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

Let’s Review some old concepts to tie this together

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.

F1- O2- 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)

K1+ Ca2+ Cations Positive ions. Formed by losing electrons. More protons than electrons. Metals can lose electrons K1+ Has lost one electron (no name change for positive ions) Ca2+ Has lost two electrons

Now let’s bond the old material to the new material 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 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-

Polyatomic ions Sulfate SO42- Sulfite SO32- Carbonate CO32- Chromate CrO42- Dichromate Cr2O72- Phosphate PO43- Phosphite PO33- Ammonium NH41+

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

Writing Formulas The charges have to add up to zero. Get charges on pieces. Cations from name on table. Anions from table or polyatomic. Balance the charges by adding subscripts. Put polyatomics in parenthesis.

Writing Formulas Write the formula for calcium chloride. Calcium is Ca2+ Chloride is Cl1- Ca2+ Cl1- would have a 1+ charge. Need another Cl1- Ca2+ Cl21- (use criss-cross method)

Write the formulas for these Lithium sulfide tin (II) oxide tin (IV) oxide Magnesium fluoride Copper (II) sulfate Iron (III) phosphide gallium nitrate Iron (III) sulfide

Write the formulas for these Ammonium chloride ammonium sulfide barium nitrate

Things to look for If cations have ( ), the number in parenthesis is their charge. If anions end in -ide they are probably off the periodic table (Monoatomic) If anion ends in -ate or -ite it is polyatomic

Section 6.5 Molecular Compounds and Acids OBJECTIVES: Apply the rules for naming and writing formulas for binary molecular compounds.

Section 6.5 Molecular Compounds and Acids OBJECTIVES: Name and write formulas for common acids.

Molecular compounds made of just nonmetals smallest piece is a molecule can’t be held together because of opposite charges. can’t use charges to figure out how many of each atom

Molecular are easier! Ionic compounds use charges to determine how many of each. Have to figure out charges. Have to figure out numbers. Molecular compounds name tells you the number of atoms. Uses prefixes to tell you the number

Prefixes (Table 6.5, p.159) 1 = mono- 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa-

Prefixes 9 = nona- 10 = deca- To write the name, write two words:

Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca- To write the name, write two words: Prefix name Prefix name -ide

Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca- To write the name, write two words: One exception is we don’t write mono- if there is only one of the first element. Prefix name Prefix name -ide

Prefixes Prefix name Prefix name -ide 9 = nona- 10 = deca- To write the name, write two words: One exception is we don’t write mono- if there is only one of the first element. No double vowels when writing names (oa oo) Prefix name Prefix name -ide

Name These N2O NO2 Cl2O7 CBr4 CO2 BaCl2

Write formulas for these diphosphorus pentoxide tetraiodine nonoxide sulfur hexafluoride nitrogen trioxide carbon tetrahydride phosphorus trifluoride aluminum chloride

Writing names and Formulas Acids Writing names and Formulas

Acids Compounds that give off hydrogen ions when dissolved in water. Must have H in them. will always be some H next to an anion. The anion determines the name.

Naming acids If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid HCl - hydrogen ion and chloride ion hydrochloric acid H2S hydrogen ion and sulfide ion hydrosulfuric acid

Naming Acids If the anion has oxygen in it, then it ends in -ate of -ite change the suffix -ate to -ic acid (use no prefix) HNO3 Hydrogen and nitrate ions Nitric acid change the suffix -ite to -ous acid HNO2 Hydrogen and nitrite ions Nitrous acid

Name these HF H3P H2SO4 H2SO3 HCN H2CrO4

Writing Acid Formulas Hydrogen will always be first name will tell you the anion make the charges cancel out. Starts with hydro?- no oxygen, -ide no hydro?, -ate comes from -ic, -ite comes from -ous

Write formulas for these hydroiodic acid acetic acid carbonic acid phosphorous acid hydrobromic acid

Section 6.6 Summary of Naming and Formula Writing OBJECTIVES: Use the flowchart in Figure 6.21 to write the name of a compound when given its chemical formula.

Section 6.6 Summary of Naming and Formula Writing OBJECTIVES: Use the flowchart in Figure 6.23 to write a chemical formula when given the name of a compound.

Helpful to remember... 1. In an ionic compound, the net ionic charge is zero (criss-cross method) 2. An -ide ending generally indicates a binary compound 3. An -ite or -ate ending means there is a polyatomic ion that has oxygen 4. Prefixes generally mean molecular; they show the number of each atom

Helpful to remember... 5. A Roman numeral after the name of a cation shows the ionic charge of the cation Use the handout sheets provided by your teacher!

Summary of Naming and Formula Writing For naming, follow the flowchart- Fig. 6.21, page 161 For writing formulas, follow the flowchart from Fig. 6.23, p. 162