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Chemical Formulas and Naming. Unit 4. Ions. Atoms that have a positive or negative charge To become an ion, an atom gains or loses electrons Cation = positively charged ion; Lose electron (s) Metals form positive ions Anion = negatively charged ion; Gain electron (s). Oxidation Numbers.

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slide2
Ions
  • Atoms that have a positive or negative charge
  • To become an ion, an atom gains or loses electrons
  • Cation = positively charged ion;
    • Lose electron (s)
    • Metals form positive ions
  • Anion = negatively charged ion;
    • Gain electron (s)
oxidation numbers
Oxidation Numbers
  • Indicate the charge on the ion
  • Found on the periodic table
  • Common oxidation numbers are given in additional table
  • Note:
    • Group 8 elements do not form ions; No ox #
    • Transition metals have multiple ox #’s
polyatomic ions
Polyatomic Ions
  • Def: tightly bound groups of atoms that behave as a unit and carry a charge
  • Ion composed of more than one atom
  • List of common polyatomic ions
polyatomic ions5
Polyatomic Ions

+1

  • NH4+ Ammonium

-1

  • NO3- Nitrate
  • NO2- Nitrite
  • CN- Cyanide
  • OH- Hydroxide
  • CH3COO- or C2H3O2- Acetate
  • MnO4- Permanganate
  • ClO3-Chlorate

-2

  • CO3-2 Carbonate
  • SO4-2 Sulfate
  • C2O4-2 Oxalate
  • CrO4-2 Chromate
  • Cr2O7–2 Dichromate

-3

  • PO4-3 Phosphate
compounds

Subscript “2”

Indicates how many atoms of the preceding element

are present.

The coefficient of “3” indicates the number of molecules

Compounds
  • What is a compound?
    • Compounds are composed of elements.
  • They are written by using chemical symbols and subscripts.
  • Chemical symbols are a capital letter or a capital letter and a lower case letter, that stands for an element.

3CO2

  • Chemical Symbols “C” and “O”
compounds7
Compounds
  • How many atoms are present in the following examples?

CH4

One carbon and four hydrogen = 5 atoms

C6H12O6

Six carbon, twelve hydrogen and six oxygen = 24 atoms total

NaOH

One sodium, one oxygen and one hydrogen = 3 atoms total

chemical formulas
Chemical Formulas
  • The elements are listed from most metallic on the left, to least metallic on the right.
  • Example;

For a compound made from sodium and oxygen.

Sodium is listed first and oxygen second.

Na2O

For a compound made from nitrogen and calcium.

Calcium is listed first and nitrogen second.

Ca3N2

writing formulas
Writing Formulas
  • Compounds are electrically neutral
  • Positive ion charge must balance the negative ion charge
  • Ex: Write the formula for a compound made from:
    • potassium and chlorine
    • calcium and bromine
criss cross method
Criss Cross Method
  • Ion charge crosses over to use as the subscript on the opposite atom
  • Useful when charges don’t balance out easily
  • Ex: aluminum and oxygen
    • Al2O3
chemical formula problems
Chemical Formula Problems
  • What are the formulas for compounds made from the following elements?

K3N

Potassium and nitrogen

Na2O

Sodium and oxygen

Rb3P

Phosphorus and rubidium

Al2S3

Aluminum and sulfur

molecular and ionic compounds
Molecular and Ionic Compounds
  • Ionic compounds are made from metal (cation)/ non-metal (anion) combinations.
  • Molecular compounds (Covalent compounds) are made from non-metal/ non-metal combinations.
naming compounds iupac nomenclature
Naming Compounds: IUPAC Nomenclature
  • International Union of Pure and Applied Chemistry
  • Systematic approach to naming compounds
  • Same names everywhere
  • Common names don’t tell us about their chemical composition
  • Ex: baking soda, quicksilver, lye, laughing gas
naming compounds binary ionic
Naming Compounds: Binary Ionic
  • Compound with only 2 different ions
    • 1 metal and 1 nonmetal
    • 1 positive ion and 1 negative ion
  • Name the cation and anion separately
  • Change the ending of the non-metal to “ide”
  • Example;
    • A compound made from chlorine and lithium becomes

Lithium chloride

name the following compounds
Name the Following Compounds.

