Chemistry Lesson 1 PDF

Chemistry is defined as the study of matter → Hypothesis: A tentative explanation for and the changes it undergoes. It is often referred to observations. as the "central science" because it connects and → Law: A concise statement describing a overlaps with various scientific...

Chemistry is defined as the study of matter → Hypothesis: A tentative explanation for and the changes it undergoes. It is often referred to observations. as the "central science" because it connects and → Law: A concise statement describing a overlaps with various scientific disciplines such as consistent relationship in nature. biology, physics, geology, and ecology. → Theory: A comprehensive explanation of a Universality of Chemistry phenomenon based on extensive evidence. Chemistry is present in everyday life and can be Matter observed in various contexts: Defined as anything that occupies space and has 1. Health: The COVID-19 pandemic has mass. brought attention to critical the role chemistry plays in the development of vaccines and medications. 2. Energy and Environment: Chemistry is the basis of ideas like solar panels and battery energy storage. 3. Materials and Technology: Chemical principles perform a significant part in the development of batteries and other Mixtures: combination of two or more substances electronic devices. where each retains its identity. (e.g saltwater) 4. Agriculture: Chemistry is engaged in → Homogeneous: uniform composition developing effective fertilizers and throughout. (e.g sugar dissolved in water) composting strategies. → Heterogeneous: non-uniform 5. Outer Space: Chemistry is essential to composition. (e.g oil and water) interpreting the makeup of the universe and Pure Substances: matter with a constant its celestial bodies. composition and distinct properties. (e.g water) Macroscopic vs Microscopic → Compounds: substance composed of Chemistry aims to help students think like atoms of two or more elements chemists by bridging the macroscopic world chemically united in fixed position. (observable phenomena) with the microscopic → Elements: substance that cannot be world (atomic and molecular interactions). For separated in simpler substances. example, the rusting of iron nails involves a chemical reaction between iron and oxygen, which Phases of Matter can be understood through chemistry. can be interconverted without changing the composition of the substance. Scientific Method → Solid: definite shape and volume, with All sciences, including the social sciences, employ a closely packed molecules. variation of a systematic approach to research. → Liquid: definite volume but no definite → Qualitative: consisting of general shape, with molecules that can move past observations about the systems. one another. → Quantitative: comprising numbers obtained → Gas: no definite shape or volume, with by various measurements of the system. widely spaced molecules. Key Components: Properties of Matter It is observable. It can be classified into: → Physical Properties: can be measured and observed without changing the composition or identity of a substance. It is observable without changing the substance. (e.g color, mass) Temperature of Matter → Chemical Properties: Observe through Is measured in degrees Celsius, Fahrenheit, or chemical change. It involves the substance’s Kelvin, with Kelvin being the SI base unit. reactivity and ability to undergo chemical changes. (e.g flammability) Measurement of Matter It can be categorized into: → Intensive Properties: doesn’t depend on how much matter is being considered. → Extensive Properties: depends on how much matter is being considered. Temperature Problem The International System of Units (SI) is used for Problem: Solder is an alloy made of tin and lead measurements, with base units for length (meter), that is used in electronic circuits. A certain solder mass (kilogram), and volume (liter). Density is a key has a melting point of 224℃. What is its melting derived unit, calculated as mass divided by volume. 𝑚 point in degrees Fahrenheit? 𝑑= 𝑣 Solution: Mass is the measure of the amount of matter in an object. Weight is the force that gravity exerts on an object. Density Problems Problem #1: Gold is a precious metal that is Scientific Notation of Matter chemically unreactive. It is used mainly in jewelry, It is used to express very large or small numbers, dentistry, and electronic devices. A piece of gold facilitating easier calculations and reducing errors. ingot with a mass of 301 g has a volume of 15.6m³. Where N is a number between 1 and 10 and n, the Calculate the density of gold. exponent, is a positive or negative integer (whole Solution: number). Any number expressed in this way is said to be written in scientific notation. Example: Express 568.762 in scientific notations: Problem #2: The density of mercury, the only metal 568.762 = 5.68762 x 10² that is a liquid at room temperature, is 13.6 g/mL. Express 0.00000772 in scientific notation: Calculate the mass of 5.50 mL of the liquid. 0.00000772 = 7.72 x 10⁻⁶ Solution: The rules for determining significant figures include: 1. Any digit that is not zero is significant.  2. Zeros between nonzero digits are Solution: significant. 3. Zeros to the left of the first nonzero digit are not significant. 4. If a number is greater than 1, then all the zeros written to the right of the decimal point count as significant figures. 5. For numbers that don’t contain decimal points, the trailing zeros are not significant. Add/Subtract - The final answer must follow the number of given with least decimal point - e.g 1.29 + 1.1 = 2.39 = 2.4 Multiply/Divide - The final answer must follow the number of given with least significant figures. - 1.29 x 1.199 = 1.54671 = 1.55 Accuracy and Precision Accuracy tells us how close a measurement is to the true value of the quantity that was measured. Precision refers to how closely two or more measurement of the same quantity agree with one another. Dimensional Analysis A method used to convert units and solve problems involving measurements. It involves using conversion factors to ensure that units cancel appropriately, leading to the desired unit in the final answer. Dimensional Analysis Problem Problem: A person’s average daily intake of glucose (a form of sugar) is 0.0833 (lb). What is this mass in milligrams (mg)? (1 lb = 453.6 g) Pounds → Grams → Milligrams