Chem Chapter 4 Notes Textbook
Chem Chapter 4 Notes Textbook Chem 1301
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Popular in Chemistry
This 3 page Class Notes was uploaded by Kayra Reyes on Friday September 2, 2016. The Class Notes belongs to Chem 1301 at University of Houston taught by Roman S. Czernuszewicz in Fall 2015. Since its upload, it has received 87 views. For similar materials see Foundations of Chemistry in Chemistry at University of Houston.
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Date Created: 09/02/16
Chapter 4 of “Introductory Chemistry” by Zumdahl and Decoste, 7 /8 edition Law of Constant Composition: a given compound always has the same composition, regardless of where it comes from Ex: carbon dioxide is always 2.7g of oxygen per 1g of carbon Dalton’s Atomic Theory 1. “Elements are made of tiny particles called atoms” 2. “All atoms of a given element are identical” *Later corrected by Dalton to (#2): “All atoms of the same element contain the same number of protons and electrons, but atoms of a given element may have different numbers of neutrons” 3. “The atoms of a given element are different from those of any other element” 4. “Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms.” 5. “Atoms are indivisible in chemical processes. That is, atoms are not created or destroyed IN CHEMICAL REACTIONS. A chemical reaction simply changes the way the atoms are grouped together.” Compound: distinct substance composed of two or more elements Rules for Writing Formulas 1. Each atom present is represented by its element symbol 2. The number of each type of atom is indicated by a subscript written to the right of the element symbol. 3. When only one atom of a given type is present, the subscript 1 is not written Ex: (one atom of sulfur) SO 3 (3 atoms of oxygen) Atoms are made up of subatomic parts called electrons as well as protons, the positively charged particles Nuclear atom: an atom with a dense counter of positive charge Nucleus: contains particles in center of atom Neutron: a neutral particle, slightly larger than a proton Chemical Formula: expresses the type of atoms and the number of each type of each molecule of a given compound or unit Isotopes: atoms with the same number of protons but different number of neutrons Atomic Number: number of protons in a nucleus Mass Number: sum of the number of neutrons and protons in a nucleus Periodic Table: chart with all elements and specific details on them *ordered by increasing atomic number Groups: elements with similar chemical properties, lined vertically Alkali Metals: Alkali Earth Metals: Halogens: Noble Gases: Group1 Group 2 Group 7 Group 8 *Most of the elements are metals Physical Properties of Metals 1. Efficient conducting of heat and electricity 2. Malleability (they can be hammered into tiny sheets) 3. Ductility (they can be pulled into wires) 4. A lustrous (shiny) appearance Non-metals: small number of elements at upper right corner of table Metalloids: elements are near stair step line area, mixture of metals and nonmetal properties Diatomic Molecules: molecules made up of two atoms *like oxygen (02) or Nitrogen (N2) Allotropes: different forms of a given element Ion: a charged entity, a neutral atom- one or more electrons Cation: a positive ion made when one or more electrons are lost from a neutral atom Anion: negatively charged ion, when atom gains extra electron Ions are never formed by a changing number of protons Metals ALWAYS make positive ions Nonmetals ALWAYS make negative ions Most traditional metals make cations “Substance that contain ions can conduct an electric current only if the ions can move” THUS substance cannot be solid, must be melted Ionic Compounds: substance containing ions “Chemical compound MUST have a net charge of zero”