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Naming Ionic Compounds

• NaF -

• LiCl -

• MgO -

Naming Ionic Compounds

• NaF- Sodium Ion and Fluoride ion

• LiCl- Lithium Ion and Chloride Ion

• MgO- Magnesium Ion and Oxide Ion

Naming Ionic Compounds

• NaF - Sodium Fluoride

• LiCl - Lithium Chloride

• MgO - Magnesium Oxide

More PracticeCd(OH)2

Cadmium

Hydroxide

Ca(ClO)2

Calcium

Hypochlorite

AgCN

Silver Cyanide

Na2SO4

Sodium Sulfate

Na2SO3

Sodium Sulfite

KClO4

Potassium

Perchlorate

Ions You Should Know

http://sest.vsu.edu/~vvilchiz/ionsacids.htm

Properties of Molecular & Ionic Compounds

Chemical compounds are classified as organic or inorganic.

Organic compounds are compounds that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen; they do not contain metals.

Inorganic compounds are compounds composed of elements other than carbon and usually contain at least one metal atom.

Chemical Substances; Formulas and Names

• Naming simple compounds

An important class of molecular substances that contain carbon is the organic compounds.

Organic compounds make up the majority of all known compounds.

The simplest organic compounds are hydrocarbons, or compounds containing only hydrogen and carbon.

Common examples include methane, CH4, ethane, C2H6, and propane, C3H8.

Chemical Formulas; Molecular Substances

• Organic compounds

A covalent compound as we said before is formed by sharing electrons between 2 nonmetals or metalloids.

These compounds are usually molecular and are named using a prefix system.

When naming these compounds name the element further to the left (in the periodic table) first, then the one on the right.

Naming Covalent Compounds

You name the first element using the exact element name.

Name the second element by writing the root of the element’s name and add the suffix “–ide.”

If there is more than one atom of any given element, you add the Greek prefix denoting how many atoms of that element are present. Table lists the Greek prefixes used.

If only one atom of the second element is present it gets the prefix “mono”

Naming Covalent Compounds

Here are some examples of prefix names for binary molecular compounds.

PF5 phosphorus pentafluoride

SO2 sulfur dioxide

SF6 sulfur hexafluoride

N2O4 dinitrogen tetroxide

CO carbon monoxide

Naming Covalent Compounds

Acids are traditionally defined as compounds that could donate an H+; however, they are acids only in the presence of water. In other words before they enter the liquid they are covalent compounds and they are NOT acids.

There are two main types of acids:Binary acids consist of a hydrogen ion and any single anion. For example, HCl is hydrochloric acid.

An oxoacid is an acid containing hydrogen, oxygen, and another element. An example is a HNO3, nitric acid. (see Figure 2.23)

Naming Acids

Naming Acids

• Binary Acids– Start with the prefix “Hydro” which represents the

Hydrogen, followed it with the root of the name of the second element and append the ending –oic acid.

• Oxoacids– Use the root of the “E” element if the ion taking part in

the acid had an ending in –ate to the root append the ending –ic acid, if it ends on –ite then append the ending –ous acid. If the ion had a prefix use the same prefix.

Naming Acids

• Examples:– HCl(g) Hydrogen Chloride– HCl(aq) HydroChloric Acid– H2S(g) Dihydrogen Sulfide– H2S(aq) HydroSulfic Acid– H3PO4(aq) Phosphoric Acid– HClO4(aq) Perchloric Acid– HClO(aq) Hypochlorous Acid

Ionic Compounds Formulas

• How do we know how many atoms of each ion we need?– A simple crossing of the charges can answer that question about

90% of the time.• Example: Mg2+ and PO4

3-

Mg3(PO4)2

Check the charges… 3 x (+2) = +6 2 x (-3) = -6

– When they combined they cancel to yield a neutral compound.

Ionic Compounds Formulas

• The crossing technique does not work if the magnitude of the charges is the same

• Example: Mg2+ and CO32-

Mg2(CO3)2

This is incorrect since we want the lowest ratio possible which is 1:1 to yield MgCO3

Ionic Compounds Properties

• Ionic compounds have properties completely different from their component elements.– Example: Table Salt (NaCl)

• Sodium (Na) in the presence of water reacts violently heating up the water and producing hydrogen if the temperature of the water is high enough the hydrogen can ignite explosively.

• Chloride (Cl) Green poisonous and corrosive gas. If inhaled will destroy the nasal passages then dissolve in the stomach producing high concentration of hydrochloric acid which will destroy the stomach lining producing ulcers.

• Salt (NaCl) posses none of the properties mentioned above.

Ionic Structure

•Ions form a 3-D lattice.

•The coulombic (electrostatic) attraction is so high that in order to separate one ion from the lattice requires a lot of energy (Hlatt).

•The lattice energy depends on charge and size of the ions.

