Chemistry Lesson 2 PDF

EXERCISE (LESSON 1): 1. At what temperature does the numerical reading on a Celsius thermometer be equal to the reading on a Fahrenheit thermometer? 2. Convert: 12 x 10^6 lbf/sq. ft to MPa 3. What is the mass of a rectangular piece of copper 2.44 in by 1.14 in...

EXERCISE (LESSON 1): 1. At what temperature does the numerical reading on a Celsius thermometer be equal to the reading on a Fahrenheit thermometer? 2. Convert: 12 x 10^6 lbf/sq. ft to MPa 3. What is the mass of a rectangular piece of copper 2.44 in by 1.14 in by 1.89 in, if the density of copper is 8.92 g/cubic cm. EXERCISE (LESSON 1): 1. Find the mass of oil (specific gravity = 0.7) If there are 325 ml of oil present. 2. Power is defined as the amount of work done over a given time. If a person pushes a crate at 152 N, 3 m in 15 seconds. 3. Angstrom is a unit of length (10^10 m = 1 Å). Convert 3 angstroms to nanometers.  CHEMISTRY FOR ENGINEERS LESSON 2: A MOLECULAR VIEW OF MATTER PREPARED BY: ENGR. PATRICIA EMMANUELLE D. RAGANIT  CONTENT 01 ATOMIC THEORY 02 ATOMIC NUMBER, MASS NUMBER AND ISOTOPES 03 MOLECULES 04 IONS ATOMS Basic building blocks of matter, exist on a nanoscale Comes from the Greek word atomos which means indivisible or uncuttable particles smallest particle of an element that maintains its chemical identities ATOMIC THEORY Democritus (470 - 400 BC) stated that all matter is composed of tiny, discrete, indivisible particles based on philosophical speculation ATOMIC THEORY John Dalton (1766-1844) published the first “modern” ideas about the existence and nature of atoms (1808) based on reproducible experimental results Father of modern atomic theory Dalton’s Atomic Theory 1. An element is composed of extremely small, indivisible particles called atoms 2. All atoms of a given element have an identical properties that differ from those of other elements. ATOMIC THEORY Dalton’s Atomic Theory 3. Atoms cannot be created, destroyed, or transformed into atoms of another element. 4. Compounds are formed when atoms of different elements combine with one another in small whole- number ratios. 5. The relative numbers are kinds of atoms are constant in a given compound  RELEVANT LAWS LAW OF DEFINITE PROPORTIONS (Joseph Proust) states that different samples of the same compound contain only its constituent element in the same proportion  RELEVANT LAWS LAW OF MULTIPLE PROPORTIONS if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other elements are in the form of ratios of whole small numbers ATOMIC THEORY It was later found out that atoms are comprised of three fundamental particles namely: electrons, protons and neutrons ELECTRON (Plum-pudding model) J.J THOMSON discovered electrons in 1897 using a series of experiments using cathode rays. He called the particles ‘corpuscles’ which is later on renamed as ‘electrons’ proposed the plum-pudding model in 1904 in which the structure of the atom is compared to a blueberry muffin, with electrons embedded in a jelly-like sphere of positive charge. ROBERT MILLIKAN measured the mass of electrons (1923 Nobel Prize in Physics) ATOMIC THEORY CATHODE RAY TUBE EXPERIMENT ATOMIC THEORY PROTON ERNEST RUTHERFORD performed the Gold Foil Experiment in 1911 together with Hans Geiger and Ernest Marden. The experimentation mainly led to the the discovery of the ff: 1. Most of the volume of an atom is empty (Approximately 99.9999999999996%) 2. Most of the mass of the atom is concentrated in a dense, positively charged nucleus 3. Electrons are present in the space surrounding the nucleus. ATOMIC THEORY PROTON 5. Proton has the opposite charge of the electron 6. Protons can’t go out of the nucleus because of the strong nuclear force 7. The mass of proton 1836 (approximately 1840) times of the mass of electron Strong Nuclear force - Binds protons