Slide 1 ___________________________________ 3 Elements and Compounds
___________________________________ ___________________________________ This reclining Buddha
in Thailand is made of
gold.
___________________________________ ___________________________________ ___________________________________ Foundations of College Chemistry, 14th Ed.
Morris Hein and Susan Arena
Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 2 ___________________________________ ___________________________________ Chapter Outline
3.1
___________________________________ Elements
A. Distribution of Elements
___________________________________ B. Names of the Elements
C. Symbols of the Elements
3.2
___________________________________ Introduction to the Periodic Table
A. Natural States of the Elements
___________________________________ B. Diatomic Elements
3.3
Compounds and Formulas
___________________________________ A. Molecular and Ionic Compounds
B. Writing Formulas of Compounds
___________________________________ C. Composition of Compounds
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 3 ___________________________________ Elements and Atoms
___________________________________ An element is a fundamental substance that cannot be
broken down by chemical means into a simpler substance.
___________________________________ Elements are the building blocks of matter.
___________________________________ Elements can occur naturally or be synthesized in labs.
___________________________________ The smallest unit of an element that retains its
properties and chemical behavior is called an atom.
___________________________________ Atoms are made up of subatomic particles,
but they do not have the properties of the element.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 4 ___________________________________ Elements
___________________________________ Currently, 118 elements are known.
88 of these elements are naturally occurring.
___________________________________ At room temperature,
only bromine (Br) and mercury (Hg) are liquids.
___________________________________ ___________________________________ At room temperature, 11 elements are gases:
hydrogen (H2), nitrogen (N2), oxygen (O2),
fluorine (F2), chlorine (Cl2), helium (He),
neon (Ne), argon (Ar), krypton (Kr),
xenon (Xe) and radon (Rn).
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 5 ___________________________________ ___________________________________ ___________________________________ Elements
___________________________________ Ten elements make up almost 99 % of the mass of the
Earth’s crust, seawater and atmosphere.
___________________________________ ___________________________________ ___________________________________ ___________________________________ Oxygen accounts for about 20 % of the atmosphere and
is found in nearly all rocks, sand and soil.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 6 ___________________________________ ___________________________________ Elements
___________________________________ The most prevalent elements in the human body
are oxygen (65 %), carbon (18 %) and hydrogen (10 %).
___________________________________ Some elements in the body are present in tiny amounts,
like chromium and copper, but are crucial for life.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 7 ___________________________________ Names of Elements
___________________________________ Many element names are derived from Greek, Latin or
German words that describe a property of the element.
___________________________________ Iodine comes from the Greek word iodes meaning
“violetlike” and iodine is violet colored as a vapor.
___________________________________ Some elements are named for the location of
their discovery, such as germanium which was
discovered in 1886 by a German chemist.
___________________________________ ___________________________________ Other elements commemorate famous scientists,
like curium which is named after Marie Curie.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 8 ___________________________________ ___________________________________ Symbols of the Elements
___________________________________ Each element has an abbreviation called a symbol.
Fourteen elements have single letter symbols
and the rest have two letter symbols.
iodine (I)
___________________________________ barium (Ba)
___________________________________ What element has the following symbol?
___________________________________ nitrogen
___________________________________ gold
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 9 ___________________________________ ___________________________________ Symbols of the Elements
___________________________________ The table below contains symbols
for the most common elements.
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 10 ___________________________________ Symbols of the Elements
___________________________________ The table below contains symbols
of elements derived from early names.
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 11 ___________________________________ Symbols of the Elements
___________________________________ The first letter of a symbol must always be capitalized.
If a second letter is needed, it should be lowercase.
___________________________________ Consider the element cobalt:
___________________________________ Cobalt has the symbol Co
___________________________________ Writing CO would symbolize elements C (carbon) and
O (oxygen) and would represent carbon monoxide.
___________________________________ In order to succeed in chemistry, you should work to learn
many of the elements on the periodic table.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 12 ___________________________________ ___________________________________ Introduction to the Periodic Table
___________________________________ The Periodic Table was designed by Dimitri Mendeleev
in 1869 to organize elements based on their properties.
Elements with similar chemical properties are placed
in columns called groups.
___________________________________ Four groups have special identifying names,
like Noble Gases, which are all unreactive gases.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 13 ___________________________________ Introduction to the Periodic Table
___________________________________ The eight tall columns are called representative elements,
or main group elements. These are shown in red.
___________________________________ ___________________________________ ___________________________________ ___________________________________ The elements in the center are called the transition metals.
These are shown in purple.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 14 ___________________________________ ___________________________________ Introduction to the Periodic Table
___________________________________ Elements can be further classified as metals,
metalloids and nonmetals.
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 15 ___________________________________ Metals
___________________________________ Metals are:
• solids at room temperature (except mercury)
• shiny
• good conductors of heat and electricity
• malleable (can be shaped)
• ductile (can be drawn into wires)
___________________________________ ___________________________________ Most metals have a high melting point and density.
___________________________________ Common metals include aluminum, gold, platinum,
silver, tin and iron.
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 16 ___________________________________ Metals
___________________________________ Metals readily combine with nonmetals to form
compounds but rarely combine with other metals.
___________________________________ Some metals are found in their free states,
like copper, gold and silver.
___________________________________ ___________________________________ ___________________________________ Some metals are mixed to form homogeneous mixtures
called alloys, like brass, bronze, steel and coinage metals.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 17 ___________________________________ ___________________________________ Nonmetals
Nonmetals:
• are not shiny
• have fairly low melting points and densities
• are poor conductors of heat and electricity
___________________________________ ___________________________________ Nonmetals combine with each other to form molecular
compounds and with metals to form ionic compounds.