Lattice Energy

• Since the lattice energy is an electrostatic interaction the more separated the charges are the weaker the interaction is.– Bigger ions have lower lattice energies

• The higher the charge of the ions the stronger they will attract ions of the opposite charge.

• When size and charge point to opposite trends the charge will outweigh the size.– From smallest atom to biggest atom there is only 1.7x factor. From

a +1 to +2 that is already a 2x factor.

12

21

r

qqH latt

Properties of Ionic Substances

• Dues to the charged interaction a blow to a crystal leads to the possibility of splitting the crystal since we will force like charged particles to interact.

• Ionic compounds have high melting/boiling points since in order to move the ions from their respective spots it will require breaking the lattice.

Ionic Solutions

• However, if we do melt an ionic compound it will be able to conduct current.

• When ionic compounds are placed in a solvent the produced solution conducts electricity. The higher the number of ions the higher the conductivity.

• More when we cover chapter 4.

A hydrate is a compound that contains water molecules weakly bound in its crystals.

Hydrates are named from the anhydrous (dry) compound, followed by the word “hydrate” with a Greek prefix to indicate the number of water molecules per formula unit of the compound.

For example, CuSO4. 5H2O is known as

copper(II)sulfate pentahydrate. (see Figure 2.24)

Naming Hydrates

Determining Chemical Formulas

• Determining both empirical and molecular formulas of a compound from the percent composition.

The percent composition of a compound leads directly to its empirical formula.

An empirical formula (or simplest formula) for a compound is the formula of the substance written with the smallest integer (whole number) subscripts.

Determining Chemical Formulas

• The percent composition of a compound is the mass percentage of each element in the compound.

We define the mass percentage of “A” as the parts of “A” per hundred parts of the total, by mass. That is,

%100whole the of mass

whole in A"" of mass A"" % mass

Mass Percentages from Formulas

• Let’s calculate the percent composition of butane, C4H10.

First, we need the molecular mass of C4H10.amu 48.0 amu/atom 12.0 @ carbons 4 amu 10.0 amu/atom 1.00 @ hydrogens 10

amu 58.0 HC of molecule 1 104

Now, we can calculate the percents.C%8.82%100 C % total amu 0.58

C amu 48.0

H%2.17%100 H % total amu 0.58H amu 10.0

Determining Chemical Formulas

• Determining the empirical formula from the percent composition.

Benzoic acid is a white, crystalline powder used as a food preservative. The compound contains 68.8% C, 5.0% H, and 26.2% O by mass. What is its empirical formula?

In other words, give the smallest whole-number ratio of the subscripts in the formula

Cx HyOz

Determining Chemical Formulas

• Determining the empirical formula from the percent composition.

For the purposes of this calculation and making calculations simpler, we will assume we have 100.0 grams of sample benzoic acid.

Then the percentage of each element equals the mass of each element in the sample.

Since x, y, and z in our formula represent mole-mole ratios, we must first convert these masses to moles.

Determining Chemical Formulas

C mol )3(73.5g 12.0C mol 1

C g 8.68

H mol 0.5g 1.0H mol 1

C g 0.5

O mol)7(63.1g 16.0O mol 1

O g 2.26

This isn’t quite a whole number ratio, but if we divide each number by the smallest of the three, a better ratio might emerge.

Determining the empirical formula from the percent composition.

Our 100.0 grams of benzoic acid would contain:

Determining Chemical Formulas

Determining the empirical formula from the percent composition.

Our 100.0 grams of benzoic acid would contain:

3.501.63(7)C mol 73.5

3.01.63(7)H mol 0.5

1.001.63(7)O mol )7(63.1

now it’s not too difficult to see that the smallest whole number ratio is 7:6:2. The empirical formula is C7H6O2 .

Determining Chemical Formulas

• Determining the “true” molecular formula from the empirical formula.

An empirical formula gives only the smallest whole-number ratio of atoms in a formula.

The “true” molecular formula could be a multiple of the empirical formula (since both would have the same percent composition).

To determine the “true” molecular formula, we must know the “true” molecular weight of the compound.

Determining Chemical Formulas

• Determining the “true” molecular formula from the empirical formula.

For example, suppose the empirical formula of a compound is CH2O and its “true” molecular weight is 60.0 g/mol.The molar weight of the empirical formula (the “empirical weight”) is only 30.0 g/mol.This would imply that the “true” molecular formula is actually the empirical formula doubled 2(CH2O) or

C2H4O2

Molecular and structural formulasand molecular models.

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A model of a portion of a Sodium Chloride crystal.

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Common Ions of the transition metals

List of Polyatomic Ions

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Greek Prefixes for Covalent Compounds Nomenclature

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Making and Acid

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Molecular model of nitric acid.

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Figure 2.24: Copper (II) sulfate. Photo courtesy of James Scherer.

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Naming Flow Chart

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Naming Flow Chart II

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Naming Acids Flow Chart

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