General Chemistry for Engineering Professionals PDF

Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan GENERAL CHEMISTRY FOR PROFESSIONALS Compiled by Bryan G. Del Rosario Professor  Colegio de San Gabriel Arcang...

Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan GENERAL CHEMISTRY FOR PROFESSIONALS Compiled by Bryan G. Del Rosario Professor  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan CHAPTER 1 FOUNDATIONS OF CHEMISTRY Contents: LAS1: Introduction to Chemistry 2 1. The scientific method and its application in chemistry 2 2. Branches of chemistry and their significance 3 3. Matter and its classification (elements, compounds, 4 mixtures) 4. Physical and chemical properties of matter 5 LAS 2: Measurements and Units 13 1. The International System of Units (SI) 13 2. Scientific notation and significant figures 14 3. Unit conversions and dimensional analysis 15 4. Accuracy, precision, and error in measurements 15 5. Density and its applications 15 LAS 3: Atoms and Molecules 23 1. Atomic theory and structure (protons, neutrons, 23 electrons) 2. Atomic number, mass number, and isotopes 24 3. The periodic table and its organization 25 4. Molecules, molecular formulas, and empirical formulas 26 5. The mole concept and Avogadro's number 26 1  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan LEARNING ACTIVITY 1 TOPIC. Introduction to Chemistry LEARNING OBJECTIVES: By the end of the session, the students will be able to: Name the main types of chemistry. Tell the difference between things made of one stuff (elements) and mixed stuff. Explain how melting ice is different from burning wood. Describe the steps to test an idea in science. LESSON PROPER: 1. The Scientific Method and its Application in Chemistry The scientific method is the systematic approach used in all scientific disciplines, including chemistry, to acquire new knowledge and understanding. It involves a series of steps: Observation: Gathering information about a phenomenon through senses or instruments. Question: Formulating a clear and concise question based on the observation. Hypothesis: Proposing a tentative explanation or prediction that can be tested. Experiment: Designing and conducting controlled tests to gather data. Analysis: Evaluating the data and drawing conclusions about the hypothesis. Conclusion: Summarizing the findings and determining if the hypothesis is supported or rejected. 2  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan Communication: Sharing the results with the scientific community through publications or presentations. In chemistry, the scientific method is crucial for investigating the properties of matter, discovering new compounds, understanding chemical reactions, and developing theories about the behavior of atoms and molecules. It ensures that scientific knowledge is based on empirical evidence and rigorous testing. 2. Branches of Chemistry and Their Significance Chemistry is a vast field with various specialized branches, each focusing on different aspects of matter and its transformations: Organic Chemistry: Studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds, which are essential for life and industry. Inorganic Chemistry: Investigates the properties and behavior of inorganic compounds, which include metals, minerals, and organometallic compounds. Analytical Chemistry: Focuses on the identification, separation, and quantification of chemical components in various substances, playing a crucial role in quality control, environmental monitoring, and forensic science. Physical Chemistry: Applies the principles of physics to study the properties and changes of matter, including thermodynamics, quantum mechanics, and spectroscopy. Biochemistry: Explores thechemical processes within and related to living organisms, including the structure and function of biomolecules like proteins, carbohydrates, lipids, and nucleic acids. Environmental Chemistry: Studies the chemical and biochemical phenomena that occur in natural places. 3  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan Nuclear Chemistry: Deals with the study of nuclear reactions and processes involving atomic nuclei, including radioactivity, nuclear fission, and nuclear fusion. 