Week 1 - Nature of Matter Part 1 PDF

NATURE OF MATTER RENATO M. VERGARA, PhD  Fundamental Laws of Chemistry Objectives: 1. Explain how the fundamental laws of chemistry led to the formulation of modern atomic theory. 2. Perform the fundamental laws of chemistry in laboratory experiments. Fundamental Laws of Chemistry 1....

NATURE OF MATTER RENATO M. VERGARA, PhD  Fundamental Laws of Chemistry Objectives: 1. Explain how the fundamental laws of chemistry led to the formulation of modern atomic theory. 2. Perform the fundamental laws of chemistry in laboratory experiments. Fundamental Laws of Chemistry 1. Law of Conservation of mass 2. Law of Definite Composition or Law of Definite Proportions 3. Law of Multiple Proportions Law of Conservation of mass Law of Conservation of mass This Law of Conservation of Mass became the foundation of Stoichiometric calculations particularly in determining the amount of reactants and products involved in each chemical reaction. For short, mass cannot be destroyed during chemical reaction, but is always conserved. Law of Conservation of mass And by the late 1700, chemist accepted the definition of an element as “substance that cannot be broken down into a simpler substance by ordinary chemical means. Law of Definite Composition or Law of Definite Proportions Decades after the formulation of Law of Conservation of Mass, Joseph-Louis Proust, established the Law of Definite Proportion or Law of Definite Composition. sometimes called Proust's law or the Law of Constant Composition. A chemical compound always contains the same elements in the same percent by mass. If two elements combine to form a given compounds, they always combined in a fixed proportion. Law of Definite Composition or Law of Definite Proportions Example: Water (H2O) ▪ Being a chemical compound, water is written as H2O. ▪ Therefore, water (H2O) is made up of atoms of Hydrogen and Oxygen. If two (2) atoms of Hydrogen combine with one (1) atom of Oxygen, water is created. Law of Definite Composition or Law of Definite Proportions Therefore, 𝐻2 𝑂 has a molecular weight of: ▪ Looking at your periodic table of elements: 2 atoms of Hydrogen = (2) (1g/mol) Hydrogen atom has an = 2 g/mol atomic mass of 1 g/mol. 1 atom of Oxygen = (1) (16 g/mol) Oxygen atom has an = 16 g/mol atomic mass of 16 g/mol. Molecular weight of H2O = 2 g/mole + 16 g/mol = 18 g/mol  Law of Definite Composition or Law of Definite Proportions 2 𝑔/𝑚𝑜𝑙 % 𝑏𝑦 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐻 = 18 𝑔/𝑚𝑜𝑙 𝑥 100% = 11% % by weight of the components of H2O % 𝑏𝑦 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝐻=(2 𝑔/𝑚𝑜𝑙)/(18 𝑔/𝑚𝑜𝑙) 𝑥 100% = 11% 16 𝑔/𝑚𝑜𝑙 % 𝑏𝑦 𝑤𝑖𝑒𝑔ℎ𝑡 𝑜𝑓 𝑂 = 𝑥 100% = 89% 18 𝑔/𝑚𝑜𝑙 ▪ This means that H2O is made up of 11% hydrogen and 89% oxygen. According to the law of definite composition, 11% hydrogen and 89% oxygen must be combined for the water to be created. Water or H2O cannot be created if you will combine 30% hydrogen and 70% oxygen, because the proportions are not correct. Law of Multiple Proportions o It states that, the masses of one element which combine with a fixed mass of the second element are in a ratio of whole numbers such as 2:1, 1:1, 2:3, etc. o Example: ▪ Oxides of nitrogen Nitrogen has an atomic mass of 14 amu nitrogen monoxide (NO) or 14 g/mol and Oxygen has an atomic nitrogen dioxide (NO2) mass of 16 amu or 16 g/mol. nitrogen trioxide (NO3) nitrogen tetroxide (NO4) Law of Multiple Proportions Mass of Nitrogen is fixed with 14 amu or 14 g/mol, while the mass of Oxygen varies: For NO, mass of N=14 amu, O (1 x 16 amu) = 16 amu For NO2, mass of N=14 amu, O (2 x 16 amu) = 32 amu For NO3, mass of N=14 amu, O (3 x 16 amu) = 48 amu For NO4, mass of N=14 amu, O (4 x 16 amu) = 64 amu Therefore, following the Law of Multiple Proportions, the mass ratio of nitrogen to oxygen is (N:O) For NO, 14:16 1:1. For NO2, 14:32 1:2. For NO3, 14:48 1:3. For NO4, 14:64 1:4. Law of Multiple Proportions When carbon and oxygen are combined two compounds of Sample 2: oxides will be formed. One of the oxides that may formed contains 42.9% carbon and the other one is 27.3% carbon. Prove this using the law of Multiple Proportions.  