General Chemistry Ch. 2 Notes PDF

GENERAL CHEMISTRY Ch:2 2.5, 2.6, 2.7, 2.8 Dr. AREEJ ALGHOUL  2.5: The Modern View of Atomic Structure: The simplest view of the atom is consists of:  a. A tiny nucleus:  It contain protons with + ve charge and neutrons with no charge.  b. an electrons move around the nucleus...

GENERAL CHEMISTRY Ch:2 2.5, 2.6, 2.7, 2.8 Dr. AREEJ ALGHOUL  2.5: The Modern View of Atomic Structure: The simplest view of the atom is consists of:  a. A tiny nucleus:  It contain protons with + ve charge and neutrons with no charge.  b. an electrons move around the nucleus. Note: In neutral atom:  # of electrons = # of protons Isotopes: The isotopes: atoms with the same number of protons but different numbers of neutrons. For example: sodium atoms have two isotopes. Both have 11 protons and 11 electrons, but they differ in the number of neutrons in their nuclei.  Q: Write the symbol for the atom that has an atomic number of 9 and a mass number of 19. How many electrons and how many neutrons does this atom have? The atomic number 9 means the atom has 9 protons. This element is called fluorine, symbolized by F. The atom is represented a  2.6: Molecules and Ions The chemical bonds: are the forces that hold atoms together in compounds. Types of chemical bonds: 1. Covalent bonds. 2. Ionic bonds. 1. Covalent bonds. atoms can form bonds is by sharing electrons. The resulting collection of atoms is called a molecule. Molecules can be represented in several ways. a. chemical formula ( the simplest method) b. structural formula (the individual bonds are shown) structural formula Structural formulas may or may not indicate the actual shape of the molecule. The molecules can be represented in several ways. The structural formula. The space-filling model: which shows the relative sizes of the atoms and thr relative orientation in the molecule. The ball-and-stick models are also used to represent molecules.  For CH4 molecule: (a)The structural formula. (b) Space-filling model. (c) Ball-and stick model. 2. Ionic bonds: An ion is an atom or group of atoms that has a net charge (positive or negative ). An example of an ionic compound is the table salt (NaCl), which forms when neutral chlorine and sodium react. one electron is lost from Na (11 protons and 11 electrons), to form Na+ (11 protons and 10 electrons). one chlorine (17 protons and 17 electrons) is accept the electron to form a negative charge ion Cl- (17 protons and 18 electrons) A positive ion is called cation. A negative ion is called anion. Because anions and cations have opposite charges, they attract each other. This force of attraction between oppositely charged ions is called ionic bonding. 2.7: An Introduction to the Periodic Table  The Periodic Table The number shown above each symbol is the atomic number.  Notes: Metals tend to form positive ions. Nonmetals tend to form negative ions. Elements in the same vertical column in the periodic table form a group (or family ) and generally have similar properties. The horizontal rows of elements in the periodic table are called periods. Horizontal row 1 is called the first period (it contains H and He); row 2 is called the second period (elements Li through Ne); and so on 2.8: Naming Simple Compounds In early chemists there was no system for naming compounds. common names were used, such as:  Sugar  Epsom salts.  Milk. As chemistry grew, nearly 5 million chemical compounds are currently known. Memorizing common names for these compounds would be an impossible task.  To solve this problem, we will begin with the systems for naming inorganic binary compounds. Binary compounds: are compounds composed of two elements We will consider both ionic and covalent compounds. Ionic compounds: is formed between metal and nonmetal Binary Ionic Compounds (Type I) Binary ionic compounds contain a positive ion (cation) always written first in the formula and a negative ion (anion). For example Binary Ionic Compounds (Type II) Metal with nonmetal The metals form more than one type of positive ion. The charge on the metal ion must be specified, using Roman numeral to indicate the charge of the cation. Roman numeral (I, II, III, IV, V, VI, VII, VIII, IX, X, ……..) The common cations(type I and type II) and anions Type II *Note mercury(I) ions always occur bound together to form Hg2+2 ions. These are transition