2.4.2 Naming Chemical Compounds

Question 1

Naming Chemical Compounds

Answer 1

• Ionic compounds are named using rules for their cation and anion components.
• Binary molecualr compounds are named using a system of Greek Prefixes.
• Bases are named using the regular rules

Question 2

ions

Answer 2

• When positively charged ions(cations) have only one possible charge (oxidation state), they are identified by their elemental names, followed by the word “ion”.
• Polyatomic cations are identified by their group name, ending in “-ium”, followed by the word “ion”.

Question 3

transition metals

Answer 3

• When positively charged ions, particularly transition metal ions, have more than one possible charge, they are identified by their elemental names, followed by Roman numerals indicating their charge, and then the word “ion”.
• Under an older system still in use, when positively charged ions (cations) have more than one possible charge (oxidation state), the suffix “-ous” indicates the lower charge and the suffix “-ic” indicates the higher charge

Question 4

note

Answer 4

• Negatively charged ions are named using the suffix “-ide” attached to their unambiguous stem to indicate their anion status.
• The suffixes “-ate” and “-ite” identify negatively charged polyatomic ions containing oxygen, also called oxyanions. The suffix “-ate” refers to the most common oxyanion; “-ite” has the same charge but one fewer atom of oxygen.
• The prefix “per-“ indicates one oxygen more than an “-ate” suffix, while the prefix “hypo-“ indicates one less oxygen than an “-ite” suffix. The “per-“ prefix is added to “-ate” and “hypo-“ to “-ite” in these cases.
• The prefix “bi-” indicates an anion having hydrogen as part of its structure.
• The prefix “di-” indicates a polyatomic ion containing
  multiple metal atoms.

Question 5

example

Answer 5

• Example 1: Copper may have more than one oxidation state. Here it is Cu2+ so copper is expressed as copper(II). Sulfate is a negatively charged polyatomic ion. This compound is copper(II) sulfate. The alternative name is cupric sulfate, which indicates the higher charged version of copper is present in this compound.
• Example 2: Iron may have more than one oxidation state. Here it is Fe3+ so iron is expressed as iron(III). Carbonate is a negatively charged polyatomic ion. This compound is iron(III) carbonate. The alternative name is ferric carbonate, which indicates the presence of the higher charged version of iron in this compound.
• Note that the cationic charge balances with the anionic charge

Question 6

binary

Answer 6

• Most molecules are identified in two parts: If the first element does not have a subscript, only the name of the first element is used. When the first element in a molecule has a subscript, Greek prefixes are used to indicate how many atoms of the element are present.
• The second element is named using a Greek prefix followed by the unambiguous stem of the second element present, followed by the suffix “-ide”.
• Second elements in binary molecular compound names always have prefixes

Question 7

bases

Answer 7

• Bases are named as ionic compounds.
• Oxyacids are named from their component anion, so acids with “-ate” suffixes become “-ic acids”. A nitrate containing acid is thus nitric acid.
• Acids with “-ite” suffixes become “-ous acids”,so a nitrite ion containing acid is nitrous acid.
• A “per_ate” anion becomes a “per_ic acid”, so a perchlorate ion containing acid is perchloric acid.
• A “hypo_ite” anion becomes a “hypo_ous acid”, so a
  hypochlorite ion containing acid is hypochlorous acid.

Question 8

Which of the following names is incorrect?

Answer 8

K2SO3 potassium sulfate

Question 9

In naming chemical substances, when is the suffix -ous used?

Answer 9

The suffix is given to an acid in which the anion has a name ending in -ite.

Question 10

What is the correct name for Cu(HCO3 )2?

Answer 10

Cupric bicarbonate

Question 11

What is the name for the compound Cu(OH)2

Answer 11

both cupric hydroxide and copper(II) hydroxide are correct

Question 12

Which of the following best describes the compounds HNO3, HClO4, and H3PO4?

Answer 12

acids

Question 13

Which of the following best describes fluoride anion (F − )?

Answer 13

An anion

Question 14

Which of the following is a suffix used when naming cations?

Answer 14

−ium

Question 15

What are the names for the compounds

Cu(HCO3 )2 and Fe(HCO3 )3?

Answer 15

cupric bicarbonate and ferric bicarbonate

Question 16

What is the molecular formula for dinitrogen tetroxide?

Answer 16

N2O4