1. Elements and Compounds Chapter 3
Hein and Arena
Eugene Passer Chemistry Department Bronx Community College
© John Wiley and Sons, Inc
Version 2.0
12th Edition

2. Chapter Outline 3.1 Elements 3.6 Elements in Their Natural States
3.2 Distribution of Elements
Elements that Exist as Diatomic Molecules
3.3 Names of the Elements
3.4 Symbols of the Elements
3.8 Compounds
3.5 Introduction to the Periodic Table
3.9 Chemical Formulas

3. 3.1 Elements

4. An element is a fundamental or elementary substance that cannot be broken down into simpler substances by chemical means.

5. Each element has a number.
All known substances on Earth and probably the universe are formed by combinations of more than 100 elements.
Each element has a number.
Beginning with hydrogen as 1, the elements are numbered in order of increasing complexity.

6. Most substances can be decomposed into two or more simpler substances.
Water can be decomposed into hydrogen and oxygen.
Table salt can be decomposed into sodium and chlorine.
An element cannot be decomposed into a simpler substance.

7. ATOM The smallest particle of an element that can exist.
The smallest unit of an element that can enter into a chemical reaction.

8. 3.2 Distribution of Elements

9. Elements are not distributed equally by nature.
Oxygen is the most abundant element in the human body (65%).
Oxygen is the most abundant element in the crust of the earth (49.2%).
In the universe, the most abundant element is hydrogen (91%) and the second most abundant element is helium (8.75%).

10. Distribution of the common elements in nature.
3.2

11. 3.3 Names of the Elements

12. Sources of Element Names
Greek-Color
Iodine: from the Greek iodes meaning violet.
Latin-
Property
Fluorine: from the Latin fluere meaning to flow. The fluorine containing ore fluorospar is low melting.
German-
Color
Bismuth: from the German weisse mass which means white mass.
Location
Germanium: discovered in 1866 by a German chemist.
Famous-
Scientists
Einsteinium: named for Albert Einstein.

13. 3.4 Symbols of the Elements

14. A symbol stands for the element itself one atom of the element
a particular quantity of the element

15. Rules governing symbols of the elements are:
Symbols have either one or two letters.
If one letter is used it is capitalized.
C carbon
H hydrogen
If two letters are used, only the first is capitalized.
Ba barium
Ne neon

16. These symbols have carried over from the earlier names of the elements (usually Latin).
A number of symbols appear to have no connection with the element.
Most symbols start with the same letter as the element.

18. Metals, Nonmetals and Metalloids

19. Metals

20. Most elements are metals Metals are solid at room temperature.
Mercury is an exception. At room temperature it is a liquid.
Metals are good conductors of heat and electricity.
Most elements
are metals
physical
properties of metals
Metals are malleable (they can be rolled or hammered into sheets).
Metals have high luster (they are shiny).

21. Most elements are metals Metals have high densities
Metals are ductile (they can be drawn into wires).
Most metals have a high melting point.
Most elements
are metals
Metals have high densities

22. Examples of Metals
gold
lead
iron

23. Chemical Properties of Metals
Metals have little tendency to combine with each other to form compounds.
Many metals readily combine with nonmetals to form ionic compounds.
They can combine with sulfur.
chlorine.
oxygen.
In nature, minerals are formed by combinations of the more reactive metals with other elements.

24. Chemical Properties of Metals
A few of the less reactive metals such as copper, silver and gold are found in the free state.
Metals can mix with each other to form alloys.
Brass is a mixture of copper and zinc.
Bronze is a mixture of copper and tin.
Steel is a mixture of carbon and iron.

25. Nonmetals

26. Physical Properties of Nonmetals
Lack luster (they are dull)
Have relatively low melting points
Have low densities.
Poor conductors of heat and electricity
At room temperature, carbon, phosphorous, sulfur, selenium, and iodine are solids.

27. Physical State at Room Temperature
phosphorous
carbon
Solid
sulfur
selenium
iodine

28. Physical State at Room Temperature
liquid
bromine

29. gas nitrogen, oxygen fluorine, chlorine
Physical State at Room Temperature
gas
nitrogen, oxygen
fluorine, chlorine
helium, neon, argon, krypton, xenon, radon

30. Metalloids

31. Metalloids have properties that are intermediate between metals and nonmetals

32. The Metalloids
boron
silicon
germanium
arsenic
antimony
tellurium
polonium

33. Metals are found to the left of the metalloids
Nonmetals are found to the right of the metalloids.

34. 3.5 Introduction to the Periodic Table

35. N 7 The periodic table was designed by Dimitri Mendelev in 1869.
In the table each element’s symbol is placed inside of a box.
Above the symbol of the element is its atomic number. N 7

36. The elements are arranged in order of increasing atomic number.
Elements with similar chemical properties are organized in columns called families or groups . He Ne
These elements are known as the noble gases. They are nonreactive. Ar Kr Xe Rn

37. 3.6 Elements in Their Natural States

38. Most substances around us are mixtures or compounds.
THE NOBLE METALS
Gold Au
Silver Ag
Platinum Pt
Some elements are found in pure form.

