chemists making larger quantities of material would work with kilograms of materials. Analytical chemists (industrial or academic), environmental scientists, and toxicologists are typically more concerned with the smaller units like nanograms and or micrograms. **Tools that Measure Length** \- Length is **measured using a metric stick or a metric ruler marked in millimeters and centimeters**. Most devices used to measure length contain both English and metric markings. A measured quantity is usually written as a number with an appropriate unit. To say that the distance between Silay City and Bacolod City by car along a certain route is 14 is meaningless. We must specify that the distance is 14 kilometers. In Science, units are essential to stating measurements correctly. The International System of Units, abbreviated SI from the French System International d'Unites is the main system of measurement units used in science.  -For many years scientists recorded measurements in metric units, which are related decimally, that is, by powers of 10. In 1960, however, the General Conference of Weights and Measures, the international authority on units, proposed a revised metric system called the International System of Units (abbreviated SI, from the French System International d'Unites). We use both metric and SI units. Measurements that we will utilize frequently in our study of Chemistry include time, mass, volume, density, and temperature. The **kilogram** is the metric unit of mass. It\'s the mass of the international prototype of the kilogram: a standard platinum/iridium 1 kg mass housed near Paris at the International Bureau of Weights and Measures (BIPM). 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. 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. 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. 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. The **candela** is the luminous intensity, in a given direction, of a source emitting monochromatic radiation of frequency 540 x 1012 hertz with radiant intensity in that direction of 1/683 watt per steradian. 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 10-7newtons per meter of length. Some units are combinations of SI base units. A derived unit is a unit that results from a mathematical combination of SI base units