3. Matter and Its Classification (Elements, Compounds, Mixtures) Matter: Anything that occupies space and has mass. Elements: The simplest form of matter that cannot be broken down into simpler substances by chemical means. Each element is composed of only one type of atom. Examples include hydrogen, oxygen, carbon, and gold. Compounds: Substances formed by the chemical combination of two or more elements in a fixed ratio. They have distinct properties different from their constituent elements. Examples include water (H₂O), carbon dioxide (CO₂), and sodium chloride (NaCl). Mixtures: Combinations of two or more substances (elements or compounds) that are not chemically bonded. They retain their individual properties and can be separated by physical means. Examples include air, seawater, and soil. Mixtures can be further classified as: Homogeneous Mixtures (Solutions): Uniform composition throughout. Examples include salt dissolved in water, sugar dissolved in water. Heterogeneous Mixtures: Non-uniform composition, with visibly distinct components. Examples include sand and water, oil and water. 4  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 4. Physical and Chemical Properties of Matter Physical Properties: Characteristics of matter that can be observed or measured without changing its chemical composition. Examples include: Color Odor Taste Density Melting point Boiling point Solubility Hardness Electrical conductivity Thermal conductivity Chemical Properties: Characteristics of matter that describe its potential to undergo chemical reactions and form new substances. Examples include: Flammability Reactivity with acids or bases Oxidation (rusting) Decomposition 5  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan POST-CLASS ACTIVITIES I. Identification: Provide the the answers demanded by each question. Write your answer on the blanks provided. 1. What is the systematic approach used in all scientific disciplines to acquire new knowledge? 2. What are the steps of the scientific method? 3. Which branch of chemistry studies carbon-containing compounds? 4. What type of chemistry focuses on the identification and quantification of chemical components? 5. What branch of chemistry applies the principles of physics to study the properties and changes of matter? 6. Define matter. 7. What is the simplest form of matter that cannot be broken down into simpler substances by chemical means? 8. What are substances formed by the chemical combination of two or more elements in a fixed ratio? 9. What are combinations of two or more substances that are not chemically bonded? 10. What are the two types of mixtures? 11. Give an example of a homogeneous mixture. 12. Give an example of a heterogeneous mixture. 13. What are the characteristics of matter that can be observed or measured 6  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan without changing its chemical composition? 14. Name three examples of physical properties. 15. What are the characteristics of matter that describe its potential to undergo chemical reactions and form new substances? 16. Give two examples of chemical properties. 17. What is the difference between organic and inorganic chemistry? 18. What is the significance of analytical chemistry in various fields? 19. How does physical chemistry relate to physics? 20. What is the primary focus of biochemistry? II. True or False. Write TRUE if the statement is correct, Write FALSE if otherwise. Write your answer on the blanks provided. 1. Water (H₂O) is an element. 2. Organic chemistry is the study of carbon-containing compounds. 3. The scientific method begins with formulating a hypothesis. 4. A compound has properties that are different from the elements that make it up. 5. Mixtures cannot be separated by physical means. 6. The freezing point of a substance is a chemical property. 7. All elements are naturally occurring. 8. Rusting is a chemical change. 7  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 9. A solution is a type of heterogeneous mixture. 10. The atomic number of an element is the number of protons in its nucleus. 11. Electrons are found in the nucleus of an atom. 12. The chemical symbol for gold is Ag. 13. An acid has a pH value greater than 7. 14. A change in state, like melting or boiling, is a physical change. 15. Biochemistry is the study of chemical processes in living organisms. 16. The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. 17. Density is a chemical property. 18. The periodic table organizes elements by their atomic number. 19. Nuclear chemistry deals with the study of atomic nuclei and their reactions. 20. All compounds are molecules, but not all molecules are compounds. III. Multiple-Choice. Encircle the letter of the correct answer. 