Ch 6 Section 3 Flashcards
A familiar example of an ionically bonded compound is
Sodium chloride
A sodium atom, NA+ has a charge of
1+
A chloride ion, Cl- has a charge of
1-
There is an electrical force of attraction between
Oppositely charged ions
In sodium chloride the oppositely charged ions combine in a one to one ratio so that each positive charge is
Balanced by a negative charge
An ionic compound is composed of positive and negative ions that are
Combined so that the numbers of positive and negative charges are equal
Most ionic compounds exist as
Crystalline solids
A crystal of any ionic compound is a 3-dimensional network of
Positive and negative ions mutually attracted to one another
In contrast to a molecular compound an ionic compound is not composed of
Independent neutral units that can be isolated and examine s
The chemical formula of an ionic compound merely represents the
Simplest ratio is the compounds combined ions that gives electrical neutrality
The chemical formula of an ionic compound shows the ratio of the i
Ions present in a sample of any size
A formula unit is the simplest collection of atoms from which an
Ionic compounds formula can be established
In the naming of a monatomic anion the ending of the elements name is replaced with
-ide
Most of the rocks and minerals that make up earths crust consist of
Positive and negative ions held together by ionic bonding
The ratio of ions in a formula unit depends on the
Charles of the ions combined
Electron for notation can be used to demonstrate the
Changes that take place in ionic bonding
Ionic compounds do not ordinarily form by the
Combination of isolated atoms
Atoms it sodium and other alkali metals readily lose one electron to
Form cations
Atoms of chlorine and other halogens readily gain one electron to
Form anions
The combination of sodium and chlorine atoms to produce one formula unit of sodium chloride can be represented as follows
Sodium atom + chlorine atom –> sodium cation + chlorine anion
(Refer to txtbk for electron dot notation)
The transfer of an electron from the sodium atom to the chlorine atom transforms each atom into an ion with a
Noble gas configuration
In an ionic crystal ions minimize their potential energy by combining in an
Orderly arrangement known as a crystal lattice
The attractive forces at work within an ionic crystal include those between
Oppositely charged and those between the nuclei and electrons of adjacent ions
The repulsive forces at work within an ionic crystal include those between
Like-charged ions and those between electrons of adjacent ions
The distances between ions and their arrangement in a crystal represent a
Balance among all these forced
In NaCl attraction between the adjacent oppositely charged ions is much stronger than
Repulsion by other ions or the same charge which are farther away
The 3-dimensional arrangements of ions and the strength of attraction between them vary with the
Sizes and charges of the hind and the numbers of ions of different charges
To compare bond strengths in ionic compounds chemists compare the amounts of energy
Releases when separated ions in a gas come together to form a crystalline solid
Lattice energy is the energy released when one
Nike of an ionic crystalline compound is formed from gaseous ions
The negative lattice energy values indicate that energy is
Released when the crystals are formed
The force that holds ions together in ionic compound is a very strong overall
Attraction. Between positive and negative charges
The forces of attraction between molecules are much… Than the forces among formula…
Weaker than the forces among formula units in ionic bonding
This difference in the strength of attraction between the basic units of molecular and ionic compounds gives rise to
Different properties in the two types or compounds
The melting pt, boiling pt, and harness of a compound depend on how
Strongly it’s basic units are attracted to each other
Because the forces of attraction between individual molecules are not very strong many molecular compounds melt at
Low temperatures
Many molecular compounds are completely…. At room temperature
Gaseous
The ions in ionic compounds are held together by strong attractive forced do ionic compounds generally have higher
Melting and boiling points than do molecular compounds
Ionic compounds are hard but
Brittle
In an ionic crystal even a slight shift of one town of ions relative to another causes a large
Buildup of repulsive forces
These repulsive forces in the ionic crystals make it difficult for one layer to move
Relative to another, causing ionic compounds to be hard
If one layer is moved, however, the repulsive forces make the layers part
Completely, causing ionic compounds to be brittle
In the solid state, ions cannot move, so the compounds are not
Electrical conductors
In the solid state, ions cannot move, so the compounds are not
Electrical conductors
In the molten state, ionic compounds are electrical conductors because the ions can move
Freely to carry electrical current
Many ionic compounds can…in water
Dissolve
When ionic compounds dissolve their ions separate from each other and become
Surrounded by water molecules
These ions are free to move through the solution so sucks solutions are
Electrical conductors
Other ionic compounds do not dissolve in water, however, because the attractions between the water molecules and the ions cannot overcome the
Attraction. Between the ions
Certain aims bond covalently with each other to form a group of atoms that has both
Molecular and ionic characteristics
A poly atomic ion is a charged group of
Covalently bonded atoms
Poly atomic ions combine with ions of opposite charge to form
Ionic compounds
The charge of a poly atomic ion results from an excess of
Electrons (negative charge) or a shortage of electrons (positive charge)
If the ion is negatively charged add to the total number of cal me electrons a number of electrons corresponding to the
Ions negative charge
If the ion is positively charged, subtract from the total number of valence electrons s number of the electrons corresponding not to the ions
Positive charge
