Chem 111 Ch.2
Chem 111 Ch.2 Chem 111
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This 3 page Class Notes was uploaded by Kim Notetaker on Sunday September 4, 2016. The Class Notes belongs to Chem 111 at California State University Chico taught by in Fall 2016. Since its upload, it has received 5 views. For similar materials see General Chemistry in Science at California State University Chico.
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Date Created: 09/04/16
Chapter 2: Atoms, Molecules and Moles Atomic Representations Types: Microscopic Macroscopic Symbolic Semimetal (metalloids): lye along he zigzag line in the periodic table Column 1A: Alkali metals they react by water Column 2A: Alkaline are earth metals Column 7A: Halogens are colorful Column 8A: Noble Gases don’t react of interact with other chemicals Intensive Properties vs. Extensive Properties Intensive properties are independent of size Color, combustibility, hardness, melting point…etc. Extensive Properties depend on size (size matters) Mass, volume, weight…etc. Physical Properties vs. Chemical Properties Physical Properties are not changing the chemical makeup Color, hardness, mass, volume…etc. Chemical Properties are changing the chemical makeup Combustibility, reactivity with acid, tendency to corrode…etc. Law of Conservation of mass: Mass is neither created nor destroyed in chemical reaction Laws of Definite properties: Different samples of a pure chemical substance always contain the same proportions of elements by mass Law of Multiple properties: Elements can combine in different ways to form different substances whose mass ratios are have a small whole number multiples of each other. Atomic Structure: Protons & Neutrons The mass of 1 atom of carbon 12 is defined to be 12 amu 1u=1.660539x10 to the 24 g The mass of the atom is primarily in the nucleus The charge of the proton is opposite in sign but equal to that of the electron Electrons are 2000 times smaller than an atom Atomic number (z): Number of protons in an atom’s nucleus number of electrons around an atoms nucleus in a neutral atom Mass number (A): number of protons (Z) + number of neutrons # of n=AZ atomic# (z)= # of p+ mass#= # of p+ + # of neutrons Isotope: Atoms with identical atomic numbers but different mass number Carbon 12: Mass# 12 atomic# 6 p:6 e:6 n:6 Carbon 14: Mass# 14 atomic# 6 p:6 e:6 n:8 Atomic Masses & The Mole: A collective unite 1dozen = 12 things 1 mole = 6.022x 10 to the 23 things Atoms molecules, particles…etc. Avogadro’s number (Na)= one mole of any substances contains 6.022x 10 to the 23 rd formula unit Molar mass: the mass in grams of one mole of any element it is numerically equivalent to its atomic mass. rd 1 mole of formula units = 6.022x10 to the 23 formula units 1 mole of element = atomic mass of element Chemical compounds: a pure substance that is composed when two different element combine in a specific way to create a new material with properties completely unlike those of its constituent elements Molecule and Covalent Bonds Covalent Bond: results when two atoms share several (usually two) electrons. Typically a nonmetal bonded to a nonmetal Molecule: the unit of matter that results when two of more atoms are joined by covalent bonds Diatomic Molecules: are composed of two atoms of the same element; they are: H2 N2 O2 F2 Cl2 Br2 I2 Ions and Ionic Bonds Ionic Bonds: transfer of one or more electrons Strong electrical attraction between charged particles Typically a metal bonded to a nonmetal Ions: A charged particle Cation: a positively charged particle; one or more e fewer than neutral. Metals tend to form cations Anion: a negatively charged particle one or more e more than neutral. Nonmetals tend to form anions Ionic Compound: a neutral compound in which the total # of positive charges must equal the total number of negative charges
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