K3N

Potassium nitride

Na2O

Sodium oxide

Rb3P

Rubidium phosphide

Al2S3

Aluminum sulfide

naming with transition metals binary ionic
Naming with Transition Metals (Binary Ionic)
  • Most metallic element is listed first.
  • If cation has more than one oxidation #, use Roman Numerals to indicate the charge
  • Ex: Fe = iron, Fe+2 = iron (II), Fe+3 = iron (III)
  • Anion = name of the element ending in

“-ide”

    • Ex: O = oxygen; O-2 = oxide
    • Ex: F = fluorine; F-1 = fluoride
examples with transition metals
Examples with Transition Metals

FeCl2

Iron (II) chloride

Cobalt (ll) carbonate

CoCO3

Manganese(Vl) oxide

Mn2O6

Strontium chloride

SrCl2

naming compounds tertiary ionic
Naming Compounds: Tertiary Ionic
  • Compounds with polyatomic ions
  • Separate cation from anion and name individually
  • Most metallic element is listed first.
  • The ending of the polyatomic remains the same.
  • Name of cation = name of element
  • Name of anion = name of polyatomic ion
    • Ex: CaCO3

Mg(NO3)2

Na2SO3

naming tertiary compounds
Naming Tertiary Compounds
  • Examples

Potassium nitrate

KNO3

Sodium oxalate

Na2C2O4

Rubidium phosphate

Rb3PO4

Ammonium sulfate

(NH4)2SO4

naming compounds binary molecular
Naming Compounds: Binary Molecular
  • Compound with only 2 different atoms
    • 2 nonmetals
  • Can combine in more than one way with the same elements
    • Ex: CO and CO2
  • Name the same way as ionic compounds (Most metallic element is listed first)
  • Need to include Greek prefixes to designate how many atoms of each element are present
greek prefixes for binary molecular compounds
Greek Prefixes for Binary Molecular Compounds

Mono = 1

Di = 2

Tri = 3

Tetra =4

Penta = 5

Hexa = 6

Hepta= 7

Octa = 8

Nona=9

Deca = 10

examples of molecular compounds
Examples of Molecular Compounds

P2O5

diphosphorus pentoxide

N2O

dinitrogen monoxide

monocarbon dioxide

or

carbon dioxide

CO2

CO

carbon monoxide

summary of naming and formula writing
Summary of Naming And Formula Writing
  • In an ionic compound, the ionic charges add to zero.
  • An “-ide” ending indicates a binary compound.
  • An “-ite” or “-ate” ending indicates a polyatomic anion is in the formula.
  • Roman numerals are used to indicate the charges on transition metals.
  • Greek prefixes are used to indicate the number of atoms present in a molecular compound.
balancing equations why
Balancing Equations: WHY?
  • Law of Conservation of Matter – matter can neither be created nor destroyed 
  • Anything on the left hand side must be found on the right hand side – cannot magically lose or gain atoms
balancing equations coefficients
Balancing Equations: Coefficients
  • What is a coefficient?
    • Number found in front of a compound’s formula
    • Indicates how many molecules are involved in the reaction
  • Add coefficients to balance the equation
  • Versus subscripts:
    • subscripts indicate how many atoms in a molecule

(ex: CaBr2 – 2 Br atoms)

    • coefficients indicate how many molecules in a reaction (ex: 2CaBr2 – 2 CaBr2 molecules; 4 Br atoms)
symbols used in equations
Symbols Used in Equations

+

- separates 2 reactants or 2 products

- separates reactants from products; “yields”

(s)

- solid state

(l)

- liquid state

symbols used in equations cont
Symbols Used in Equations cont.

