NAMING COMPOUNDS
Lesson Objective: Distinguish between ionic and
molecular compounds, and describe the
properties of some common examples of each.
HMMM… NOT ALL SCIENTISTS WHO
CONTRIBUTE TO THE UNDERSTANDING OF
ELEMENTS ARE RECOGNIZED 
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Canadian Harriet Brooks… She studied the
radioactive element thorium, and was able to
measure what was thought to be a gas given off
by thorium.
She proved that this “gas” was in fact a new
element, and it was given the name radon.
REVIEW FROM LAST CLASS…
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Element Symbol and Name: for most elements,
the symbol is an abbreviation derived from the
element’s modern chemical name.
Symbol for silicon is Si, and the symbol for
manganese is Mn.
Some exceptions… Symbol for gold is Au, which
is from Aurum, the Latin word for gold.
NOT ALL ELEMENTS ARE NAMED FOR
LATIN WORDS.
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Some elements are named for the place they were
discovered… Californium (discovered in 1950 at
U of California).
Some are named after scientists who made
important contributions to their field of study…
Einsteinium (Albert Einstein) Fermium (Albert
Fermi), Curium (Marie Curie).
ATOMIC NUMBER
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Number above element’s symbol on the left…
shows how many protons are in the nucleus of
one atom of the element.
Oxygen atom always has 8 protons.
If you found 6 protons in an atom, which element
would you be looking at? (page 126-127)
ATOMS ARE NEUTRAL
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The number of protons equals the number of
electrons.
The atomic number also tells you how many electrons
are in an atom of a particular element.
Protons = positive
Electrons = negative
Metals- shiny, happy people… they all lose electrons
to form positive ions.
Non-metals-go all emo… they accept electrons to form
negative ions.
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Notice that the atomic number increases by one
for each element as you read across the periodic
table from left to right.
ATOMIC MASS
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Below the element’s name.
Tells you total mass of all the protons and
neutrons in an atom.
Electrons so tiny they have very little effect on
the total mass of an element.
Not all atoms of an element have the exact same
mass… different number of neutrons from atom
to atom.
AMU
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Atomic mass is measured by atomic mass unit
(amu)
Defined as 1/12 the mass of a carbon-12 atom.
Mass number: represents the sum of the number
of protons and neutrons in an atom.
PATTERNS:
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Alkali Metals (group 1, not including hydrogen):
Most reactive of the metals; react when exposed
to air or water. As you move down the group,
reactivity increases.
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Alkaline-earth metals (group 2): react to air and
water as well, but reactivity not as strong as that
of the alkali metals.
HALOGENS (GROUP 17)
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Most reactive non-metals.
Chlorine… Bromine (gas so corrosive can burn
skin).
Elements in this group can combine with other
elements to form substances with useful
properties: Sodium + Fluorine = Sodium Fuloride
(chemical found in toothpaste).
NOBLE GASSES (GROUP 18)
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Most stable and un-reactive elements… “inert”.
Long thought that they could NEVER combine
with other elements.
1962, Canadian Chemist, Neil Bartlett &
colleagues at U of BC synthesized the first noble
gas compound containing xenon, platinum, and
fluorine.
REMEMBER FROM YOUR TIMELINE…
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Atom comes from the Greek word atomos which
means indivisible… People once thought the
atom was the smallest particle possible.
Today we know that the atom is made of several
much smaller particles.
COMBINING ELEMENTS TO MAKE
COMPOUNDS.
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Water, soap, shampoo, toothpaste, ammonia,
bleach, salt, baking soda, baking powder… all
chemicals.
Each of these compounds has a chemical name
and a chemical formula.
The formula identifies which elements, and how
much of each are in the compound.
TABLE SALT
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Chemical Name: Sodium Chloride
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Chemical Formula: NaCl
BAKING SODA
Chemical Name: Sodium Bicarbonate
Chemical Formula: NaHCO3
NOMENCLATURE
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Rules for naming compounds.