1. Which of the following is NOT a state of matter? (a) Solid (b) Liquid (c) Gas (d) Plasma (e) Vacuum 2. Which branch of chemistry deals with the study of carbon compounds? (a) Inorganic Chemistry (b) Organic Chemistry (c) Analytical Chemistry 8  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (d) Physical Chemistry 3. What is the smallest unit of an element that retains the properties of that element? (a) Atom (b) Molecule (c) Compound (d) Mixture 4. A chemical reaction that releases heat is called: (a) Endothermic (b) Exothermic (c) othermic (d) Isothermic 5. Which of the following is a noble gas? (a) Oxygen (b) Nitrogen (c) Helium (d) Chlorine 6. The pH scale measures: (a) Temperature (b) Acidity/alkalinity (c) Density (d) Concentration 7. What is the chemical formula for water? (a) H₂O₂ (b) H₂O (c) HO₂ (d) HO 8. The process of a solid changing directly into a gas is called: (a) Condensation (b) Sublimation (c) Evaporation (d) Deposition 9. Which of the following is NOT a type of chemical bond? (a) Ionic bond (b) Covalent bond (c) Metallic bond 9  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (d) Hydrogen bond (e) Nuclear bond 10. The atomic number of an element represents: (a) Number of neutrons (b) Number of protons (c) Number of electrons (d) Atomic mass 11. Which element is the most abundant in the Earth's crust? (a) Oxygen (b) Silicon (c) Aluminum (d) Iron 12. The process of splitting an atomic nucleus is called: (a) Nuclear fusion (b) Nuclear fission (c) Nuclear decay (d) Nuclear synthesis 13. What is the name of the table that organizes all known elements? (a) Elemental table (b) Periodic table (c) Chemical table (d) Atomic table 14. Which of the following is a property of acids? (a) Turns litmus paper blue (b) Has a pH greater than 7 (c) Tastes bitter (d) Reacts with metals to produce hydrogen gas 15. A substance that speeds up a chemical reaction without being consumed is called: (a) Catalyst (b) Inhibitor (c) Reactant (d) Product 16. Which law states that energy cannot be created or destroyed, only transformed from one form to another? 10  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (a) Law of conservation of mass (b) Law of conservation of energy (c) Law of definite proportions (d) Law of multiple proportions 17. Which of the following is an example of a chemical change? (a) Ice melting (b) Sugar dissolving in water (c) Paper burning (d) Water boiling 18. The study of the rates of chemical reactions is called: (a) Thermodynamics (b) Kinetics (c) Equilibrium (d) Stoichiometry 19. What is the name of the negatively charged subatomic particle? (a) Proton (b) Neutron (c) Electron (d) Positron 20. Which of the following is NOT a type of radioactive decay? (a) Alpha decay (b) Beta decay (c) Gamma decay (d) Delta decay IV. Essay. Answer each question briefly but concisely. 1. The Periodic Table: Discuss the organization of the periodic table, explaining how elements are arranged based on their atomic structure and properties. Provide examples of how the periodic table can be used to predict the behavior of elements in chemical reactions. 11  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 2. Chemical Bonding: Compare and contrast the three main types of chemical bonds: ionic, covalent, and metallic. Describe the factors that determine which type of bond will form between atoms, and how these bonds influence the properties of the resulting compounds. 3. Acids and Bases: Explain the concept of acids and bases, including the different definitions (Arrhenius, Bronsted-Lowry, Lewis). Discuss the pH scale and how it is used to measure the acidity or alkalinity of a solution. Provide examples of common acids and bases and their applications in everyday life. 4. Chemical Kinetics: Describe the factors that affect the rate of a chemical reaction, such as temperature, concentration, surface area, and catalysts. Explain how the collision theory and the concept of activation energy help us understand reaction rates. Discuss the importance of reaction kinetics in industrial processes and biological systems. 5. Organic Chemistry: Define organic chemistry and explain its significance in various fields, including medicine, agriculture, and materials science. Discuss the unique properties of carbon that make it the basis for all organic compounds. Provide examples of important classes of organic compounds, such as hydrocarbons, carbohydrates, proteins, and nucleic acids, and their roles in living organisms. 12  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan LEARNING ACTIVITY 2 Topic: Measurements and Units: The Foundation of Science Learning Objectives: After the session, the learners will be able to: Identify the seven base units of the SI system. Understand scientific notation and significant figures. Perform unit conversions. Calculate density. Write numbers in scientific notation. Perform unit conversions using dimensional analysis. Use a calculator to solve density problems. LESSON PROPER: Measurements and units are the backbone of scientific understanding, enabling us to quantify the world around us and communicate those observations precisely. 