and neutrons (and other hadrons) together within atomic nuclei, overcoming the electrostatic repulsion between protons. Weak Nuclear force - Responsible for processes such as beta decay, where a neutron decays into a proton, electron, and an antineutrino. ATOMIC THEORY GOLD FOIL EXPERIMENT ATOMIC THEORY PLANETARY MODEL NEILS BOHR also known as the Bohr model proposed in 1913, describes the atom as having a small, dense, positively charged nucleus at its center, composed of protons (and later understood to include neutrons) Electrons orbit the nucleus in fixed, circular paths called orbits or shells, with each orbit corresponding to a specific energy level. ATOMIC THEORY PLANETARY MODEL NEILS BOHR ATOMIC THEORY QUANTUM MODEL Erwin Schrödinger Describes electrons in terms of wave functions (ψ), which represent the probability density of finding electrons in different regions around the nucleus Electrons occupy discrete energy levels determined by solutions to the Schrödinger equation, reflecting the quantized nature of energy in atoms. Schrödinger Equation governs the behavior of these wave functions, accounting for both the particle-like and wave-like properties of electrons within the framework of quantum mechanics ATOMIC THEORY QUANTUM MODEL Erwin Schrödinger (1926) ATOMIC THEORY NEUTRON JAMES CHADWICK discovered neutrons through an experiment involving the bombardment of beryllium with alpha particles The experimentation mainly led to the the ff: 1. Chadwick observed that this radiation was not deflected by electric or magnetic fields, indicating that it was electrically neutral. 2. Found out that neutrons has almost the same mass as protons but with no electric charge. TABLE 2.1 MASS AND CHARGE OF SUBATOMIC PARTICLES Particle Mass Charge Electron Proton Neutron No charge ATOMIC THEORY SUMMARY ATOMIC NUMBER, MASS NUMBER AND ISOTOPES  ATOMIC NUMBER -Represents the number of protons in the nucleus of an atom. MASS NUMBER - The atomic mass, also known as the mass number, is the total number of protons and neutrons in an atom's nucleus. In a neutral atom, number of protons = number of electrons iSOTOPES - variants of a given element that have the same number of protons (same atomic number) but different numbers of neutrons, resulting in different atomic masses AVERAGE MASS Average mass of an element = = mass of isotopes = percent abundance of isotopes Note: Atomic mass is expressed in amu SAMPLE PROBLEMS 1. Determine the number of protons, neutrons and electrons of the following: 2. The two most prevalent isotopes of Cadmium has 66 neutrons and 64 neutrons, respectively. If Cadmium has 48 protons, write the symbols for the aforementioned isotopes. SAMPLE PROBLEMS 3. Copper, a metal known since ancient times, is used in electrical cables and pennies, among other things. The atomic masses of its two isotopes are 62.93 amu and 64.925 amu respectively. The first isotope is known to compose 56.89 % of the copper, calculate its average atomic mass MOLECULE MOLECULE the smallest particle of an element or compound that can have a stable independent existence. an aggregate of two or more atoms in a definite arrangement held together by chemical forces Diatomic molecules contains only two atoms Polyatomic molecules contains more than two atoms MOLECULE MOLECULE MOLECULE IONS IONS An ion is an atom or group of atoms that has a net positive or negative charge TYPES OF IONS 1. Cation - ion with a net positive charge 2. Anion - ion with a net negative charge 3. Monoatomic Ion - an ion that contains only one atom 4. Polyatomic Ion - an ion that contains more than one atom Potassium ion (K⁺) - Monoatomic Oxide ion (O²⁻) - Monoatomic Hydroxide ion (OH⁻) - Polyatomic Carbonate ion (CO₃²⁻) - Polyatomic Phosphate ion (PO₄³⁻) - Polyatomic IONS QUIZ #1: NEXT WEEK COVERAGE: LESSON 1 AND 2