Chemical Bonding Test Study Guide Salt: common name for ionic compounds Vocabulary: Lewis Dot Structure: Diagrams showing the number of paired and unpaired electrons in a compound Alloy: A mixture of metals that acts like a metallic bond Anion: negatively charged particle VSEPR: Valence Shell Electron Pair Repulsion Model Cation: positively charged particle Content: Chemical Bond: A force that holds atoms together in a compound Compare and contrast ionic, covalent, and metallic bonding: Ionic-transferring electrons; covalent-sharing electrons; metallic-bonding with the “sea” of electrons Conductivity: The ability to allow heat or electricity to pass through an object Covalent Bond: A chemical bond created by the sharing of electrons How can you tell from a chemical formula if a compound is ionic or covalent? Ionics will typically be a metal and a nonmetal; covalent will be multiple nonmetals, only Ductility: The ability to be drawn into wire Electronegativity: An atom’s ability to attract electrons Ion: A charge particle Ionic Bond: A chemical bond created by the attraction between cations and anions when electrons are exchanged List the properties of an ionic compound (salts) and describe how they form: They from by transferring electrons; they have strong bonds, crystalline structure, high melting points, are brittle, and conduct electricity in solution List the properties of covalent compounds (molecules) and describe how they form: They form from sharing electrons; they have weak bonds, low melting points, are poor conductors Luster: shininess Malleability: Ability to change shape without breaking Metallic Bond: A chemical bond formed when the sea of delocalized electrons Oxidation Number: The charge an atom has when it becomes an ion Polar Covalent Bond: A covalent bond where electrons are not shared equally Polyatomic Ion: An ion containing multiple atoms covalently bonded List the properties of metallic bonds and describe how they form: Form by bonding with the “sea” of electrons around other metals; they are lustrous, ductile, malleable, high melting points, excellent conductors List the 7 diatomic molecules and describe why they are called diatomic: They are diatomic because they cannot exist alone in nature, so they must bond with another atom of the same element. H2, N2, O2, F2, Cl2, Br2, I2 Describe a linear molecule and draw a picture of one: 2 shared pairs, 0 unshared pairs C Describe a bent molecule and draw a picture of one: 2 shared pairs, 2 unshared pairs Tetrahedral, nonpolar Chemical Formulas and Names: Describe the process for writing a chemical formula for an ionic bond: Find the oxidation number for each ion involved, criss-cross the oxidation numbers, reduce if necessary Describe a trigonal planar molecule and draw a picture of one: 3 shared pairs, 0 unshared pairs What do you have to do with polyatomic ions when writing chemical formulas? Put them in parenthesis and do not change their subscripts or names What must you do to the end of an elements name when it is the second element in a compound? Change it to -ide Describe a trigonal pyramidal molecule and draw a picture of one: 3 shared pairs, 1 unshared pair Describe a tetrahedral molecule and draw a picture of one: 4 shared pairs, 0 unshared pairs Draw the Lewis dot structure for the following and determine their shapes and polarity (Electronegativities: N = 3.0, F = 4.0, C = 2.5, Br = 2.8) a.) Nitrogen trifluoride trigonal pyramidal, polar b.) Carbon tetrabromide Which elements require the stock system (Roman Numerals in parenthesis) for naming them? What does this number represent? Transition metals, represents the oxidation number Which type of bond(s) require prefixes for naming the compound? Covalent, only Write the prefixes used for 1-10: 1- mono 2- di 3- tri 4- tetra 5- penta 6- hexa 7- hepta 8- octa 9- nona 10- deca Determine the most likely oxidation number for each of the following elements: Iodine: -1 Lithium: +1 Nitrogen: -3 Sulfur: -2 Titanium (II): +2 Aluminum: +3 Barium: +2 Write the chemical formulas for the following compounds: a.) Magnesium chloride MgCl2 b.) Potassium dichromate K2Cr2O7 c.) Chromium (III) oxide Cr2O3 d.) dinitrogen trioxide N2O3 e.) hexaboron monosilicide B6Si Name the following compounds: a.)Li3N Lithium Nitride b.)K3PO4 Potassium Phosphate c.)NiCl3 Nickel (III) Chloride d.)P4S5 Tetraphosphorus pentasulfide e.) Si2Br6 Disilicon hexabromide Explain why atoms seek out other atoms for chemical bonding: In order to achieve electron stability (full valence energy level), like the noble gases Compare and contrast single, double, and triple bonds: Single bonds contain one shared pair of electrons, are weak, and are the greatest in length Double bonds contain 2 shared pairs of electrons and have a strength and length between single and triple bonds Triple bonds contain 3 shared pairs of electrons, are very strong, and are the shortest in length Which of the 7 diatomic molecules contains the strongest bonds? How do you know? N2, because it contains triple bonds