1. The International System of Units (SI): A Universal Language Why SI? The SI system is the global standard for measurement. It ensures consistency and clarity when scientists, engineers, and others share data across borders and disciplines. Base Units: The seven fundamental SI units define the building blocks of all measurements: o Length (meter, m): The distance light travels in a vacuum in 1/299,792,458 of a second. o Mass (kilogram, kg): Originally defined by a physical prototype, now based on fundamental constants. 13  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan o Time (second, s): The duration of 9,192,631,770 periods of radiation corresponding to a specific atomic transition. o Electric Current (ampere, A): The flow of electric charge at a rate of one coulomb per second. o Temperature (kelvin, K): An absolute scale where zero kelvin is absolute zero, the theoretical lowest temperature. o Amount of Substance (mole, mol): The amount of a substance that contains as many elementary entities as there are atoms in 0.012 kg of carbon-12. o Luminous Intensity (candela, cd): The luminous power per unit solid angle emitted by a specific light source. Derived Units: These units are formed by combining base units, often using multiplication or division. Examples include: o Area (square meter, m^2) o Volume (cubic meter, m^3) o Speed (meter per second, m/s) o Acceleration (meter per second squared, m/s^2) o Force (newton, N = kg*m/s^2) 2. Scientific Notation and Significant Figures: Expressing Precision Scientific Notation: A shorthand way to write very large or very small numbers, making them easier to manage and compare. For example, the speed of light, 300,000,000 m/s, is more concisely expressed as 3.00 x 10^8 m/s. Significant Figures: Indicate the precision of a measurement. They are the digits in a number that are known with certainty plus one estimated digit. The number of significant figures depends on the measuring instrument and the smallest unit it can reliably measure. 14  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 3. Unit Conversions and Dimensional Analysis: Bridging the Gaps Unit Conversions: Essential for comparing and combining measurements made in different units. Conversion factors are ratios used to change from one unit to another (e.g., 1 mile = 1.609 kilometers). Dimensional Analysis: A powerful tool for checking the validity of calculations. By tracking units through a calculation, you can ensure that the final answer has the correct units and dimensions. 4. Accuracy, Precision, and Error: Understanding Limitations Accuracy: How close a measurement is to the true or accepted value. Precision: How close a set of measurements are to each other, regardless of their accuracy. Error: The inevitable deviation of a measurement from the true value. Errors can be random (due to chance fluctuations) or systematic (due to flaws in the measuring instrument or procedure). 5. Density: A Key Property Density (mass per unit volume, kg/m^3 or g/cm^3): A fundamental property of matter that helps identify substances and predict their behavior. Applications: Density is used in various fields: o Materials Science: To select materials with specific properties for engineering applications. o Oceanography: To study ocean currents and the distribution of marine life. o Geology: To identify rocks and minerals. 15  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan POST-CLASS ACTIVITIES I. Identification: Provide the answers demanded by each question. Write your answer on the blanks provided. 1. What is the standard unit for length in the SI system? 2. How can very large or very small numbers be expressed concisely using powers of ten? 3. How many significant figures are in the measurement 0.02050 kg? 4. What is the term for the ratio used to convert one unit to another? 5. What technique can be used to check the validity of calculations by tracking units? 6. What describes how close a measurement is to the true or accepted value? 7. What describes how close a series of measurements are to each other? 8. What is the term for the mass per unit volume of a substance? 9. What is the standard unit for mass in the SI system? 10. What is the standard unit for time in the SI system? 11. What is the standard unit for electric current in the SI system? 12. What is the standard unit for temperature in the SI system? 13. What is the standard unit for the amount of substance in the SI system? 