This document summarizes key concepts from Chapter 3 of a textbook on general, organic, and biochemistry. It defines elements as fundamental substances that cannot be broken down chemically, and atoms as the smallest particles of elements. It discusses the distribution of elements on Earth, how their names and symbols are derived, and how elements are arranged on the periodic table. It classifies elements as metals, nonmetals, and metalloids and notes which exist naturally as elements or diatomic molecules. It introduces compounds as combinations of elements in fixed ratios, and discusses ionic compounds, molecules, and chemical formulas.

1. Chapter 3
Elements and Compounds
This
reclining
Buddha in
the Grand
Palace in
Bangkok, T
hailand, is
made of
gold. Introduction to General, Organic, and Biochemistry 10e
John Wiley & Sons, Inc
Morris Hein, Scott Pattison, and Susan Arena

2. Chapter Outline
3.1 Elements 3.6 Elements in Their Natural
3.2 Distribution of Elements States
3.3 Names of Elements 3.7 Elements That Exist as
3.4 Symbols of the Elements Diatomic Molecules
3.5 Introduction to the Periodic 3.8 Compounds
Table 3.9 Chemical Formulas
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3. Elements
An element is …
An atom is …
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4. Elements
An element is a fundamental substance that cannot be
broken down by chemical means to simpler
substances.
There are 118 known elements.
All but 4 of the first 92 elements
occur in nature.
All elements beyond 92 except for
plutonium (94) are man made.
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5. Elements
An atom is the smallest particle of an element that can
exist.
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6. Distribution of Elements
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7. Your Turn!
The most abundant element in the earth’s crust, oceans,
and atmosphere is
A. Water
B. Hydrogen
C. Iron
D. Oxygen
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8. Distribution of Elements
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9. Names of the Elements
The names of the elements are derived from a variety of
sources:
• Iodine comes from Greek iodes, which means
violetlike.
• Bismuth comes from the German weisse masse,
which means white mass.
• Germanium was named for Germany, where it was
discovered.
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10. Symbols of the Elements
Rules for symbols of elements
1. Symbols have either one, two or three letters.
2. If one letter is used, it is capitalized.
3. If two or three letters are used, only the first is
capitalized.
N nitrogen I iodine Ni nickel
C carbon O oxygen Co cobalt
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11. Symbols of Common Elements
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12. Symbols of Elements
Derived from Early Names
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13. Introduction to the Periodic Table
Elements are arranged in order of increasing atomic
number.
Elements within a group have similar properties.
The representative elements are groups IA-VIIA and
the noble gases.
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14. Periodic Table

