2. + =
Na Cl NaCl
A compound is a pure substance made up ofA compound is a pure substance made up of
COMPOUNDSCOMPOUNDS
are chemically combinedare chemically combined
two or more elements in which the elementstwo or more elements in which the elements
3. There are two types
of compounds:
COMPOUNDSCOMPOUNDS
ionicionic
molecularmolecular
&
4. An ion is an atom or group of atoms
that has either a positive charge or
a negative charge
IONIC COMPOUNDSIONIC COMPOUNDS
5. IONIC COMPOUNDSIONIC COMPOUNDS
An ionic compound is formed fromAn ionic compound is formed from
one or more positively charged ionsone or more positively charged ions
and one or more negatively charged
ions
and one or more negatively charged
ions
6. IONIC COMPOUNDS
IONIC COMPOUNDS
Ions form when atoms of differentIons form when atoms of different
elements combine by transferring electronselements combine by transferring electrons
from one atom to anotherfrom one atom to another
7. + =
Na Cl NaCl
For example, this process occurs when atoms of
sodium metal (Na) combine with atoms of chlorine
(Cl) to form sodium chloride (NaCl), or table salt
IONIC COMPOUNDS
IONIC COMPOUNDS
8. During the formation of NaCl, one electronDuring the formation of NaCl, one electron
is transferred from a sodium atomis transferred from a sodium atom
to a chlorine atomto a chlorine atom
IONIC COMPOUNDSIONIC COMPOUNDS
9. Each sodium atom loses one electron andEach sodium atom loses one electron and
IONIC COMPOUNDS
IONIC COMPOUNDS
becomes a positively charged ion Na+becomes a positively charged ion Na+
Na+
10. The symbol “+” is written as a superscriptThe symbol “+” is written as a superscript
IONIC COMPOUNDS
IONIC COMPOUNDS
to indicate that the sodium has a charge of 1+to indicate that the sodium has a charge of 1+
Na+
11. Cl-
Each chlorine atom gains one electronEach chlorine atom gains one electron
IONIC COMPOUNDS
IONIC COMPOUNDS
to become a negatively charged ion Cl-to become a negatively charged ion Cl-
12. The symbol “-” is written as a superscript toThe symbol “-” is written as a superscript to
indicate that the chlorine ion has a charge of 1-indicate that the chlorine ion has a charge of 1-
Cl-
IONIC COMPOUNDS
IONIC COMPOUNDS
13. Notice that both ions have 8 electrons inNotice that both ions have 8 electrons in
their outermost shelltheir outermost shell
IONIC COMPOUNDSIONIC COMPOUNDS
14. Ions often form so that the outer shell is full,Ions often form so that the outer shell is full,
or contains the maximum number of electrons
or contains the maximum number of electrons
IONIC COMPOUNDSIONIC COMPOUNDS
15. Metal atoms tend to lose electronsMetal atoms tend to lose electrons
Non-metal atoms tend to gain electronsNon-metal atoms tend to gain electrons
IONIC COMPOUNDSIONIC COMPOUNDS
16. When an atom gives up one or moreWhen an atom gives up one or more
electrons it becomes positiveelectrons it becomes positive
called a cation (“cat-eye-on”)called a cation (“cat-eye-on”)
17. When an atom gains one or moreWhen an atom gains one or more
electrons it becomes negativeelectrons it becomes negative
called an anion (“an-eye-on”)called an anion (“an-eye-on”)
19. The farther the valence electron is from its
The farther the valence electron is from its
positive nucleus, the more easily it is removedpositive nucleus, the more easily it is removed
and the more reactive the atom isand the more reactive the atom is
20. Reactivity generally increases for cations as
you move down the periodic table
ex.) potassium is more reactive than sodium
CATIONSCATIONS
LithiumLithium
SodiumSodium
PotassiumPotassium RubidiumRubidium
CesiumCesium
22. Reactivity generally decreases for anions as
you move down the periodic table
ex.) fluorine is more reactive than chlorine
FluorineFluorine BromineBromine IodineIodine
AstatineAstatine
ANIONSANIONS
ChlorineChlorine
25. At room temperature, most are hard,At room temperature, most are hard,
IONIC COMPOUNDSIONIC COMPOUNDS
brittle solids that can be crushedbrittle solids that can be crushed
26. Ionic compounds form crystals that have an
alternating arrangement of positively charged
ions and negatively charged ions, so that when
they break their edges are well-defined
IONIC COMPOUNDSIONIC COMPOUNDS
27. IONIC COMPOUNDSIONIC COMPOUNDS
In an ionic crystal, every ion is attracted to
every other ion in the crystal. As a result,
ionic crystals have very high melting points
ex.) NaCl melts at 800o
C
28. When an ionic compound
dissolves in water, the crystal
structure breaks down and the
ions become free to move.