16  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 14. What is the standard unit for luminous intensity in the SI system? 15. What is a common unit for volume in the metric system? 16. What is the formula for calculating density? 17. What type of error is caused by a flaw in the measuring instrument? 18. What type of error is caused by random fluctuations in the measurement process? 19. What is the prefix in the metric system that means one thousandth (1/1000)? 20. What is the prefix in the metric system that means one thousand (1000)? II. True or False. Write TRUE if the statement is correct, Write FALSE if otherwise. Write your answer on the blanks provided. 1. Is the SI unit for time the minute? 2. Is scientific notation used to express very large or small numbers? 3. Is the kilogram the SI base unit for mass? 4. Is dimensional analysis a way to check if calculations are correct? 5. Do precision and accuracy mean the same thing in measurement? 6. Is density calculated by dividing mass by volume? 7. Is the meter a unit of volume? 8. Is the SI unit for temperature Celsius? 9. Do significant figures indicate the precision of a measurement? 10. Is a conversion factor used to change from one unit to another? 11. Are random errors predictable and can be eliminated? 12. Are systematic errors consistent and can affect all measurements? 17  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 13. Does the prefix "kilo-" mean one hundredth (1/100)? 14. Does the prefix "milli-" mean one thousandth (1/1000)? 15. Is the liter a unit of mass? 16. Is the newton a derived unit of force? 17. Are zeroes at the end of a decimal number never significant? 18. Is the SI unit for luminous intensity the lumen? 19. Is a micrometer a smaller unit of length than a millimeter? 20. Can density be used to identify unknown substances? III. Multiple-Choice. Encircle the letter of the correct answer. 1. The standard unit for length in the SI system is: (a) foot (b) mile (c) meter (d) inch 2. Which of the following is the correct scientific notation for 0.000035? (a) 3.5 x 10^-5 (b) 3.5 x 10^5 (c) 35 x 10^-6 (d) 0.35 x 10^-4 3. How many significant figures are in the measurement 10.050 grams? (a) three (b) four (c) five (d) six 4. What is used to convert between different units of measurement? (a) dimensional analysis (b) accuracy (c) precision 18  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (d) conversion factor 5. The degree of exactness of a measurement is known as: (a) precision (b) accuracy (c) error (d) density 6. Which of the following is the formula for density? (a) mass x volume (b) mass / volume (c) volume / mass (d) mass + volume 7. The SI base unit for electric current is: (a) ampere (b) volt (c) ohm (d) watt 8. The SI base unit for temperature is: (a) Celsius (b) Fahrenheit (c) Kelvin (d) Rankine 9. Which of the following is NOT a base unit in the SI system? (a) candela (b) mole (c) liter (d) kilogram 10. The closeness of a measurement to its true value is called: (a) precision (b) error (c) accuracy (d) density 11. A measurement of 5.6700 grams has how many significant figures? (a) two (b) three (c) four 19  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (d) five 12. The method of converting units by multiplying by a factor of one is known as: (a) unit analysis (b) dimensional analysis (c) conversion analysis (d) factor analysis 13. The prefix "mega-" (M) means: (a) 10^-6 (b) 10^-3 (c) 10^3 (d) 10^6 14. The prefix "micro-" (µ) means: (a) 10^-9 (b) 10^-6 (c) 10^6 (d) 10^9 15. The formula to convert Celsius to Kelvin is: (a) K = °C + 273.15 (b) K = °C - 273.15 (c) K = °C / 273.15 (d) K = °C x 273.15 16. Which of the following is a derived unit? (a) meter (b) kilogram (c) second (d) newton 17. What type of error is due to inconsistencies in the measuring instrument? (a) random error (b) systematic error (c) human error (d) parallax error 18. The SI unit for luminous intensity is: (a) lumen (b) lux 20  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan (c) candela (d) watt 19. Which prefix represents 1/100th of a base unit? (a) deci- (b) centi- (c) milli- (d) micro- 20. Which of the following is NOT a unit of volume? (a) liter (b) cubic meter (c) milliliter (d) kilogram IV. Essay. Answer each question briefly but concisely. 1. Explain the importance of the International System of Units (SI) in scientific research and communication. Discuss the advantages of using a standardized system of measurement and provide examples of how the SI system is applied in different fields of science. 