In-organic Chemistry Fall 2022 CHE1211, 1221, 1231 Lecture Notes PDF

In-organic Chemistry Fall 2022 CHE1211, 1221, 1231. Dr. Aliaa Abdel-Fattah Email: [email protected] Lec 2 Atomic Theory of Matter COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 1  Atomic Theory of Matter ▪ Atoms- the smallest partic...

In-organic Chemistry Fall 2022 CHE1211, 1221, 1231. Dr. Aliaa Abdel-Fattah Email: [email protected] Lec 2 Atomic Theory of Matter COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 1  Atomic Theory of Matter ▪ Atoms- the smallest particle of an element with all of the properties of that element. ▪ All matter is made of atoms. ▪ Atoms are the basic building blocks of matter. They make up everything around us; Your desk, the board, your body, everything is made of atoms! ▪ Atoms are too small to see without powerful microscopes. ▪ Element- a part of a substance not able to be separated into smaller substances by chemical means. ▪ Nucleus- the center of an atom that accounts for most of the atom’s mass. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 2  Surface of graphite as imaged by a scanning tunneling microscope COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 3 Atomic Structure There are two basic components in every atom: Electron Cloud Nucleus COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 4 Subatomic Particles Three subatomic particles make up every atom: Subatomic Particle Charge Location Proton Positive (+) Nucleus or “Core” Neutron No Charge (0) Nucleus or “Core” Electron Negative (-) Electron Cloud COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 5  Sub- Atomic Particles Protons (+) positively charged particles found in the nucleus of an atom. Neutrons (o) neutrally charged particles found in the nucleus of an atom. Electrons (-) negatively charged particles that revolve around the nucleus of an atom. Symbol for electrons (e-). COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 6 Subatomic Particles Electron Cloud: Electrons orbit the nucleus. Nucleus or “Core”: Protons and Neutrons are found in the nucleus. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 7 Atomic Theory Changes over time… COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 8 Atomic Theory Because we can not see atoms, we use models to teach and learn about atoms. The atomic theory has changed over time as new technologies have become available. Remember: Scientific knowledge builds on past research and experimentation. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 9 COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 10 Atomic Theory Timeline Scientist Information Model John All matter is made of atoms. Atoms Dalton are too small to see, indivisible and indestructible. All atoms of a given element are identical. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 11  Are Atoms really indivisible? Dalton reached his conclusions about atoms on the basis of evidence gained on a macroscopic level. As scientists developed more instrumentation capable of probing phenomena at a microscopic level, more about atoms was understood. Example: The color of the emitted light characterizes the element. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 12 John Dalton believed that: 1. Elements are composed of indivisible atoms. 2. The atoms of different elements have different masses and chemical properties. 3. Atoms are not created or destroyed during a chemical reaction, they're simply rearranged to form chemical compounds. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 13 Atomic Theory Timeline Scientist Information Model Discovered the negative electron, J.J Thompson and predicted that there also must be a positive particle to hold the electrons in place. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 14  Electrons J.J. Thompson showed that the cathode rays were in fact particles of NEGATIVE charge, the rays could be deflected by a magnetic field. The term ELECTRON was coined for the negative particles. Thompson also calculated the charge of each particle COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 15  Atomic Theory Timeline Scientist Information Model Ernest Discovered the nucleus of an atom and Rutherford named the positive particles in the nucleus “protons”. Concluded that electrons are scattered in empty space around the nucleus. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 16 COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 17 Atomic Theory Timeline Scientist Information Model Neutrons James Discovered that neutrons were also Chadwick located in the nucleus of an atoms and that they contain no charge. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 18 Atomic Theory Timeline Scientist Information Model Neils Concluded that electrons are Bohr located in planet-like orbits around the nucleus in certain energy levels. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 19  Scientist Information Model (Many Scientists!) Electrons do not orbit the The Modern Atomic Theory nucleus in neat planet-like orbits but move at high speeds in an electron cloud around the nucleus. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 20 MASS – unit typically used is an ATOMIC MASS UNIT (amu) 1 amu = 1.66054 x 10–24 g Particle Charge Mass (g) Mass (amu) Proton +1 1.6727x10-24 1.0073 Neutron Neutral 1.6750x10-24 1.0087 Electron -1 9.109x10-28 5.486 x 10-4 Note: LENGTH – ANGSTROM(Å) = 10-10m Typical atomic dimensions are 1 to 5 x10-10 m which corresponds to 1 to 5 Å. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 21  Relative Atomic Mass A relative scale has been developed to compare the relative masses of atoms. The ATOMIC MASS of an atom is its relative mass on this scale. Carbon- 12 ( 12 C) has been set as the standard and assigned a RELATIVE MASS of exactly 12. Relative atomic masses have no units since they are the ratio of two masses. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 22  Law of Conservation of Mass 1 7 7 5 - L AVO ISIER “ FAT H ER O F MO D ER N C H EM IST RY ” In every chemical operation an equal amount of matter exists before and after the operation. Mass is conserved, the total mass after the chemical operation must be the same as that before. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 23 Problem 1: Potassium chlorate (KClO3) decomposes to potassium chloride (KCl) and oxygen (O2) when heated. In one experiment 100.0 g of KClO3 generated 36.9g of O2 and 57.3 g of KCl. What mass of KClO3 remained unreacted? COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 24 Mass of KClO3 before reaction = mass of KCl + mass of O2 + mass of unreacted KClO3 100.0 g of KClO3 = 57.3 g KCl + 36.9g O2 + g unreacted KClO3 g unreacted KClO3 = 100.0 g - 57.3 g - 36.9 g = 5.8 g COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 25 Examples: Example 1. 7 grams of Hydrogen reacts with oxygen to 30 grams of water. Apply the law of conservation of mass to calculate how much oxygen is required. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 26 Example 2. 10 grams of Sodium Carbonate, 4.4 grams of Carbon dioxide and 5.6 grams of sodium oxide is produced. Prove that this reaction obeys the law of conservation of mass. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 27  H.W 1: 1. Are these sentences true or false? a) According to Thomson’s model of the atom, protons can be found all over the atom. b) Protons and electrons have fixed positions in the atom. c) The radius of the atom and the radius of the nucleus is the same. d) According to Rutherford’s model of the atom, electrons move around the nucleus of the atom as planets do around the Sun. e) Neutrons have no mass f) According to Bohr’s model of the atom, electrons behave like waves. COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 28 Thank You COPYRIGHT (C)A. ABDEL-FATAH, G. CHEMISTRY 2024 CHEG 29