IONIC COMPOUNDSIONIC COMPOUNDS
29. Solutions of ionic compounds canSolutions of ionic compounds can
IONIC COMPOUNDSIONIC COMPOUNDS
conduct electricityconduct electricity
30. A cation will react with an anion in orderA cation will react with an anion in order
to acquire a full valence shellto acquire a full valence shell
31. When a cation reacts with an anion the new
arrangement of valence electrons has less
energy than the previous arrangement
IONIC COMPOUNDSIONIC COMPOUNDS
32. For many atoms, this arrangement resembles theFor many atoms, this arrangement resembles the
noble gas that is closest on the periodic tablenoble gas that is closest on the periodic table
33. A metal cation will have the same number of
electrons as an atom of the closest noble gas
with a lower atomic number
CATIONSCATIONS
34. For example, neon is the closest noble
gas in the periodic table to sodium,
magnesium and aluminum
CATIONSCATIONS
35. The cations Na+
, Mg2+
, and Al3+
all have the
same number of electrons as atoms of neon
CATIONSCATIONS
Na
11p
12n
+1
Al
13p
14n
+3
Mg
12p
12n
+2 Ne
10p
10n
36. Things to remember:
• Not all atoms will form ions
• Some atoms can form an ion in more
than one way
• Information on the periodic table will
show you the ion charges for each
element
IONIC COMPOUNDSIONIC COMPOUNDS
37. • To write the symbol for an ion, write the
symbol of the element and show the
ion charge as a superscript
• ex.) the symbol of a calcium ion is Ca2+
• When an ion has a charge of 1+ or 1-
the symbol has no number in the
superscript, such as Na+
or F-
ION SYMBOLSION SYMBOLS
38. When an element can
form only one type of ion,
the ion has the same
name as the element
ex.) Ca2+
= “calcium”
ION NAMESION NAMES
Ca
20p
20n
+2
39. A multivalent element
is an element that can
form an ion in more
than one way
ex.) An atom of copper
can form two different
ions: Cu+
or Cu2+
ION NAMESION NAMES
40. The name of an ion of a multivalent element
always contains a Roman numeral that
indicates the ion charge
ION NAMESION NAMES
41. • For example, Cu+
is named copper(I)
(read as “copper one”)
• Cu2+
is named copper(II) (read as
“copper two”)
• Only multivalent metals have Roman
numerals in their names
ION NAMESION NAMES
42. 1. Name the metal ion first
The name of the metal ion is the
same as the element name
ex.) in KBr, the name of the K+
ion
is potassium
If the element can form an ion in
more than one way, include a
Roman numeral to indicate charge
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
K
19p
20n
+1
43. 2. Name the non-metal ion second
– When a non-metal becomes
a negative ion, the ending of
its name changes to “ide”
– ex.) a bromine atom (Br)
gains an electron to become
a bromide ion (Br-
)
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
45. 3. Name the ionic compound by
combining the ion names
The name of KBr is therefore
“potassium bromide”
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
46. • The formulas of ionic compounds
often contain numbers called
subscripts - ex.) Na3P
• If the metal forms only one type of ion,
the subscript can be ignored when
determining the name
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
47. • Although ionic compounds are made
of charged particles, the compound
itself has no net charge
• All ion charges of an ionic compound
must add up to zero
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
48. The positive and negative charges in an
ionic compound must be equal
RULE:RULE:
49. Example Problem 1:
Write the name of the ionic compound ZnF2
1. Name the metal ion: Zn forms only one
type of ion (Zn2+
), so the name is zinc
2. Name the non-metal ion: The atom is
fluorine so the ion is fluoride
3. Combine the names: zinc fluoride
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
50. Example Problem 2:
Write the name of the ionic compound TiI4
1. Identify the ions that form the compound:
Ti4+
and I-
2. Name the metal ion: the ion has a 4+
charge, so the name is titanium(IV)
3. Name the non-metal ion: the name of the
atom is iodine, so the ion is iodide
4. Combine the names: titanium(IV) iodide
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
51. A polyatomic ion is a
group of atoms, usually of
different elements, that
act as a single ion
ex.) one atom of sulphur
and four atoms of oxygen
form the polyatomic ion
called sulphate, or SO4
2-
POLYATOMIC IONSPOLYATOMIC IONS
52. • Similar polyatomic ions are named
using the suffixes “-ate” or “-ite”
• ex.) NO3
-
is nitrate; NO2
-
is nitrite
• Most common polyatomic ions have a
negative charge
• However, the ammonium
ion NH4
+
has a positive
charge
POLYATOMIC IONSPOLYATOMIC IONS
54. Example Problem 3:
Write the name of the ionic compound LiHCO3
1. Name the metal/positive ion:
Li+
= lithium
2. Identify the polyatomic ion (use table):
HCO3
-
= hydrogen carbonate
3. Combine the names:
lithium hydrogen carbonate
NAMING IONIC COMPOUNDSNAMING IONIC COMPOUNDS