Nature and States of Matter Objectives: 1. Realized that substances are made up of tiny particles. 2. Identify and describe the arrangement, spacing, and motion of the particles in each of the three phases of matter. 3. Identify the phase change that occurs in matter.  Nature and States of Matter The Particle Nature of Matter Ancient Greek Philosophers believed that matter was made up of single element Anaximenes (flourished c. Thales of Miletus (flourish Heraclitus (C. 540-480 545 BCE)– he believed 6th century BCE) – believed BCE) – believed that the that the primal element that the primal element was primal element was fire. was air water  The Particle Nature of Matter ▪ From these ideas Empedocles proposed that all matter was made up of four fundamental elements – earth, air, fire, and water. ▪ Empedocles (c. 490 – 430 BCE) - believed that differences in characteristics and behavior of materials are the product of varying proportions of these four fundamental elements. ▪ The problem with the idea of Empedocles is that, when a material is broken down, the four fundamental elements cannot be recovered. ▪ The only important contribution of Empedocles idea is that it opens the idea of the important concept, now known as the Law of Constant Proportion. Around 400 BCE, Leucippus (flourished 5th century BCE) and his student Democritus (flourished c. 460 – 370 BCE) They wondered what would happen on a piece of gold if it were cut indefinitely, later they concluded that there must be a smallest unit gold that cannot be further broken down without it ceasing to be gold. They concluded that there must be a smaller unit of gold that cannot be further broken down without ceasing it to be gold. They called this unit as Atomos, meaning “indivisible or uncuttable.” 5 Main Principles of Leucippus and Democritus. 1. All matters are made up of too tiny particles that cannot be seen by the naked eye called atom. Atom cannot be broken down further into smaller pieces. Varieties of matter results from the combinations of breaking apart of this atom. 2. Atoms are in constant motion around the void (empty space). 3. Atoms are completely solid (billiard ball model). 4. Atoms are uniform, it has no internal structure. 5. Atoms have different sizes and shapes.  Epirucus of Samos (341 – 270 BCE) He popularized the philosophy of atom or atomism. Philosophy that matter is made up of atom. He also added that atom have different weights and all atoms have the same speed regardless of its size.  The philosophy of atomists was highly opposed by mor historically famous philosopher – Aristotle. He agreed with Empedocles that matter was made up of four (fire, air, earth and water) fundamental elements in varying proportions. He believed that one element could be transformed into another element. He added the fifth fundamental elements, the Aether. A matter found outside the earth and the moon. He popularized the Continuous theory. A theory that matter can be divided indefinitely without changing the fundamental characteristics of the materials. Completely opposite to atomists. Conclusion: 1. The early theories of matter were purely based on logic. 2. Early philosophers have no methods or instrument to prove or disproved their theories. 3. As time goes by, new experimental methods, new scientific methods flourished, and new modern instruments discovered, scientists now come to agree, based on much experimental evidence, that matter is indeed made up of ATOM. 4. The beliefs that atoms were indestructible, or indivisible was now disproved when scientists discovered the existence of subatomic particles. At present, scientists were now able to characterize the subatomic particles of matter, that brought the growth of new fields of science and technology that continues to progress in the next coming years.