Naming Ionic Compounds

Report
Sec. 2.2 Part A
Science 10
NAMING IONIC COMPOUNDS
REVIEW
How do atoms form ions?
 Why do they want to form ions?
 What are positively charged ions called?
Negatively charged ions?
 What can occur once ions have been created?
 Why does this occur?

OBJECTIVES
explain why the IUPAC system of naming
compounds is important
 describe the process of ionic bonding and give
examples of ionic compounds
 give correct names and formulas for ionic
compounds, using the periodic table, table of
ions and IUPAC rules

IUPAC AND COMPOUND NAMING
IUPAC – International Union of Pure and
Applied Chemistry
 Responsible for naming compounds
 Allows consistent way of naming compounds
 Why is this important?

 Allows
for clear and precise communication
IONIC COMPOUNDS

How do we form ionic compounds?
 Transfer
of electrons between atoms
 Metal and non-metal

Transfer of electrons creates full outer energy
levels
 More
stable
 Attraction of ions called ionic bonding
IONIC COMPOUNDS

Practice: Give drawings and show electron
transfer for the following atoms:
 Sodium
 Magnesium
 Chlorine
 Oxygen
NAMING IONIC COMPOUNDS: THE RULES
Two part name: cation and anion
 1) name cation first with element’s name
 2) name anion second with first part of name
and change last part to “ide”
 Ex. Sodium chloride (sodium ion and chloride
ion)
 IMPORTANT: always write names of elements as
lower case (unless at beginning of sentence)

PRACTICE

Name the following compounds:
 MgO
 BaF2(s)
 K3N(s)
FORMULAS FOR IONIC COMPOUNDS
Contains element symbols
 Some have subscripts

 Ex.

BaF2(s)
What this means:
 One

barium ion for every two fluoride ions
Ionic compounds are neutral
 Therefore,
need to have enough of each atom to
cancel the charges out
FORMULAS FOR IONIC COMPOUNDS

What are the charges for each ion in this
compound?
 Sodium
chloride
How many of each ion do we need to cancel the
charges out?
 How about this one?

 Magnesium
chloride
 How many do we need?
 These make the subscripts!
STEPS FOR WRITING FORMULAS
Steps
Example
Example
Sodium chloride
Aluminium chloride
Identify ions and charges
sodium: Na+
chloride: Cl-
aluminium: Al3+
chloride: Cl-
Determine total charges needed
to balance
Na+ : 1
Cl- : 1
Al3+ : 3
Cl- : 1+1+1=3
Note the ratio of cations to
anions
1 to 1
1 to 3
Use subscripts to write formula
NaCl
AlCl3
If the ratio is 1:1, do not need to include subscripts
The subscripts should be the simplest form
What does this mean?
Formula unit- name for ionic compound unit (NEUTRAL)
LOWEST COMMON MULTIPLE

When charges are not easy to balance:
 i.e.
calcium nitride
 Ca2+ and N3 Find the lowest common multiple to balance the
charges
 What is the lowest common multiple here?
 Simplify!!! What do you end up with?
BALANCING CHARGES
Need to balance the charges
i.e. one positive charge balances out one negative
charge
Why do we need to balance the charges? What
happens to our compounds when we do this?
PRACTICE

Write the formulas/names for the following
compounds:
 sodium
bromide
 calcium nitride
 magnesium oxide
 aluminium chloride
 MgS
 AlN
 Li3P
MULTIVALENT ELEMENTS

Some metals have more than one stable ion


To indicate which ion it is, use Roman numerals in
names


Ex. Iron has two stable ions: Fe2+ and Fe3+.
Example: iron (II) or iron (III)
Still use subscripts for compounds- be careful
about which ion it is!
Ex. FeBr2 = iron (II) bromide
 Ex. FeBr3


Only use Roman numerals when more than one
ion (ONLY for transition metals)
PRACTICE

Write formulas for following:
 copper
(I) nitride
 lead (IV) chloride
 nickel (III) oxide

Write the names for the following formulas:
 AuN
 CrO
 TiBr4
Sec A2.2 Part B
Science 10
NAMING IONIC AND MOLECULAR
COMPOUNDS
REVIEW
How does an ionic compound form?
 What name would you give for the following?

 MgCl2
 LiBr
 K3N
 FeCl3
OBJECTIVES
predict formulas and write names for ionic
compounds with polyatomic ions
 describe covalent bonding in molecular
compounds
 identify diatomic/polyatomic molecular
elements
 give correct names and formulas for molecular
compounds with and without hydrogen using
periodic table and IUPAC rules

POLYATOMIC IONS
Polyatomic ions- ions made of several nonmetallic atoms
 Come as one “unit” (consider to be one unit
when naming)
 List in periodic table of polyatomic ions with
symbol and charge
 Ending usually “-ate” (more oxygen) or “-ite”
(less oxygen)

NAMING WITH POLYATOMIC IONS
Cation + anion
 DO NOT change the ending of a polyatomic ion
 Practice:
 Au(NO3)3(s)
 (NH4)3PO4(s)
 K2Cr2O7(s)

WRITING FORMULAS

Same method with exception:
 Subscripts
for polyatomic ions placed in brackets
 Ex. Fe2(SO4)3
 Put
3 outside brackets because there are 3 SO42- for
each Fe3+
Practice:
 barium hydroxide
 iron (III) carbonate
 copper (I) permanganate

MOLECULAR COMPOUNDS
Molecule: two or more non-metal atoms
bonding
 Can be same or different atoms
 Fixed numbers of bonded atoms (unlike ionic
compounds: formula unit= part of crystal
lattice)

COVALENT BONDS
How molecular compounds bond
 Atoms share electrons (no transfer)
 Pair of shared electrons makes one covalent bond
 Allows outer energy levels to be filled
 Can share more than one pair of electrons (double
or triple bonds)
 http://www.youtube.com/watch?v=QqjcCvzWwww

MOLECULAR ELEMENTS
Elements that form own molecules (ex. O2)
 Diatomic- molecule made of 2 of the same
atom

 H2,

N2, O2, F2, Cl2, Br2, I2.
Polyatomic- More than two of the same atom
 O3,
P4, S8.
Only appear as these when by themselves
 Should memorize these!

NAMING MOLECULAR COMPOUNDS WITHOUT
HYDROGEN


For binary compounds (two elements)
Use Greek prefixes:

What are they for numbers 1-10?

Indicates how many of each atom

Prefix + first element followed by prefix + second element ending in
“-ide”





Ex.
N2O (dinitrogen monoxide)
PBr3
CO
CS2
PRACTICE
Write the names or formulas for the following:
 CO2(g)
 N2O(g)
 PCl3(g)
 oxygen difluoride
 dinitrogen tetrasulfide
 sulfur trioxide

NAMING MOLECULAR COMPOUNDS WITH
HYDROGEN
Often given names
 Ex. “water” official IUPAC name for H2O
 Table A2.12 (Be familiar with this chart! Should
know the important ones/ones you will see
most often)

HOW DO WE TELL THE DIFFERENCE?

Go through difference between ionic and
molecular compounds
 How
do we know which is which and when to use
what naming rules (dichotomous key)

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