M l Molecules l and dR Reactions ti Chapter 15 15 17 click here to get 9 page to print Electron dot structure pattern Ionic Bonds Electrical force of attraction between oppositely charged ions Ionic Bond Ratios Compounds form in ratios to neutralize charges Molecular Ions H H Water O H H Hydronium ion H3O Hydrogen ion Typically formed by the loss or gain of a hydrogen ion H Groups of atoms forming ions Molecular ions Bonds B d within ithi group are covalent l t Metallic Bonds Nucleus of metal atoms only weakly hold outer t electrons l t Weak attraction allows the electrons to move from one atom to another quite freely Metallic Properties Mobility of electrons results in many properties of metals Conductive Conductive electrons electrons move freely Shiny electrons vibrate and reflect light Malleable can move with respect to one another without breaking because electrons in constant motion Alloys electrons shared between unlike types yp of metal atoms Metallic Alloys An alloy is a mixture of metallic elements Metal Ores Few metals naturally occur as elements Gold copper pp mercuryy Most occur as oxides and sulfides Ionic I i compounds d Concentrations of these are ORE Covalent Bonds Atoms are held together by their mutual attraction for shared electrons There are two electrons within a single covalent bond Covalent Bond Diagrams The covalent bond is represented using a straight g line F F F F Covalent Water The number of covalent bonds an atom can form equals its number of unpaired valence electrons Covalent Ammonia The number of covalent bonds an atom can form equals q its number of unpaired p valence electrons Covalent Methane The number of covalent bonds an atom can form equals q its number of unpaired p valence electrons Multiple covalent bonds are possible if atom has more than one unpaired p valence electron Nonpolar Covalent Bonds Electrons are shared evenly when the two atoms are the same element Polar Covalent Bonds Shared unevenly when the bonded atoms are different elements Polar covalent bonds Closer together on the periodic table table less polar bond Further apart on the periodic table more polar bond Molecules are called dipoles Ionic bonds are extremely polar but not covalent Molecular Polarity Molecular Attractions Electrical attractions between molecules that does not result in bonding g Ions Polar molecules Non polar molecules Water and salt Ions of NaCl attract dipole of water Ion dipole attraction Ion dipole Water and water Dipole Dipole dipole attraction Dipoles ofdipole water attract one another Chemical Equations C O2 CO2 C s O2 g CO2 g Reactants on left left products on right Each are balanced because same number of atoms of reactants as products Some equations show the phase of the substances also solid liquid gas Balancing Chemical Equations Molecules of reactants and products shown Cannot change the molecule Can change how many of them Cannot add or delete reactants or products Balanced Balanced equal equal number of same atoms on each side Water balancing Balancing Tips Never change the molecular formula of reactants or products p Count atoms in reactant and products Always Al add dd whole h l molecules l l nott parts t Sta Startt by ba balancing a c g ato atoms s in co compounds pou ds Save element reactants or products for l t t make last to k up any imbalance i b l Rusting of Iron Fe O2 Fe2O3 not balanced start with oxygen Fe 3 O2 2 Fe2O3 next do iron 4 Fe 3 O2 2 Fe2O3 Combustion of propane C3H8 O2 CO2 H2O fix hydrogen first it s first it s in two compounds C3H8 O2 CO2 4 H2O need more carbon product C3H8 O2 3 CO2 4 H2O Do oxygen last because it is single C3H8 5 O2 3 CO2 4 H2O Volume Relationships Equal volumes of gases at the same temperature p and p pressure have the same number of molecules Gases react in small whole number quantities Avogadro s hypothesis chemicals react in consistent small whole number ratios Avogadro s Avogadro s hypothesis Combustion of propane C3H8 5 O2 3 CO2 4 H2O What volume of oxygen is needed to burn 0 5 L off propane 0 5 Ratio at o of o Oxygen O yge molecules o ecu es to p propane opa e molecules is 5 1 0 5 0 5 L x 5 L O2 25LO 2 5 Oxygen 1 L Propane p
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