Naming Compounds and Writing Formulas GPS 9

Chemical Properties of Groups Oxidation Numbers

Naming Ions Recall: oxidation numbers tell us which ion is formed during chemical reactions Naming ions – (name of metal) ion – (name of nonmetal) –ide ion Examples – Na 1+ sodium ion – O 2- oxide ion

Naming Ions Name the following ions: Mg 2+ F 1- Cl 1- magnesium ion fluoride ion chloride ion

Ionic Bonding – occurs between a metal ions and a nonmetal ions – involves a transfer of electrons – ions are separate, but are attracted to one another because of opposite charges – ions form a compound

Covalent Bonding Covalent bonding – occurs between two nonmetal atoms – involves a sharing of electrons – combine to form a molecule

Writing Chemical Formulas Use the criss-cross method: Example: sodium chlorine potassiumoxygen

Writing Chemical Formulas Write the chemical formula: magnesiumchlorine Mg 2+ Cl 1- MgCl 2

Writing Chemical Formulas Write the chemical formula: lithiumsulfur Li 1+ S 2- Li 2 S

Writing Chemical Formulas Make sure you simplify your formula so that it has the smallest subscripts possible. Example: Calcium reacts with Sulfur Ca 2+ S 2- Ca 2 S 2 Simplify to CaS

Writing Chemical Formulas Example: BoronNitrogen

Writing Chemical Formulas Transition metals, lead (Pb), and tin (Sn) – Many have several oxidation numbers Example: – Copper commonly forms ions with a +1 or +2 charge – Copper (I), Copper (II) distinguishes between oxidation numbers

Roman Numerals Roman NumeralOxidation number I+1 II+2 III+3 IV+4 V+5 VI+6 VII+7 VIII+8 IX+9 X+10

Writing Chemical Formulas Write the chemical formula: iron (III)oxygen Fe 3+ O 2- Fe 2 O 3

Writing Chemical Formulas Write the chemical formula: copper (II)chlorine Cu 2+ Cl 1- CuCl 2

Writing Chemical Formulas Some transition metals always have the same oxidation number, therefore no roman numeral is used when named Determine the formula for each of the following: – Silver chloride – Zinc chloride Transition metalOxidation numberIon symbol Silver1+1+ Ag + Zinc2+2+ Zn 2+ Cadmium2+2+ Cd 2+

Naming Compounds (Ionic Bonding Occurring) ** We use the IUPAC naming system** (International Union of Pure and Applied Chemistry) Steps 1. Write the name of the cation (positive ion) 2. If there is a transition metal, use a roman numeral to indicate the charge. 3. Write the name of the anion (negative ion), but change the ending to –ide Example NaClsodium chloride MgBr 2 magnesium bromide Fe 2 O 3 iron (III) oxide

Naming Compounds (Ionic Bonding Occurring) Name the following: MgCl 2 NiBr Li 2 O * What about molecules? (covalent bonding) CO 2

Naming Molecules (Covalent Bonding) Law of multiple proportions - the proportion in which elements combine can be expressed in small whole numbers - nonmetals can combine in different ratios, therefore we must use prefixes when naming covalent molecules

Prefixes used in Molecules (When covalent bonding occurs) mono-1 di-2 tri-3 tetra-4 penta-5 hexa-6 hepta-7 octa-8 nona-9 deca-10

Naming Molecules (Covalent bonding occurring) Same as naming ionic compounds, except we must use prefixes to indicate the number of atoms of each element. Note: metalloids behave as nonmetals when bonding. Example: N 2 O 5 N 3 O 7 PCl 5 NO BF 3 P 2 O trinitrogen heptoxide phosphorus pentachloride nitrogen monoxide boron trifluoride diphosphorus monoxide dinitrogen pentoxide

Common Substances to Recognize H 2 Owater CH 4 methane NH 3 ammonia

Summary: Ionic Bonding -Metal and nonmetal -Naming: the metal, then the nonmetal (ending changed to –ide) -Electrons transferred -Smallest unit: ions Covalent Bonding -Two nonmetals -Naming: the first nonmetal, then the second nonmetal (ending changed to – ide). Use prefixes. -Electrons shared -Smallest unit: molecule

Polyatomic Ions Polyatomic ions – many atoms bonded together with a single charge on the entire molecule When bonding with another ion, polyatomic ions form ionic bonds

Common Polyatomic Ions ammoniumNH 4 + hydroxideOH - acetateC 2 H 3 O 2 - nitrateNO 3 - chlorateClO 3 - carbonateCO 3 2- sulfateSO 4 2- phosphatePO 4 3-

Polyatomic Ions: Writing Formulas Before using the criss-cross method, place parentheses around the polyatomic ion – Example calcium and nitrate Ca 2+ NO 3 - Ca(NO 3 ) 2 calcium nitrate

Polyatomic Ions in Ionic Bonding Examples: berylliumhydroxide sodiumacetate magnesiumphosphate bariumsulfate ammoniumoxygen silver (II)nitrate

Naming Compounds with Polyatomic Ions Examples: Ca(OH) 2 (NH 4 ) 2 O Li 3 PO 4 calcium hydroxide ammonium oxide lithium phosphate

Naming Acids Hydrogen bonded with an element: hydro__________ic acid Examples HBr H 2 S hydrobromic acid hydrosulfuric acid

Naming Acids Hydrogen bonded with a polyatomic ion: ______________ic acid Examples HNO 3 H 2 SO 4 nitric acid sulfuric acid

Types of Formulas Molecular formula – shows the true number of atoms of each element in a compound Empirical formula – shows the lowest (smallest) ratio of atoms in a compound Structural formula – shows the physical arrangement of atoms within a compound

Types of Formulas Example:Benzene Molecular formula – C 6 H 6 Empirical formula – CH Structural Formula

Types of Formulas Example: What type of formula is this? Give the molecular formula and the empirical formula for this molecule.

Types of Formulas Note: If the molecular formula cannot be reduced, then the empirical formula is the same as the molecular formula. Example: If the molecular formula is C 3 H 7, what is the empirical formula?

Diatomic Molecules Naturally occurring diatomic molecules: Br 2, I 2, N 2, Cl 2, H 2, O 2, F 2 - these occur as gases at room temperature * except Br 2 (liquid at room temp) * except I 2 (solid at room temp) - naming: ex: O 2 oxygen gas N 2 nitrogen gas Br 2 liquid bromine I 2 solid iodine