1. Northern Kentucky University
Lecture Presentation
Chapter 3
Elements of Chemistry
Bradley Sieve
Northern Kentucky University
Highland Heights, KY
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2. 3.1 Matter Has Physical and Chemical Properties
Physical Properties
Can change with surrounding conditions
Ice melting or freezing
Include appearance, density, and phase
Physical changes do not change the chemical identity
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3. 3.1 Matter Has Physical and Chemical Properties
Physical Properties
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4. 3.1 Matter Has Physical and Chemical Properties
Physical Changes
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5. Concept Check The melting of gold is a physical change. Why?
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6. Concept Check
During a physical change, a substance changes only one or more of its physical properties; its chemical identity does not change. Because melted gold is still gold but in a different form, its melting is only a physical change.
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7. 3.1 Matter Has Physical and Chemical Properties
Characterize the ability of a substance to react or transform to a new substance
Methane (CH4) is burned, forming CO2 and H2O
Chemical Changes
Do change the chemical identity of the substance
Involve the rearrangement of atomic bonding
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8. 3.1 Matter Has Physical and Chemical Properties
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9. 3.1 Matter Has Physical and Chemical Properties
Chemical Bond
The force of attraction between atoms
Are changed during chemical changes
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10. 3.1 Matter Has Physical and Chemical Properties
Chemical reaction
Means the same thing as chemical change
Materials undergoing change are said to
be reacting
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11. Concept Check
Each sphere in the following diagrams represents an atom. Joined spheres represent molecules. One set of diagrams shows a physical change, and the other shows a chemical change. Which
is which?
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12. Concept Check
In set A, the molecules before and after the change are the same. They differ only in their positions. Set A, therefore, represents only a physical change. In set B, new molecules, consisting of bonded red and blue spheres, appear after the change. These molecules represent a new material, so set B represents a chemical change.
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13. 3.1 Matter Has Physical and Chemical Properties
Distinguishing Physical and Chemical Changes
Physical changes can be reversed easily
Chemical changes form a new set of materials different from the original material
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14. 3.1 Matter Has Physical and Chemical Properties
Would this sequence show a physical or chemical change?
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15. 3.1 Matter Has Physical and Chemical Properties
Would this sequence show a physical or chemical change?
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16. 3.2 Elements Are Made of Atoms
Atoms are the basic building block of
all matter
Roughly 100 different types
About 90 are found in nature
The way atoms combine leads to the great variety of substances
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17. 3.2 Elements Are Made of Atoms
Made up of a single
atom type
Listed on the periodic
table of elements
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18. 3.2 Elements Are Made of Atoms
Periodic Table
Organizes the known elements
Shows the atomic symbol for each element
Comprised of one or two letters related to the name
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19. 3.2 Elements Are Made of Atoms
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20. 3.2 Elements Are Made of Atoms
Elemental Formula
Used to show number of atoms in molecules of elements
N2 is two nitrogen atoms in one molecule
Elements containing individual atoms simply list the symbol (C, Au)
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21. 3.3 The Periodic Table Helps Us to Understand the Elements
Organization in the periodic table
Metals are
On the left of the periodic table
Shiny, malleable, and good conductors
Nonmetals
On the right of the periodic table
Poor conductors, dull, and brittle
Metalloids
Sit between metals and nonmetals
Have both metallic and nonmetallic properties
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22. 3.3 The Periodic Table Helps Us to Understand the Elements
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23. 3.3 The Periodic Table Helps Us to Understand the Elements
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24. 3.3 The Periodic Table Helps Us to Understand the Elements
Periods
Are horizontal rows across the periodic table
Exhibit periodic trends across
Atomic size decreases as you move to the right
Repeating trend is called periodicity
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25. 3.3 The Periodic Table Helps Us to Understand the Elements
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26. Concept Check
Which are larger: atoms of cesium, Cs (number 55), or atoms of radon, Rn
(number 86)?
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27. Concept Check
Cesium is positioned at the far left of period 6, and you can reasonably predict that its atoms are larger than those of radon, which is positioned at the far right of period 6. The periodic table is a road map to understanding the elements.
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28. 3.3 The Periodic Table Helps Us to Understand the Elements
Groups
Are vertical columns in the periodic table
Exhibit similar chemical behavior
Atomic size decreases as you move to the right
Often have traditional names associated
with them
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29. 3.3 The Periodic Table Helps Us to Understand the Elements
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30. 3.3 The Periodic Table Helps Us to Understand the Elements
Common group names
Group 1: Alkali metals
Group 2: Alkaline-earth metals
Group 16: Chalcogens
Group 17: Halogens
Group 18: Noble Gases
Transition metals correspond to groups 3 through 12
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31. Concept Check
The elements copper (Cu), silver (Ag), and gold (Au) are three of the few metals that can be found naturally in their elemental state. These three metals have found great use as coins and jewelry for a number of reasons, including their resistance to corrosion and their remarkable colors. How is the fact that these metals have similar properties reflected in the periodic table?
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32. Concept Check
Copper (number 29), silver (number 47), and gold (number 79) are all in the same group in the periodic table (group 11), which suggests that they should have similar—although not identical—properties.
