Unit 5 “Chemical Names and Formulas” H2O Unit 5 “Chemical Names and Formulas” Chemistry Troy High School Mr. Blake

Section 9.1 Naming Ions

Atoms and Ions are electrically neutral. Same number of p+ and e- - atoms with a charge (+ or -) Made by gaining or losing . Only electrons can move

F1- O2- An Anion is… A negative ion = electrons. Nonmetals gain electrons. Charge is written as a superscript on the right. F1- Has gained electron (-ide is new ending = ) O2- Gained electrons ( )

K1+ Ca2+ A Cation is… A positive ion = electrons. lose electrons Has lost electron (no name change for positive ions) More protons than electrons Ca2+ Has lost electrons

Predicting Ionic Charges Group 1A: Lose electron to form ions H1+ Li1+ Na1+ K1+ Rb1+

Predicting Ionic Charges Group 2A: Loses electrons to form ions Be2+ Mg2+ Ca2+ Sr2+ Ba2+

Predicting Ionic Charges Loses electrons to form ions Group 3A: B3+ Al3+ Ga3+

Predicting Ionic Charges ! Group 4A elements rarely form ions (they tend to share) Group 4A: Do they lose 4 electrons or gain 4 electrons?

Predicting Ionic Charges Nitride Gains _ electrons to form ions Group 5A: P3- Phosphide As3- Arsenide

Predicting Ionic Charges Oxide Gains electrons to form ions Group 6A: S2- Sulfide Se2- Selenide

Predicting Ionic Charges Gains _ electron to form ions Group 7A: F1- Fluoride Br1- Bromide Cl1- Chloride I1- Iodide

Predicting Ionic Charges Group 8A: Stable noble gases form ions!

Predicting Ionic Charges Group B elements: Many transition elements have possible charge. Use of Roman numerals to show charges Iron (II) = Iron (III) = Show roman numerals up to 5.

Naming Cations system – use roman numerals in parenthesis to indicate the charge value 2. Classical method – uses root word with suffixes (-ous, -ic) Does not give true value

Naming cations If the charge is always the (like in the Group A metals) just write the of the metal. Calcium = 𝐶𝑎 +2 metals can have more than one type of charge. Indicate charge as roman numeral in after the name of the metal (Table 9.2, p.255) Iron (IV) =

Predicting Ionic Charges Some elements also have more than one possible charge. Tin (II) = Lead ( ) = Pb2+ Tin (IV) = Lead ( ) = Pb 4+

Predicting Ionic Charges Group elements: Some transition elements have only one possible oxidation state, such as these three: **Do not use roman numerals for these Silver = Zinc = Cadmium =

Practice by naming these: Ca2+ Al3+ Fe3+ Fe2+ Pb2+ Li+

Write symbols for these: Potassium ion Magnesium ion Copper (II) ion Chromium (IV) ion Barium ion Mercury (II) ion

Anions are the same charge Change the ending to _ Naming Anions Anions are the same charge Change the ending to _ F1- a Fluorine atom will become a ion.

Practice by naming these: Cl- N3- Br- O2- Ga3+

Write symbols for these: Sulfide ion Iodide ion Phosphide ion Strontium ion

Polyatomic ions are… Groups of atoms that together, have an charge, and one name. Usually end in – or - _ Acetate: C2H3O2- Nitr : NO3- Nitr : NO2- Permanganate: MnO4- Hydroxide: OH- and Cyanide: CN-?

Know Table 9.3 on page 257 Sulf : SO42- Phosph : PO43- Sulf : SO32- Carbonate: CO32- Chromate: CrO42- Dichromate: Cr2O72- Phosph : PO43- Phosph : PO33- Ammonium: NH41+ (One of the few positive polyatomic ions)

H + Polyatomic ion =…. If the polyatomic ion begins with H, then put “hydrogen” in front of the polyatomic ion: H1+ + CO32- → HCO31- hydrogen + carbonate → hydrogen carbonate ion HSO3 HPO4 HCO3

Helpful Hints on Oxy-Anions 1. _________: smaller # of oxygen 2. _________: larger # of oxygen Ex. NO3- ____________________________ NO2- ____________________________ SO42- ____________________________ SO32- ____________________________

A Guide to Determine Whether the –ate Formula is –XO3 or –XO4: 1 2 3 4 5 6 13 14 15 16 17 18 Transition Metals B C N Si P S Cl As Se Br I

Section 9.2 Naming and Writing Formulas for Ionic Compounds

Writing Ionic Compound Formulas Example: Iron (III) chloride 1. Write the cation and anion with CHARGES! 2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.

Writing Ionic Compound Formulas Example: Aluminum sulfide 1. Write the cation and anion with CHARGES! 2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.

Writing Ionic Compound Formulas Example: Zinc hydroxide 1. Write the cation and anion with CHARGES! 2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.

Writing Ionic Compound Formulas Example: Magnesium carbonate (note the 2 word name) 1. Write the formulas for the cation and anion, including CHARGES! Mg2+ CO32- 2. Check to see if charges are balanced. They are balanced!