Until the 18th century, no standardized system for
naming chemicals existed.
Created confusion as chemical names varied from
country to country, and scientist to scientist.
For example, hydrochloric acid and muriatic acid are
the same thing/chemical.
Some compounds are better known by their common
name: Bleach VS Aqueous Sodium Hypochlorite?
1787, GUYTON DE MORVEAU
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Created a naming system, or nomenclature, for
compounds.
He decided to use the chemical name for each
element in the compound, always putting the
metal element first.
Zinc + Oxygen = Zinc Oxide
1920, IUPAC
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International Union of Pure and Applied
Chemistry… Is the body responsible for agreeing
on the appropriate name for every chemical
compound discovered.
http://www.iupac.org/
IF YOU KNOW ONLY THE FORMULA OF A
CHEMICAL COMPOUND, YOU CAN DETERMINE
ITS CHEMICAL NAME.
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If you know only its name… You can determine
its chemical formula.
Sodium Chloride… Indicates the compound is
made of one atom of sodium, and one atom of
chlorine.
Chemical Formula… NaCl, indicates this too.
WATER: H20
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Next to the H is a subscript (sub means below).
The 2 indicates there are two atoms of hydrogen
to go with every atom of oxygen.
Subscript numbers in a chemical formula
indicate the number of atoms of the elements
that must combine to form the compound.
No subscript number indicates that only one
atom of that element is needed.
INDICATING THE PHYSICAL STATE OF A
COMPOUND:
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State of chemical at room temperature?
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H2O (l) – the “2” and the “l” are subscripts
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NaCl (s)
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NaCl (aq)?
IONIC COMPOUNDS
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Table salt is formed when a very reactive metalsodium- is placed in a container with a poisonous,
green non-metal, chlorine gas.
When the two chemical elements are combined,
the sodium metal explodes in a bright yellow
flame.
As the sodium burns, a white, course powder is
produced… Salt or Sodium Chloride NaCl (s)
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Sodium Chloride is an ionic compound.
Ionic compounds are pure substances formed as
the result of the attraction between particles of
opposite charges, called ions.
Table salt is formed from positively charged
sodium ions and negatively charged chorine ions.
OTHER PROPERTIES OF IONIC COMPOUNDS:
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High melting point.
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Good electrical conductivity.
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Distinct crystal shape.
ALL IONIC COMPOUNDS ARE SOLID AT
ROOM TEMPERATURE.
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Table salt will not melt until it is heated to
801degrees Celcius.
When an ionic compound is melted or dissolved in
water, it will conduct electricity.
This property of ionic compounds led to the study
of electrochemical cells (cells that convert
chemical energy into electrical energy or vice
versa)… And eventually to the invention of
batteries.
IONS
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When an ionic compound is dissolved in water,
the metal and non-metal form an aqueous
solution of ions.
An ion is an atom, or group of atoms that has
become electrically charged through the loss or
gain of electrons.
Review chart on page 146 in text.
ION CHARGES
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To indicate ions, us a plus sign (+) or a minus
sign (-)
Na+ (superscript… means “above”) and ClPolyatomic ions: poly means many. Polyatomic
ions are a group of atoms acting as one.
E.g. One atom of Carbon and three atoms of
Oxygen form the polyatomic ion called carbonate
or CO3 2-
NAMING IONIC COMPOUNDS
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2 rules to remember.
First: The chemical name of the metal or positive
ion goes first, followed by the name of the nonmetal or negative ion.
Second: The name of the non-metal negative ion
changes its ending to ide.
NaCl is not sodium chlorine, but sodium chloride.
ONE EXCEPTION TO THESE NAMING RULES
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Where negative ions are polyatomic ions, the
name remains unchanged.
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Calcium carbonate, not Calcium carbonide.
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CaCO3
ION CHARGE CHART, PAGE 146
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Some elements have more than one ion charge.