___________________________________ Common nonmetals found naturally include carbon,
nitrogen, oxygen and sulfur.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 18 ___________________________________ Metalloids
___________________________________ Metalloids have properties between metals and nonmetals.
These elements are positioned diagonally on the
Periodic Table separating the metals and nonmetals.
___________________________________ Certain metalloids, like boron, silicon and germanium
are the materials used in electronic devices.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Let’s Practice!
19 ___________________________________ What is the symbol for silver?
a.
b.
c.
d.
e.
S
Si
Ag
Au
Sr
sulfur
silicon
silver
gold
strontium
___________________________________ ___________________________________ ___________________________________ Which of the following elements are metals?
Na, Mo, Cl, S, Mg, Pt, Kr, I, C, Cu
___________________________________ Na, Mo, Mg, Pt, Cu
Metals are typically found on the left of the Periodic Table.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 20 ___________________________________ ___________________________________ Natural States of the Elements
___________________________________ Elements tend to be reactive and combine with other
elements to form compounds.
___________________________________ It is rare to find elements in nature in their pure forms.
Gold, silver and platinum (the noble metals) have
low reactivity and are found uncombined in nature.
___________________________________ Air is composed mainly of nitrogen and oxygen,
a homogeneous mixture of diatomic elements.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 21 ___________________________________ Diatomic Elements
___________________________________ Seven elements exist as diatomic molecules.
These molecules contain exactly two atoms.
___________________________________ ___________________________________ ___________________________________ Diatomic elements can be separated.
In water (H2O), neither hydrogen or oxygen is diatomic.
___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 22 ___________________________________ Compounds and Formulas
___________________________________ A compound is a substance containing two or more
elements that are chemically combined in a
definite proportion by mass.
___________________________________ Compounds, unlike elements, can be decomposed
chemically into simpler substances.
___________________________________ ___________________________________ ___________________________________ Elements in compounds are always combined
in whole number ratios.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 23 ___________________________________ ___________________________________ Molecular and Ionic Compounds
___________________________________ Compounds fall into two general types,
molecular and ionic.
___________________________________ ___________________________________ ___________________________________ ___________________________________ Molecular compounds are held together by covalent bonds
and ionic compounds are held together by attractive
forces between the positive and negative charges.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 24 ___________________________________ ___________________________________ Molecules and Ions
___________________________________ Molecules are the smallest unchanged individual unit
of a compound formed by two or more atoms.
___________________________________ A molecule cannot be further divided
without destroying its identity.
___________________________________ Ions are charged atoms or groups of atoms.
Ions can be positively or negatively charged.
___________________________________ A positively charged ion is called a cation.
___________________________________ A negatively charged ion is called an anion.
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide ___________________________________ Compounds
25 ___________________________________ More than 50 million compounds are currently known.
Each compound has a unique set of properties.
___________________________________ Consider water (H2O) and hydrogen peroxide (H2O2).
Property
H2 O2
color
clear
pale blue
boiling point
100 °C
150 °C
___________________________________ density
1.00 g/mL
1.44 g/mL
___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 26 ___________________________________ H2O
___________________________________ ___________________________________ Writing Formulas of Compounds
___________________________________ Chemical formulas are abbreviations for compounds.
A chemical formula contains the symbols and ratio of
the atoms of the elements in a compound.
___________________________________ Consider sulfuric acid.
___________________________________ 1 molecule contains 2 H atoms, 1 S atom and 4 O atoms.
___________________________________ One possible formula for sulfuric acid is HHSOOOO.
___________________________________ A better formula is H2SO4 – “H-two-S-O-four”.
The numbers after the element symbols are subscripts.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 27 ___________________________________ ___________________________________ Writing Formulas of Compounds
1. The formula of a compound contains the symbols
of all the elements in the compound.
___________________________________ 2. When a formula contains only one atom of an element,
the number 1 is not needed as a subscript.
___________________________________ 3. When a formula contains more than one atom of an
element, the number is indicated by a subscript
written after the symbol.
___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 28 ___________________________________ Writing Formulas of Compounds
___________________________________ 4. When the formula contains more than one of a group
of atoms that occur as a unit, parentheses are placed
around the group and the number of units is
represented by a subscript outside the parentheses.
___________________________________ ___________________________________ ___________________________________ ___________________________________ 5. Formulas show the number and kind of atoms in a
compound, but not the connectivity of the elements.
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 29 ___________________________________ ___________________________________ Let’s Practice!
___________________________________ How many of each element is present in K3PO4?
3 K atoms
___________________________________ 1 P atom
___________________________________ 4 O atoms
___________________________________ How many of each element is present in Mg(OH)2?
1 Mg atom
___________________________________ 2 O atoms
2 H atoms
© 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 30 ___________________________________ ___________________________________ Composition of Compounds
___________________________________ A particular compound always contains the same
elements in the same proportions by mass no matter
what the origin.
H2O
H2O2
11.2 % H
5.9 % H
88.8 % O
94.1 % O
2H+1O
2H+2O
___________________________________ ___________________________________ ___________________________________ ___________________________________ The Law of Definite Composition states that a compound
always contains two or more elements chemically
combined in a definite proportion by mass.
© 2014 John Wiley & Sons, Inc. All rights reserved.
___________________________________ Slide 31 ___________________________________ Composition of Compounds
___________________________________ The Law of Multiple Proportions states that atoms of two
or more elements may combine in different ratios
to produce more than one compound.
___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.
Slide 32 ___________________________________ Laws and Theories
___________________________________ A law is a summary of observed behavior.
___________________________________ A theory or model is an attempt to explain
the observed behavior.
___________________________________ Laws remain constant and do not undergo modification,
while theories sometimes fail and are modified
or discarded over time.
___________________________________ ___________________________________ ___________________________________ © 2014 John Wiley & Sons, Inc. All rights reserved.