4.1 Defining the Atom Overview cannot be seen w/ naked eye def. smallest particle of an element that retains its identity in a chemical reaction Democritus’ Atomic Philosophy Democritus (460 BC- 370 BC) was a Greek philosopher first suggested the existence of atoms said they were indivisible and indestructible did not explain chemical behavior did not use scientific method John Dalton (1766-1844) English chemist schoolteacher used experimental methods he transformed Democritus’ ideas
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Mastering Concepts 2.1 1. Which chemical elements do organisms require in large amounts? Carbon‚ oxygen‚ hydrogen‚ nitrogen‚ sulfur‚ and phosphorus are the chemical elements that organisms require in large amounts. 2. Where in an atom are protons‚ neutrons‚ and electrons located? An atom’s protons and neutrons are in its nucleus. A cloud of electrons surrounds the nucleus. 3. What does an element’s atomic number indicate? An atom’s atomic number indicates the number of protons in its nucleus
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block an atom (meaning not divisible). Democritus believed that everything around us such as metal‚ water‚ and wood were atoms‚ but Dalton believed and proved that it could be more basic than that. He started thinking of compounds such as water‚ salt‚ or wood; that they could be a number of atoms combined to make that product. He also believed that atoms such as carbon‚ gold‚ and hydrogen could not be broken down. Dalton made some rules according to his theory: 1. All elements are made of atoms. 2.
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Module 16 Notes Reduction/Oxidation Reactions • Oxidation number: The charge that an atom in a molecule would develop if the most electronegative atoms in the molecule took the shared electrons from the less electronegative atoms. • Oxidation numbers are not real; they are only based on assumptions. They are useful bookkeeping tools though‚ and can help us keep track of electrons during a reaction. • The sum of all oxidation numbers in a molecule must equal the charge of that molecule. • Rules
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electrons of two different atoms. This attraction results in the two atoms binding together. An ionic bond‚ also called an electron-transfer bond‚ is a type of chemical bond that is a result of the electromagnetic attraction between ions of opposite charges‚ i.e.‚ a cation (a positively charged ion) and an anion (a negatively charged ion). An ion is an atom or group of atoms that has acquired an electrical charge due to the loss or gain of electrons. In an ionic bond‚ an atom gives or receives electrons
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acknowledge the reason atoms react with one another in the first place. Each element has a certain number of valence electrons‚ an example being Sodium having one valence electron. When elements react they are trying to get a full shell of eight valence electrons by either giving away‚ taking in‚ or sharing valence electrons. The best way I can think to describe how atoms decide which method to do is that atoms have their
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Atomic structure: scientists 1. Democritus: 1st person to think of atom (500 BCE)- philosopher Atom is the smallest piece of an element that has same properties as the element. 2. Lavisier: Law of conservation of mass/ matter • Mass can’t be created or destroy; same amount of stuff 3. Joseph Proust: Law of constant composition (law of definite Proportions) • A compound is always made of the same elements in the same ratio. 4. John Dalton: English school teacher who derived the atomic theory
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Lewis Structures and the Shapes of Molecules Pre-Lab Assignments: To be assigned by your lab instructor. Student Learning Outcomes: Learn how to draw Lewis structures. Learn how to draw Lewis structures for atoms which violate the octet rule. Learn how to use Lewis structures and VSEPR and to predict the shapes of molecules. Learn how to use the shape of a molecule to predict whether or not it is polar. Experimental Goals: The purpose of this lab is to learn how to draw Lewis
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UNIVERSITY OF THE GAMBIA LECTURE NOTES COURSE: PRINCIPLES OF CHEMISTRY II (ORGANIC CHEMISTRY) CODE: CHM 161 2ND SEMESTER SESSION: 2012/2013 LECTURER: ANTHONY F. ADJIVON UNIT 1 INTRODUCTION Organic chemistry started as the chemistry of life‚ when that was thought to be different from the chemistry in the laboratory. Then it became the chemistry of carbon compounds‚ especially those found in coal. Now it is both. It is the chemistry of the compounds of carbon along with other elements
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like sodium chloride and water play important roles in living things‚ most compounds found in organisms are more complex‚ containing at least three or four elements. Concept 4.2 Chemical properties are based on the structure of atoms. Different elements have different properties. Some are solid metal at room temperature‚ some are invisible gases‚ some elements readily react with other elements‚ whiles others hardly react at all. These properties affect the roles that
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