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Iron… 2+ or 3+
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Show clearly which ion is being used in a
chemical name.
Iron Oxide: Fe2+O
USING ION CHARGES AND CHEMICAL
NAMES TO WRITE FORMULAS (PAGE 126)
Step 1: Print the metal element’s symbol with its
ion charge (remember that the ion charge is
found in the top right hand corner).
 Next to it, print the non-metal element’s symbol
with its ion charge.
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Ca2+ Cl1-
Step 2: Balance the ion charges. The positive ion
charge must balance the negative ion charges.
 In our example, this means that there must be 2
chlorine atoms each with an ion charge of 1- to
balance the 2+ ion charge of one calcium atom.
Now you know how many of each element you
need to include in the formula.
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Ca2+ Cl1- Cl1-
Step 3: Write the formula by indicating how
many atoms of each element are in it as shown.
Do not include the ion charge in the in the
formula.
 Place the number of atoms of each element in a
subscript after the element’s symbol. If there is
one atom, no number (subscript) is used.
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CaCl2(s)
ION CHARGES AND THE PERIODIC TABLE
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Take another look at the periodic table on pages
126/127.
Do you see a pattern in the ion charges?
Group 1, Alkali metals, have an ion charge of 1+
 Group 17, Halogens, have an ion charge of 1
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Generally, all the elements in a group form ions
with the same charge. Pattern is most consistent
at extreme ends of the periodic table… A little
iffy in the middle! Look at
STILL LOOKING AT THE PERIODIC TABLE
ON PAGES 126/127…
Write the formula for:
Lithium oxide
Iron(III) cloride
Copper(II) phosphide
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Write the chemical name for:
AlBr3(s)
PbS2(s)
Fe2O3(s)
Li2O(s)
 FeCl3(s)
 Cu3P2(s)
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Aluminum bromide
 Lead(IV) sulfide
 Iron(III) oxide
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MOLECULAR COMPOUNDS
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Scientists have discovered more than 10 million
compounds. At least 9 million are molecular
compounds containing carbon… We are a carbonbased life form, and most molecules from living
systems contain carbon.
WHEN NON-METALS COMBINE, A PURE
SUBSTANCE CALLED A MOLECULE
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Or molecular compound is formed.
Molecular compounds differ from ionic
compounds in several ways:
They can be solids, liquids, or gases at room temp
(recall that ALL ionic compounds are solid at
room temp).
They are usually insulators, and are poor
conductors of electricity (recall that an ionic
compound melted or dissolved in water will
conduct electricity).
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They have relatively low melting and boiling
points because the forces between the molecules
are weak.
Examples of molecular compounds include sugar,
acetylene, and water.
WRITING FORMULAS FOR MOLECULAR
COMPOUNDS
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It is hard to predict how non-metals combine…
there are no ions present and the ion charge is
not used in the formula.
The formulas for molecular compounds still
clearly show what elements are present, and how
many of each type of element make up the
molecule.
E.g. Ammonia: NH3(g)
NAMING OF MOLECULAR COMPOUNDS
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All molecular compounds, except those
containing hydrogen, can be named using the
following rules:
(common names are used for molecular
compounds containing hydrogen… water,
ammonia, etc.)
1.
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The first element in the compound uses the
element name- just like ionic compounds.
2.
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The second element in the compound uses the
suffix “ide” – just like ionic compounds.
3.
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When there is more than one atom in the
formula, a prefix is used which specifies the
number of atoms.
4.
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An exception to rule 3 is when the first element
has only one atom, the prefix mono is not used.
SO… PREFIX + FIRST ELEMENT/PREFIX +
SECOND ELEMENT (ENDING IN “IDE”)
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CO2
carbon dioxide
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N 2O
dinitrogen monoxide
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N 2O 3
dinitrogen trioxide
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NF3
nitrogen trifluoride
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CCl4
carbon tetrachloride
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PF5
phosphorus pentafluoride