Writing Ionic Compound Formulas Example: Barium nitrate (note the 2 word name) 1. Write the cation and anion with CHARGES! 2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.

Writing Ionic Compound Formulas Example: Ammonium sulfate 1. Write the cation and anion with CHARGES! 2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.

Writing Ionic Compound Formulas Example: Aluminum phosphate 1. Write the formulas for the cation and anion, including CHARGES! Al3+ PO43- They ARE balanced! 2. Check to see if charges are balanced.

Naming Ionic Compounds 1. Cation , then anion 2. Monatomic cation = name of the element Ca2+ = ion 3. Monatomic anion = root + -ide Cl- = CaCl2 =

Naming Ionic Compounds (Metals with multiple oxidation states) If the metal can have more than one charge ( ), use a Roman numeral in their name: PbCl2  use the to find the charge on the cation (chloride is always 1-) is the lead ( ) cation PbCl2 = lead ( ) chloride

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

Practice by writing the formula or name as required… Iron (II) Phosphate Stannous Fluoride Potassium Sulfide Ammonium Chromate MgSO4 FeCl3

Section 9.3 Naming and Writing Formulas for Molecular Compounds

Molecular compounds are… Made of only Smallest part is a Can’t use charges to figure out how many of each atom (there are no charges present / they share electrons)

Molecular compounds are easier! compounds use to determine how many of each. Figure out charges and criss-cross numbers. Molecular compounds: the name tells you the number of atoms. Uses to tell you the exact number of each element present!

Prefixes (Table 9.4, p.269) 9 = nona- 10 = 1 = mono- 2 = di- 3 = 4 = tetra- 5 = 6 = hexa- 7 = hepta- 8 = octa-

Prefixes Prefix + name -ide To write the name, include: One exception is we don’t write if there is only of the element. Normally, we do not have double vowels when writing names (oa oo) Prefix + name -ide

Practice by naming 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 (Ionic compound)

Section 9.4 Naming and Writing Formulas for Acids and Bases

Acids are… Compounds that give off ions (H+) when dissolved in water (the Arrhenius definition) Formula starts with . Always be some Hydrogen next to an . determines the name.

Rules for Naming acids: Name it as a normal compound first If the anion attached to hydrogen ends in -ide, put the prefix and change -ide to - acid In other words, if it’s just Hydrogen and one other nonmetal HCl = H2S = acid acid

Naming Acids If the anion has oxygen in it, then it ends in -ate or -ite Change -ate to -ic acid (use no prefix) Example: HNO3 Hydrogen + nitrate = Change -ite to -ous acid (use no prefix) Example: HNO2 Hydrogen + nitrite =

Naming Acids ____-ide ____-ate ____-ite hydro-___-ic acid Normal ending ____-ide ____-ate ____-ite Acid name is… hydro-___-ic acid _____-ic acid _____-ous acid

Practice by naming these: HF H3P H2SO4 H2SO3 HCN H3PO4

Writing Acid Formulas – in reverse! Hydrogen will be listed first The name will tell you the Be sure the charges cancel out. Starts with hydro? No hydro? Anion is , ends in –ide -ate anion comes from – ending -ite anion comes from – ending

Write formulas for these: hydroiodic acid chloric acid carbonic acid phosphorous acid hydrobromic acid

Names and Formulas for Bases Base - an ionic compound that produces ions ( ) when dissolved in water (the Arrhenius definition) Named the same way as other ionic compounds: Name of cation ( ) followed by name of anion (which will be ).

Names and Formulas for Bases NaOH = Ca(OH)2 = To write the formula: Write symbol for metal cation Followed by hydroxide ion (OH1-) Use criss-cross method to balance the charges.

Practice by writing the formula for the following: Magnesium hydroxide Iron (III) hydroxide Zinc hydroxide

Section 9.5 The Laws Governing Formulas and Names

Some Laws: Law of Proportions- in a sample of a chemical compound, the of the are always in the proportions. In every molecule of H2O (water), the mass ratio of H:O is 1:8

Some Laws: Law of Proportions- Whenever two elements form than one compound, the masses of one element that combine with the mass of the other element are in the ratio of small . H2O (water) and H2O2 (hydrogen peroxide) 2:1 2:2 2g:16g 2g:32g

https://www.youtube.com/watch?v=0OOcpiTiXzM Law of Definite Proportions - Law of Multiple Proportions by Brightstorm

Summary of Naming and Formula Writing For naming, follow the flowchart- Figure 9.20, page 277 For writing formulas, follow the flowchart from Figure 9.22, page 278

Helpful to remember... 1. In ionic compounds, the net charge is _ (criss-cross method) 2. Put -ide at the end of monatomic 3. An -ite or -ate ending means there is a ion that has 4. Prefixes generally mean ; they show the number of each atom

Helpful to remember... 5. A Roman numeral after the name of a cation is the of the cation