39. Most substances around us are mixtures or compounds.
THE NOBLE GASES
Helium He
Neon Ne
Argon Ar
Krypton Kr
Xenon Xe
Radon Rn
Some elements are found in pure form.

40. Most substances around us are mixtures or compounds.
Air is composed mainly of nitrogen and oxygen gases.
Nitrogen and oxygen are composed of tiny two atom molecules of N2 and O2.

41. 3.7 Elements That Exist as Diatomic Molecules

42. A diatomic molecule contains exactly two atoms of the same or different elements.

44. Occurrence of Diatomic Molecules
Hydrogen H
Not found in nature. H2
Found in nature.
Nitrogen N N2

45. Hydrogen gas is found in volcanoes and it can be prepared in the laboratory.
In both cases it is diatomic hydrogen, H2.
Air is about 21% oxygen by volume.
Oxygen can also be prepared in the laboratory.
In both cases it is diatomic oxygen, O2.

46. Water has the formula H2O.
It does not contain free hydrogen, H2 or free oxygen, O2.
The H2 part of H2O means that 2 atoms of hydrogen are combined with one atom of oxygen in the water molecule. H2 O2
H2O

47. 3.8 Compounds

48. A compound is a distinct substance that contains two or more elements combined in a definite proportion by weight.

49. Compounds can be decomposed chemically into simpler substances–that is, into simpler compounds or elements.
Elements cannot be decomposed into simpler substances.
Atoms of the elements that constitute a compound are always present in simple whole number ratios. They are never present as fractional parts.

50. There are two types of compounds: molecular and ionic.

51. Molecules

52. A molecule is the smallest uncharged individual unit of a compound formed by the union of two or more atoms.

53. A water molecule consists of two hydrogen atoms and one oxygen atom.
If it is subdivided the water molecule will be destroyed and hydrogen and oxygen will be formed.
3.5

54. Ionic Compounds

55. An ion is a positively or negatively charged atom or group of atoms.

56. A cation is a positively charged ion.
3.5

57. An anion is a negatively charged ion.
3.5

58. Ionic compounds are held together by attractive forces between positively and negatively charged ions.

59. Sodium Chloride
Sodium chloride is a colorless crystalline ionic substance.
It is 39.3% sodium and 60.7% chlorine by mass.
The solid does not conduct electricity.
Passing an electric current through the molten salt produces solid sodium and gaseous chlorine.

60. Sodium Chloride
The ultimate particles of sodium chloride are positively charged sodium ions and negatively charged chloride ions.
3.5

61. Sodium Chloride
The crystalline structure of sodium chloride is held together by the attractive forces between the positive sodium ions and the negative chloride ions.

62. Ionic Compound Formulas

63. The actual chemical formulas of ionic compounds express the smallest whole number ratio that exists between the cations and the anions.
Sodium chloride and other ionic compounds consist of large aggregates of cations and anions.

64. The formula NaCl does not mean that a molecule of NaCl exists.
The formula NaCl means that the ratio of sodium to chlorine in a sodium chloride crystal is one to one.

65. The ratio of Na+ to Cl- is 1:1

66. Compounds can be classified as molecular or ionic
Compounds can be classified as molecular or ionic. Ionic compounds are held together by attractive forces between their positive and negative charges. Molecular compounds are held together by covalent bonds.
3.3

67. 3.9 Chemical Formulas

68. calcium CaCl2 chloride chemical formulas
Serve as abbreviations of the names of compounds.
CaCl2
calcium
chloride

69. calcium CaCl2 chlorine chemical formulas
Tell which elements the compound is composed of and how many atoms of each element are present in a formula unit.
CaCl2
calcium
chlorine

70. Ca calcium CaCl2 Cl chlorine chemical formulas
Show the symbols of the atoms of the elements present in a compound.
CaCl2
Ca calcium
Cl chlorine

71. CaCl2 chemical formulas
Show the ratio of the atoms of the elements present in a compound.
CaCl2

72. Rules for Writing Chemical Formulas

73. When a formula contains one atom of an element, the symbol of that element represents the one atom. The number one (1) is not used as a subscript.

74. NaCl indicates the element sodium (one atom) indicates
the element chlorine
(one atom)

75. When the formula contains more than one atom of an element, the number of atoms is indicated by a subscript written to the right of the symbol of that atom.

76. H3PO4 indicates the element oxygen (O) indicates indicates the element
hydrogen (H)
indicates
the element
phosphorous (P)
indicates
4 O atoms
indicates
3 H atoms

77. When the formula contains more than one of a group of atoms that occurs as a unit, parentheses are placed around the group, and the number of units of the group is indicated by a subscript placed to the right of the parentheses.

78. Ba3(PO4)2 indicates the element barium indicates three Ba atoms
indicates the phosphate group
composed of one phosphorous
atom and four oxygen atoms
indicates three Ba atoms

79. Formulas written as H2O, H2SO4, Ca(NO3)2 and C12H22O11 show only the number and kind of each atom contained in the compound; they do not show the arrangements of the atoms in the compound or how they are chemically bonded to each other.

80. H2O

81. The End