(aq)

- aqueous solution

(g)

- gaseous state

- heat

Formula written above or below yield sign

- catalyst

balancing equations
Balancing Equations
  • Example

HgO (s) Hg (l) + O2 (g)

balancing equation examples
Balancing Equation Examples
  • __C4H10 + __O2 __CO2 + __H2O
  • For these equations balance H then C then O (known as combustion equations)

__CaCO3 + __HCl __ CO2 + __CaCl2 + __H2O

types of reactions
Types of Reactions
  • There are millions of different chemical reactions
  • We need to learn how to recognize patterns of chemical behavior to predict products in many reactions
  • Most reactions can be divided into five main types:

1- Synthesis (or Combination)

2- Decomposition

3- Single displacement reactions

4- Double displacement reaction

5- Combustion

synthesis combination reactions
Synthesis (Combination) Reactions
  • In a synthesis reaction, two or more substances combine to form another substances

(reactant + reactant  1 product)

  • General Formula: A + B AB
  • Example: 2H2 (g) + O2 (g) 2H2O
synthesis combination exceptions
Synthesis (Combination) Exceptions
  • Reaction of metal oxide and water yields a metal hydroxide (OH-1)
  • Examples

MgO + H2O Mg(OH)2

CaO + H2O Ca(OH)2

LiO + H2O Li(OH)

decomposition reactions
Decomposition Reactions
  • Occurs when one substance breaks down or decomposes into two or more substance

(1 Reactant  Product + Product)

  • General Formula: AB A + B
  • Example: 2 H2O (l) 2H2 (g) + O2 (g)
decomposition exceptions
Decomposition Exceptions

Carbonates, chlorates, and hydroxides are special case decomposition reactions that do not go to the elements.

  • Carbonates (CO32-) decompose to carbon dioxide and a metal oxide
    • Example: CaCO3  CO2 + CaO
  • Chlorates (ClO3-) decompose to oxygen gas and a metal chloride
    • Example: 2 Al(ClO3)3  2 AlCl3 + 9 O2
  • Hydroxides (OH-1) decompose to metal oxide and water
    • Example: Ca(OH)2 CaO + H2O
single replacement reactions
Single Replacement Reactions
  • A single displacement reaction occurs when one element replaces another element in a compound.
  • General Formulas
    • 1st case: A + BC AC + B (A is a metal)
    • 2nd case: A + BC BA + C (A is a nonmetal)
  • Example: Cu(s) + 2AgNO3(aq) Cu(NO3)2 (aq) + 2Ag(s)
single replacement exceptions
Single Replacement Exceptions
  • Reaction of a metal and an acid produces an ionic compound and hydrogen gas (H2)
    • Example

Mg + HCl  MgCl2 + H2

  • Reaction of a metal with water produces a metal hydroxide (OH-1) and hydrogen gas (H2)
    • Example

Ca + H2O  Ca(OH)2 + H2

double replacement reactions
Double Replacement Reactions
  • A double displacement reaction takes place when two ionic compounds in solution combine
  • In this type of reaction a precipitate forms
    • This type of reaction yields a solid (an insoluble compound that doesn’t dissolve) and a new solution (soluble-dissolves in water)
  • How do we determine if something is soluble or insoluble? USE YOUR SOLUBILITY RULES (TABLE)
    • More about this later….
  • The positive ion of one compound replaces the positive ion of the other to form two new compounds.
  • Compound + compound  compound+ compound
  • General Formula: AB + CD  AD + CB
double replacement reactions38
Double Replacement Reactions
  • Think about it like “foil”ing in algebra, first and last ions go together + inside ions go together
  • Example:

AgNO3(aq) + NaCl(s)  AgCl(s) + NaNO3(aq)

  • Another example:

K2SO4(aq) + Ba(NO3)2(aq)  KNO3(aq) + BaSO4(s)

2

combustion reactions
Combustion Reactions
  • Combustion reactions occur when a hydrocarbon (an organic compound) reacts with oxygen gas to produce carbon dioxide gas (CO2) and water (H2O)
  • Used to heat homes and run automobiles (octane, as in gasoline, is C8H18)
  • General Formula:

hydrocarbon + oxygen ----> carbon dioxide and water

CxHy + O2  CO2 + H2O

  • Example (Start balancing with hydrogen, then carbons, and finally oxygen)

