Chemical Formulas and Compounds

Flashcards about chemical forumlas and compounds

What do chemical formulas represent?

The ratios of atoms in a chemical compound

What are the systematic methods chemists use?

Naming compounds and writing chemical formulas

What does a chemical formula indicate?

The relative number of atoms of each kind in a chemical compound

What does the chemical formula reveal for a molecular compound?

The number of atoms of each element contained in a single molecule of the compound

What does the chemical formula represent for an ionic compound?

One formula unit—the simplest ratio of the compound’s positive ions (cations) and its negative ions (anions).

What are monatomic ions?

Ions formed from a single atom

How are monatomic cations identified?

Simply by the element’s name

How are monatomic anions named?

The ending of the element’s name is dropped, and the ending -ide is added to the root name

What are binary compounds?

Compounds composed of two elements

What must be equal in a binary ionic compound?

The total numbers of positive charges and negative charges

What is nomenclature?

A naming system; combining the names of the compound’s positive and negative ions

What is the Stock system of nomenclature?

It uses a Roman numeral to indicate an ion’s charge, placed in parentheses immediately after the metal name.

What are oxyanions?

Polyatomic ions that contain oxygen

What ending is used for the ion name with the greater number of oxygen atoms?

-ate

What ending is used for the ion name with the lesser number of oxygen atoms?

-ite

What prefix is given to an anion that has one fewer oxygen atom than the -ite anion?

hypo-

What prefix is given to an anion that has one more oxygen atom than the -ate anion?

per-

What is the Stock system for naming molecular compounds based on?

Oxidation numbers

What is the old system of naming molecular compounds based on?

The use of prefixes

Define acid.

A distinct type of molecular compound; most acids used in the laboratory can be classified as either binary acids or oxyacids.

Define salt.

An ionic compound composed of a cation and the anion from an acid

What are oxidation numbers?

Also called oxidation states, indicate the general distribution of electrons among the bonded atoms in a molecular compound or a polyatomic ion.

What is the general rule in assigning oxidation numbers?

Shared electrons are assumed to belong to the more-electronegative atom in each bond.

What is the oxidation number of atoms in a pure element?

Zero

What is the oxidation number of fluorine in all of its compounds?

-1

What is the oxidation number of oxygen in almost all compounds?

-2

What is the oxidation number of hydrogen in all compounds containing elements that are more electronegative than it?

+1

What is the molar mass?

The mass in grams of one mole, or approximately 6.022 × 1023 particles, of the substance

What is percentage composition?

The mass percentage of each element in a compound

What is an empirical formula?

Consists of the symbols for the elements combined in a compound, with subscripts showing the smallest whole-number mole ratio of the different atoms in the compound.

What is the molecular formula?

The actual formula of a molecular compound