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Chemical Bonds, Names and Formulas. Unit # 6. Big Ideas. OBJECTIVES: Distinguish between ionic and molecular compounds. Distinguish between ionic, covalent and metallic bonds Define cation and anion, and relate them to metal and nonmetal. Name molecules and compounds. What is a bond?.
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Chemical Bonds, Names and Formulas Unit # 6
Big Ideas • OBJECTIVES: • Distinguish between ionic and molecular compounds. • Distinguish between ionic, covalent and metallic bonds • Define cation and anion, and relate them to metal and nonmetal. • Name molecules and compounds
What is a bond? • The valence electron of one atom is attracted to the nucleus of another atom • Reasons Why? • Mutual attraction • To achieve a full valence shell • To have lower Kinetic Energy
Covalent Bonds • When a pair of electrons are “shared” between two atoms • This will occur between atoms that have similar electronegativity values • Non-metal bonded to non-metal
Covalent Bonds • Single bond – one pair of electrons are shared (2 electrons) • Double bond – two pairs of electrons are shared (4 electrons) • Triple bond – three pairs of electrons are shared (6 electrons)
Ionic Bonds • An unequal sharing of a pair of electrons between atoms • Between a metal and a non-metal • We usually say “ the metal will give up the electron and the non-metal will take the electron • Atoms that have a electronegativity difference higher than 1.7
Metallic Bonds • Bonds between 2 metals • Both metals will give up electrons and then share the “sea of electrons”
Determine the bond type • H2O • HCl • NaCl • KCr • KBr
Determine the bond type • H2O covalent • HCl covalent • NaCl ionic • KCr metallic • KBr Ionic
Atoms and ions • Atoms are electrically neutral. • Same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge (positive or negative) • Different numbers of protons and electrons. • Only electrons can move. • Gain or lose electrons.
Anion • A negative ion. • Has gained electrons. • Nonmetals can gain electrons. • Charge is written as a superscript on the right. Has gained one electron (-ide is new ending= fluoride) F1- O2- Gained two electrons (oxide)
Cations • Positive ions. • Formed by losing electrons. • More protons than electrons. • Metals can lose electrons Has lost one electron (no name change for positive ions) K1+ Ca2+ Has lost two electrons
Back to New Material Now let’s bond the old material to the new material
Two types of Compounds Ionic and molecular
Ionic Compounds • Ionic compounds- from joining metal and nonmetal - they are electrically neutral • Metal and polyatomic ion • Ionic Bonds
Ionic Compounds • This formula represents not a molecule, but a formula unit • The smallest whole number ratio of atoms in an ionic compound. • Ions surround each other so you can’t say which is hooked to which.
Molecules and Molecular Compounds Molecular compounds • Made of molecules. • Made by joining nonmetal atoms together into molecules. • Covalent bonds
Molecules and Molecular Compounds • Molecule- smallest electrically neutral unit, still has properties of the substance • Made from only nonmetals • Can be from one element- O2 • Can make a compound- CO2
Two Types of Compounds Ionic Molecular Smallest piece Formula Unit Molecule Types of elements Metal and Nonmetal Nonmetals Solid, liquid or gas State solid Bond Type Ionic Covalent
Chemical Formulas • Shows the kind and number of atoms in the smallest piece of a substance. • Molecular formula- number and kinds of atoms in a molecule. • CO2 • C6H12O6
Chemical Formulas • More than one atom? –use a subscript (H2O) • There are 7 diatomic elements • Hydrogen (H2), Nitrogen (N2), Oxygen (O2), Fluorine (F2), Chlorine (Cl2), Bromine (Br2), and Iodine (I2) • Remember: “Br I N Cl H O F”
Charges on ions • Elements in the same group have similar properties. • Including the charge when they are ions • Remember Group 1 forms +1 ions
1+ 2+ 3+ 3- 2- 1-
What about the others? • Many transition metals have more than one common ionic charge • We use roman numerals in naming
More Big ideas • OBJECTIVES: • Name ions based on their oxidation state • Define a polyatomic ion, and give the names and formulas of the most common polyatomic ions.
Naming ions • Two methods if more than one charge is possible: • 1. Stock system – uses roman numerals in parenthesis to indicate the numerical value • 2. Classical method – uses root word with suffixes (-ous, -ic) • Does not give true value
Naming ions • We will use the Stock system. • Cation- if the charge is always the same (Group A) just write the name of the metal. • Transition metals can have more than one type of charge. • Indicate the charge with roman numerals in parenthesis
Name these • Na1+ • Ca2+ • Al3+ • Fe3+ • Fe2+ • Pb2+ • Li1+
Write Formulas for these • Potassium ion • Magnesium ion • Copper (II) ion • Chromium (VI) ion • Barium ion • Mercury (II) ion
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorine
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorin
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluori
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluor
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluori
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluorid
Naming Anions • Anions are always the same charge • Change the element ending to – ide • F1- Fluoride
Name these • Cl1- • N3- • Br1- • O2- • Ga3+
Write these • Sulfide ion • iodide ion • phosphide ion • Strontium ion
Exceptions: • Some of the transition metals have only one ionic charge: • Do not use roman numerals for these: • Silver is always 1+ (Ag1+) • Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)
Polyatomic ions • Groups of atoms that stay together and have a charge. • Acetate C2H3O21- • Nitrate NO31- • Nitrite NO21- • Hydroxide OH1- and Cyanide CN1- • Permanganate MnO41-
Sulfate SO42- Sulfite SO32- Carbonate CO32- Chromate CrO42- Dichromate Cr2O72- Phosphate PO43- Phosphite PO33- Ammonium NH41+ Polyatomic ions
Big Idea • OBJECTIVES: • Apply the rules for naming and writing formulas for binary ionic and ternary ionic compounds.
Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • To write the names, just name the two ions. • Easy with Representative elements (which are Group A elements) • NaCl = Na1+Cl1- = sodium chloride • MgBr2 = Mg2+Br1-= magnesium bromide
Naming Binary Ionic Compounds • The problem comes with the transition metals. • Need to figure out their charges. • The compound must be neutral. • same number of + and – charges. • Use the anion to determine the charge on the positive ion.
Naming Binary Ionic Compounds • Write the name of CuO • Need the charge of Cu • O is 2- • copper must be 2+ • Copper (II) oxide • Name CoCl3 • Cl is 1- and there are three of them = 3- • Co must be 3+ Cobalt (III) chloride
Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is 2-, the Cu2 must be 2+, so each one is 1+. • copper (I) sulfide • Fe2O3 • Each O is 2- 3 x -2 = -6 • 2 Fe must = 6+, so each is 3+. • iron (III) oxide
Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se
Ternary Ionic Compounds • These will have polyatomic ions • At least three elements • name the ions • NaNO3 • CaSO4 • CuSO3 • (NH4)2O
Ternary Ionic Compounds • LiCN • Fe(OH)3 • (NH4)2CO3 • NiPO4