CH4(g) + 2O2(g) ----> 2H2O(g) + CO2(g)

2C2H6(g) + 7O2(g) ----> 6H20(g) + 4CO2(g)

acid nomenclature
Acid Nomenclature

Binary 

Ternary

An easy way to remember which goes with which…

“In the cafeteria, youATEsomethingICky”

naming acid examples
Naming Acid Examples

hydrobromic acid

  • HBr (aq)
  • H2CO3
  • H2SO3

 carbonic acid

 sulfurous acid

organic compounds hydrocarbons
Organic Compounds (Hydrocarbons)
  • Contain carbon surrounded by hydrogen's
  • Have covalent bonds
  • Have low melting points
  • Have low boiling points
  • Burn in air (oxygen)
  • Are soluble in nonpolar solvents
  • Form large molecules
organic compounds hydrocarbons44
Organic Compounds (Hydrocarbons)
  • Contain C and H only
  • Contain single bonds C-C
  • Have 4 bonds to every carbon (C) atom
  • Are nonpolar
complete structural formulas
Complete Structural Formulas

Show the bonds between each of the atoms

H H

 

H  C  H H C H

 

H H

CH4 , methane

iupac names
IUPAC Names

Name # carbons Structural Formula

Methane 1 CH4

Ethane 2 CH3CH3

Propane 3 CH3CH2CH3

Butane 4 CH3CH2CH2CH3

Pentane 5 CH3CH2CH2CH2CH3

iupac names47
IUPAC NAMES

Name # carbons Structural Formula

Hexane 6 CH3CH2CH2CH2CH2CH3

Heptane 7 CH3CH2CH2CH2CH2CH2CH3

Octane 8 CH3CH2CH2CH2CH2CH2CH2CH3

Nonane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3

Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

iupac names48
IUPAC NAMES
  • Sometimes there’s a branch off of a main chain
  • To name a branch use the same prefixes on the previous 2 slides, but the suffix becomes –yl
  • For example:
    • 1 carbon branch would be methyl
    • 2 carbon branch would be ethyl
mnemonic for first four prefixes
Mnemonic for First Four Prefixes

First four prefixes

Meth-

Eth-

Prop-

But-

  • Monkeys
  • Eat
  • Peeled
  • Bananas
general formulas
General Formulas
  • Alkanes = CnH2n+2(formula for hydrocarbons)
  • Alkenes = CnH2n
  • Alkynes = CnH2n-2
rules for naming hydrocarbons
Rules for Naming Hydrocarbons

1. Naming the longest chain (root)

(a) Find the longest continuous chain of carbon atoms.

(b) Select the root that corresponds to the number of carbon atoms in this chain. Add the suffix –ane to the chain root

(c ) If the chain forms a ring, the name is preceded by cyclo-

2. Locate the branches (prefix) and assign them the lowest set of numbers

(a) To specify where the branch occurs along the chain, number the main- chain C atoms consecutively, starting at the end closer to a branch, to achieve the lowest numbers for the branches. Precede each branch

name with the number of the chain C atom to which that branch is

attached.

(b) Each branch name consists of a subroot (number of C atoms) and the ending -ylto signify that it is not part of the main chain. Branch names precede the chain name with the number in front. When two or more branches are present, name them in alphabetical order.

(c) If the compound has no branches, the name consists of the root

and suffix.

rules for naming hydrocarbons52
Rules for Naming Hydrocarbons

3. Use di-, tri-, tetra-, etc. to combine similarly named branches

4. Separate numbers with commas and numbers and letters with dashes

examples55
Examples
  • Draw the following molecules
    • 2, 2, 4-trimethyl pentane
    • 3, 4-diethyl 2,2-dimethyl 3-propyl decane
    • 2, 3-diethyl 4-propyl octane