metals, they form only one type of ion, and a Roman numeral is not used Ionic Compounds with Polyatomic Ion Oxyanions Oxyanions: are anions contain an element with different numbers of oxygen atoms. If there are two members in such a series: the smaller number of oxygen atoms ends in -ite the larger number of oxygen atoms ends in -ate Ex. sulfite (SO3)-2 sulfate (SO4)-2. Oxyanions If more than two oxyanions in the series, the following prefixes used to the name: hypo- (less than) per- (more than) Q:. Give the systematic name for each of the following compounds: a. Na2SO4 b. KH2PO4 c. Fe(NO3)3 d. Mn(OH)2 e. Na2SO3 f. Na2CO3 Answer: a. Na2SO4 Sodium sulfate b. KH2PO4 Potassium dihydrogen phosphate c. Fe(NO3)3 Iron(III) nnitrate (Type II must contain a Roman umeral) d. Mn(OH)2 Manganese(II) hydroxide (Type II must contain a Roman numeral) e. Na2SO3 Sodium sulfite f. Na2CO3 Sodium carbonate  Q: Given the following systematic names, write the formula for each compound: a. Sodium hydrogen carbonate b. Cesium perchlorate c. Sodium hypochlorite d. Sodium selenite e. Potassium bromate Answer: Name Formula a. Sodium hydrogen NaHCO3 OR sodium bicarbonate. b. Cesium perchlorate CsClO4 c. Sodium hypochlorite NaOCl d. Sodium selenate Na2SeO4 ( Se is named in the same way as S they are in the same group) e. Potassium bromate KBrO3 ( Br is named in the same way as Cl, they are in the same group). 2: Covalent Compounds (Type III) Binary Covalent Compounds (Type III) They are formed between two nonmetals (nonmetal+ nonmetal) They are named very similarly to binary ionic compounds (Type I) The first element in the formula is named first, using the full element name. The second element is named as if it were an anion. Prefixes are used to denote the numbers of atoms present. **** NOTE **** The prefix mono- is never used for naming the first element. Ex: CO is called carbon monoxide, not monocarbon monoxide  Ex: N2O Dinitrogen monoxide NO Nitrogen monoxide NO2 Nitrogen dioxide N2O3 Dinitrogen trioxide N2O4 Dinitrogen tetroxide N2O5 Dinitrogen pentoxide We often drop the final o or a of the prefix, when the element begins with a vowel.  Common name: Some compounds are always referred to by their common names (the systematic are never used). For examples: Water H2O  Ammonia NH3 Hydrogen peroxide H2O2 Q: Q1. Name each of the following compounds: a. PCl5 b. PCl3 c. SO2 Q2. From the following systematic names, write the formula for each compound: a. Sulfur hexafluoride b. Sulfur trioxide c. Carbon dioxide Solution Answers 1. Formula Name a. PCl5 Phosphorus pentachloride b. PCl3 Phosphorus trichloride c. SO2 Sulfur dioxide 2. Name Formula a. Sulfur hexafluoride SF6 b. Sulfur trioxide SO3 c. Carbon dioxide CO2 Q: Give the systematic name for each of the following compounds: a. P4O10 b. Nb2O5 c. Li2O2 d. Ti(NO3)4 a. P4O10 Tetraphosphorus (Binary covalent compound (Type III)) b. Nb2O5 Niobium(V) oxide (Type II binary compound and Nb is a transition metal and requires a Roman numeral) c. Li2O2 Lithium peroxide (Type I binary compound, O2-2 (peroxide) ions) d. Ti(NO3)4 Titanium(IV) nitrate Ionic compound contains the Ti+4 transition metal (requires a Roman numeral) and NO-3 polyatomic ions. Q: Q. Given the following systematic names, write the formula for each compound: a. Vanadium(V) fluoride b. Dioxygen difluoride c. Rubidium peroxide d. Gallium oxide Answer: Name Chemical Formula formula a. Vanadium(V) fluoride VF5 b. Dioxygen difluoride O 2F2 c. Rubidium peroxide Rb2O2 d. Gallium oxide Ga2O3 Acids Compounds that when dissolved in water, produce free H+ ions (protons). The rules for naming acids. An acid is a molecule in which one or more H+ ions are attached to an anion. 1. If the anion does not contain oxygen and the anion ends in -ide, the acid is named with the prefix hydro- and the suffix -ic. HCl hydrochloric acid HCN hydrocyanic acid H2S hydrosulfuric acid Naming of acids 2. If the anion contain oxygen (oxyanion) -ate -ic and -ite -ite For example, H2SO4 which contains sulfate anion, is named as sulfuric acid H2SO3 which contains sulfite is named as sulfurous acid HNO2 which contains nitrite is named nitrous acid. HNO3 which contains nitrate is named nitric acid. Naming of acids Acid Anion Name HClO4 Perchlorate Perchloric acid HClO3 Chlorate Chloric acid HClO2 Chlorite Chlorous acid HClO Hypochlorite Hypochlorous acid