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33. 3.3 The Periodic Table Helps Us to Understand the Elements
Inner transition metals
Subsets of 14 elements in period 6 and another set in period 7
Period 6 subset is called the lanthanides
Period 7 subset is called the actinides
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34. 3.3 The Periodic Table Helps Us to Understand the Elements
Typical table layout showing the
inner transition metals
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35. 3.4 Elements Can Combine to Form Compounds
Compounds form by combining elements
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36. 3.4 Elements Can Combine to Form Compounds
Compounds show different properties
from the combining atoms
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37. 3.4 Elements Can Combine to Form Compounds
Chemical formula shows the number and types of elements involved
NH3 is made up of three nitrogen atoms and one hydrogen atom
H2O is two hydrogen atoms and one
oxygen atom
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38. Concept Check
Hydrogen sulfide, H2S, is an offensively smelly compound. Rotten eggs get their characteristically unpleasant smell from the hydrogen sulfide they release. Can you conclude from this information that elemental sulfur,S8, is just as smelly? Why or why not?
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39. Concept Check
No, you cannot. In fact, the odor of elemental sulfur is negligible compared with that of hydrogen sulfide. Compounds are truly different from the elements from which they are formed. Hydrogen sulfide, H2S, is as different from elemental sulfur, S8, as water, H2O, is from elemental oxygen, O2.
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40. 3.5 There Is a System for Naming Compounds
Three basic guidelines to IUPAC naming
Element to the left is listed first followed by the one on the right with an -ide ending
When two compounds differ by number of atoms, a prefix is used to distinguish them
Atomic groups that act as a single electrically charged group have special names
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41. 3.5 There Is a System for Naming Compounds
Guideline 1
Element to the left is listed first followed by the one on the right with an -ide ending
NaCl Sodium chloride HCl Hydrogen chloride
Li2O Lithium oxide MgO Magnesium oxide
CaF2 Calcium fluoride Sr3P2Strontium phosphide
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42. 3.5 There Is a System for Naming Compounds
Guideline 2
When two compounds differ by number of atoms, a prefix is used to distinguish them
Carbon and oxygen
CO Carbon monoxide
CO2 Carbon dioxide
Nitrogen and oxygen
NO2 Nitrogen dioxide
N2O4 Dinitrogen tetroxide
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43. 3.5 There Is a System for Naming Compounds
Guideline 3
Atomic groups that act as a single electrically charged group have special names
K2CO3 Potassium carbonate
AuPO4 Gold phosphate
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44. 3.5 There Is a System for Naming Compounds
Fourth guideline
Many compounds are referred to by common names, not the systematic names
Water H2O
Ammonia NH3
Methane CH4
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45. Concept Check
What is the systematic name for Ca(CH3CO2)2? How many oxygen atoms does it have?
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46. Concept Check
The systematic name for this compound, which consists of calcium and the polyatomic acetate ion, is calcium acetate. Each acetate ion has two oxygen atoms. This compound has two acetate ions, which means it has a total of four oxygen atoms.
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47. 3.6 Most Materials Are Mixtures
A combination of two or more substances in which each retains it properties
Each substance maintains its chemical identity
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48. Concept Check
So far, you have learned about three kinds of matter: elements, compounds, and mixtures. Which box below contains only an element? Which contains only a compound? Which contains a mixture?
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49. Concept Check
Each molecule in box A contains two different types of atoms and so is representative of a compound. Each molecule in box B consists of the same atom and so is representative of an element. Box C is a mixture of the compound and the element.
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50. 3.6 Most Materials Are Mixtures
Mixtures can be separated by physical means
Solids and liquids can be separated by filtering the mixture
Liquids can be separated by their different boiling points
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51. 3.7 Matter Can Be Classified as Pure or Impure
Pure materials contain only one type of element of a single compound
Impure materials contain two or more elements or compounds
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52. 3.7 Matter Can Be Classified as Pure or Impure
Types of mixtures
Heterogeneous mixture—a mixture where the different parts can be seen
Homogenous mixture—a mixture where the differing parts cannot be seen by eye
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53. 3.7 Matter Can Be Classified as Pure or Impure
Suspension
When particles are finely mixed but not dissolved
May be solid in liquid or liquid in liquid
Suspensions will separate with a centrifuge
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54. Concept Check Impure water can be purified by
a. removing the impure water molecules.
b. removing everything that is not water.
c. breaking down the water to its simplest components.
d. adding some disinfectant, such as chlorine.
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55. Concept Check
The answer is b: Impure water can be purified by removing everything that isn’t water.
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56. 3.8 The Advent of Nanotechnology
Technology in the 10–9 meter size range
1000 times smaller than microtechnology
While no one knows the limits, some products already exist
Dental bonding agents
Mirrors that don’t fog
Stain-free clothing
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57. 3.8 The Advent of Nanotechnology
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58. 3.8 The Advent of Nanotechnology
Two main approaches to building nanoscale materials
Top-down
Making larger things smaller and smaller
Bottom-up
Building nanosized materials atom by atom
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59. 3.8 The Advent of Nanotechnology
Scanning probe microscope
Detects and characterizes surfaces of materials
Can move individual atoms
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