2. Discuss the concepts of accuracy and precision in scientific measurements. Explain how they differ, why both are important, and how they relate to the concept of error. Provide examples of how to improve accuracy and precision in measurements. 3. Describe the process of dimensional analysis and explain its role in ensuring the validity of calculations involving units. Provide a step- by-step example of how dimensional analysis can be used to convert between different units of measurement. 4. Explain the concept of density and its significance in various scientific disciplines. Discuss how density is calculated, how it can 21  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan be used to identify substances, and how it affects the behavior of materials in different environments. 5. Evaluate the role of scientific notation and significant figures in expressing the precision of measurements. Explain why scientific notation is useful for representing very large or very small numbers, and discuss the rules for determining significant figures in calculations. 22  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan LEARNING ACTIVITY 3 TOPIC. Atoms and Molecules: Unlocking the Secrets of Matter LEARNING OBJECTIVES: By the end of the session, the students will be able to: Define key terms related to atoms and molecules (e.g., atom, element, molecule, isotope, valence electron). Describe the structure of an atom, including the location and charge of subatomic particles. Identify the atomic number and mass number of an element from the periodic table. Differentiate between molecular and empirical formulas. Explain the mole concept and its relationship to Avogadro's number. LESSON PROPER: 1. Atomic Theory and Structure: The Heart of Matter What is an atom? Imagine the tiniest grain of sand you can possibly see. Now, imagine something a million times smaller! That's roughly the size of an atom – the fundamental building block of everything around us. atom with nucleus (protons and neutrons) and electron shells 23  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan Subatomic Particles: The Inner Workings o Protons (p+): These positively charged particles reside in the nucleus, the dense core of the atom. The number of protons defines the element (e.g., all carbon atoms have 6 protons). o Neutrons (n0): These neutral particles share the nucleus with protons, contributing to the atom's mass. o Electrons (e-): These negatively charged particles whiz around the nucleus in distinct energy levels called shells or orbitals. The arrangement of electrons determines an atom's chemical behavior. The Quantum Leap: Electron Energy Levels o Electrons don't just orbit randomly; they occupy specific energy levels. Think of it like a staircase, where each step represents a different energy level. o The lowest energy level is closest to the nucleus, and higher energy levels are further away. Electrons can jump between levels by absorbing or releasing energy. o Valence Electrons: The electrons in the outermost shell are called valence electrons. They play a crucial role in chemical bonding. 2. Atomic Number, Mass Number, and Isotopes: Identity and Variations Atomic Number (Z): This is the atom's ID card. It tells us the number of protons and defines the element. It's like a fingerprint – unique to each element. Mass Number (A): This is the atom's weightlifter stat – the total count of protons and neutrons in the nucleus. Isotopes: Nature's Variety Pack 24  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan o Isotopes are like siblings of the same element – they share the same number of protons (same atomic number) but differ in the number of neutrons (different mass numbers). o Some isotopes are stable, while others are radioactive, meaning they decay over time and emit radiation. 3. The Periodic Table: The Chemist's Roadmap periodic table Organization: The periodic table is a brilliant arrangement of elements based on their atomic number and chemical properties. Groups (Columns): Elements in the same group share similar chemical behaviors because they have the same number of valence electrons. 25  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan o Example: Alkali metals (Group 1) are highly reactive, while noble gases (Group 18) are very stable. Periods (Rows): Moving across a period, you'll see a gradual change in properties as the number of protons and electrons increases. Metals, Nonmetals, Metalloids: The periodic table is divided into these broad categories based on characteristics like luster, conductivity, and reactivity. Interactive Element: Can you find the element with atomic number 17 on the periodic table? What group does it belong to? What are some of its properties? 