15. Your Turn!
The element potassium is in the first group on the
Periodic Table (group IA). Potassium is
a. an alkali metal
b. an alkaline earth metal
c. a transition element
d. a halogen
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16. Your Turn!
The elements on the periodic table are placed in order of
increasing
a. Density
b. Atomic number
c. Boiling point
d. Atomic mass
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17. Metals, Nonmetals and Metalloids
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18. Classifying Elements: Metals
Some properties of metals:
• Lustrous
• Malleable
• Conduct heat and electricity
• Ductile
• High density
• High melting point
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19. Classifying Elements: Nonmetals
Some properties of nonmetals:
• Dull (if solid)
• Brittle (if solid)
• Poor conductors of heat and electricity
• Non-Ductile
Iodine crystals
• Low density
• Low melting point
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20. Classifying Elements: Metalloids
Metalloids have properties that
are intermediate between those
of metals and those of
nonmetals.
Some are used to make the
semiconductors we need for
computer chips.
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21. Your Turn!
A solid sample of an unknown element is dull and
brittle and does not conduct heat or electricity. How
should the element be classified?
a. Metal
b. Nonmetal
c. Metalloid
d. Transition element
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22. Your Turn!
The majority of the elements are
a. Metals
b. Gases
c. Nonmetals
d. Metalloids
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23. Your Turn!
Which is not a metalloid?
a. Boron (B)
b. Silicon (Si)
c. Germanium (Ge)
d. Aluminum (Al)
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24. Elements in Their Natural States
Most elements are found as compounds in
nature because they are very reactive.
The noble metals (gold, silver and platinum)
are nonreactive and are found as elements in
nature.
The noble gases are the least reactive elements
and are found in uncombined form.
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25. Physical States of the Elements
• Most are solids at room temperature.
• Some are gases (the noble gases, nitrogen, oxygen,
fluorine and chlorine).
• Two are liquids (mercury and bromine).
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26. Elements
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27. Elements That Exist as
Diatomic Molecules
• Diatomic molecules each contain
exactly two atoms.
• There are 7 diatomic elements.
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28. Your Turn!
Which of the following is not a diatomic element?
a. Fluorine
b. Oxygen
c. Nitrogen
d. Carbon
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29. Your Turn!
Which of the following metals is not a solid at room
temperature?
a. Iron
b. Aluminum
c. Chromium
d. Calcium
e. Mercury
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30. Your Turn!
Which of the following nonmetals is not reactive?
a. Helium
b. Fluorine
c. Oxygen
d. Carbon
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31. Compounds
Compounds are composed of two or more elements
combined in a definite proportion by mass.
• Elements are always combined in whole number
ratios. Al2O3 KNO3 CaCl2
• Can be decomposed chemically into simpler
substances.
• Each compound has unique properties that are
different from the elements that make it up.
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32. Compounds
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33. Molecules
• A molecule is the smallest uncharged individual unit
of a compound.
• Usually composed of two or more nonmetals.
• Can be solids, liquids or gases.
• Do not conduct electricity.
H2O H2O2 PCl5
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34. Water
• Water molecules can be decomposed into oxygen
molecules and hydrogen molecules.
• The properties of water are very different from the
properties of oxygen gas and hydrogen gas.
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35. Your Turn!
Which of the following is not likely to be a molecule?
a. CaCl2
b. NH3
c. CO2
d. SF6
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36. Ionic Compounds
• Contain ions (charged particles).
• Compounds are held together by
the attractive forces between the
cations (positive ions) and the
anions (negative ions).
• Formulas are the simplest whole
number ratio of each element. NaCl
• Solids at room temperature.
• Conduct electricity when
molten.
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37. Sodium Chloride
The properties of sodium chloride are very different
from the properties of sodium metal and chlorine gas.
2NaCl(s) 2Na(s) + Cl2(g)
Figure 3.8 When sodium chloride (a) is decomposed,
it forms sodium metal (b) and chlorine gas (c).
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38. Your Turn!
Which of the following is true?
a. Metals form anions with negative charges.
b. Metals form anions with positive charges.
c. Metals form cations with positive charges.
d. Metals form cations with negative charges.
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39. Chemical Formulas
Specifies the number of atoms of each element in the
compound.
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40. Chemical Formulas
When the formula contains more than one of a group of
atoms that occurs as a unit, parentheses are placed
around the group and a subscript is placed to the
right of the group.
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41. Your Turn!
The formula for table sugar is C12H22O11. How many
oxygen atoms are found in a molecule of sugar?
a. 1
b. 12
c. 22
d. 11
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42. Your Turn!
Aluminum sulfate is a compound that is often found in
baking powder. How many sulfur atoms are found in
Al2(SO4)3?
a. 4 2 Al
b. 12
3*1=3S
c. 3
d. 7
3 * 4 = 12 O
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43. Your Turn!
How many hydrogen atoms are found in Al(C2H3O2)3?
a. 1
b. 9 1 Al
c. 6 3*2=6C
d. 7
3*3=9H
3*2=6O
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44. Your Turn!
The formula for ethyl alcohol is CH3CH2OH. How
many H atoms are found in a molecule of ethyl
alcohol?
a. 6 1+1=2C
b. 3
3+2+1=6H
c. 5
d. 1 1O
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45. Questions
Review Questions (pg 58)
– Do odd
– Practice later even
Paired Questions
– Do 1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41
– Practice later every other even (2, 6, etc)
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