4. Molecules and Formulas: From Atoms to Compounds Molecule: When two or more atoms join hands (through chemical bonds), they form a molecule. Molecular Formula: This is like a molecule's recipe – it tells us the exact number and type of atoms in a molecule (e.g., CO₂ for carbon dioxide). Empirical Formula: This is the simplified version of the recipe, showing the smallest whole-number ratio of atoms (e.g., CH₂O for glucose, which has a molecular formula of C₆H₁₂O₆). 5. The Mole and Avogadro's Number: Counting the Uncountable The Mole (mol): Imagine you have a dozen eggs. A mole is a similar concept, but instead of 12, it represents a mind- boggling number of particles – 6.022 x 10²³ to be exact! This is Avogadro's number. Why the Mole? Atoms and molecules are incredibly tiny. The mole allows us to work with manageable quantities of substances in the lab. 26  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan POST-CLASS ACTIVITIES I. Identification: Provide the answers demanded by each question. Write your answer on the blanks provided. 1. The smallest unit of an element that retains its chemical properties. 2. The positively charged particle found in the nucleus of an atom. 3. The neutral particle found in the nucleus of an atom. 4. The negatively charged particle that orbits the nucleus. 5. The dense central core of an atom. 6. The specific energy levels that electrons occupy around the nucleus. 7. The number of protons in an atom, which defines its element. 8. The total number of protons and neutrons in an atom. 9. Atoms of the same element with different numbers of neutrons. 10. The organized arrangement of elements based on their atomic number and properties. 11. Vertical columns on the periodic table containing elements with similar properties. 12. Horizontal rows on the periodic table indicating the number of electron shells. 13. Shiny, malleable elements that are good conductors of heat and electricity. 14. Elements that are typically dull, brittle, and poor conductors. 27  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 15. Elements with properties intermediate between metals and nonmetals. 16. A group of two or more atoms held together by chemical bonds. 17. A formula showing the exact number and type of atoms in a molecule. 18. A formula showing the simplest whole-number ratio of atoms in a compound. 19. The unit of measurement representing 6.022 x 10²³ particles. 20. The scientist associated with the number 6.022 x 10²³. II. True or False. Write TRUE if the statement is correct, Write FALSE if otherwise. Write your answer on the blanks provided. 1. All matter is made up of atoms. 2. Electrons are found inside the nucleus of an atom. 3. The atomic number of an element is the number of neutrons it has. 4. Isotopes are atoms of the same element with different mass numbers. 5. The periodic table organizes elements based on their chemical properties. 6. Elements in the same group on the periodic table have the same number of valence electrons. 7. Metals are typically poor conductors of heat and electricity. 8. A molecule is formed when two or more atoms chemically bond together. 9. The empirical formula of a compound shows the exact number of atoms in a molecule. 10. Avogadro's number represents the number of atoms or molecules in one mole of a substance. 28  Colegio de San Gabriel Arcangel PACUCOA Accredited – Level 3 Status COLLEGE DEPARTMENT City of San Jose del Monte, Bulacan 11. A mole of carbon atoms has the same mass as a mole of oxygen atoms. 12. The chemical symbol for gold is Ag. 13. The most common isotope of hydrogen has one proton and one neutron. 14. Nonmetals tend to gain electrons in chemical reactions. 15. The atomic mass of an element is always a whole number. 16. The elements in the first period of the periodic table are all gases at room temperature. 17. Ionic bonds form when atoms share electrons. 18. The empirical formula for water is H₂O. 19. The elements in Group 18 of the periodic table are known as noble gases. 20. The smallest unit of a compound is a molecule. III. Multiple-Choice. Encircle the letter of the correct answer. 1. Which subatomic particle has a positive charge? a) Neutron b) Electron c) Proton d) Photon 2. What is the atomic number of an element? a) The number of neutrons in the nucleus b) The number of protons and neutrons in the nucleus c) The number of protons in the nucleus d) The number of electrons in the outer shell 3. Which of the following is an isotope of carbon-12? a) Carbon-13 b) Nitrogen-14 c) Oxygen-16 d) Boron-11 4. Elements in the same group on the periodic table have: 29