Chapter 6. 6.1  In a self-service store, the products are grouped according to similar characteristics. With a logical classification system, finding.

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Chapter 6

6.1  In a self-service store, the products are grouped according to similar characteristics. With a logical classification system, finding and comparing products is easy. You will learn how elements are arranged in the periodic table and what that arrangement reveals about the elements.

 Searching For an Organizing Principle ◦ How did chemists begin to organize the known elements?  Chemists used the properties of elements to sort them into groups (vertical columns). 6.1

 Chlorine, bromine, and iodine have very similar chemical properties. 6.1

 Mendeleev’s Periodic Table ◦ How did Mendeleev organize his periodic table?  Mendeleev organized elements into groups based on a set of repeating properties and according to increasing atomic mass.  He used the periodic table to predict the properties of undiscovered elements. 6.1

 An Early Version of Mendeleev’s Periodic Table 6.1

 The Periodic Law ◦ How is the modern periodic table organized?  In the modern periodic table, elements are arranged in order of increasing atomic number. 6.1

 The periodic law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.  The properties of the elements within a period (row) change as you move across a period from left to right.  This same pattern of properties then repeats across the next period. 6.1

 Metals, Nonmetals, and Metalloids ◦ What are three broad classes of elements?  Three classes of elements are metals, nonmetals, and metalloids. 6.1

 Metals, Metalloids, and Nonmetals in the Periodic Table 6.1

 Metals, Metalloids, and Nonmetals in the Periodic Table 6.1

◦ Metals  Metals are good conductors of heat and electric current.  80% of elements are metals.  All metals are solids at room temperature except mercury, which is a liquid.  Metals have a high luster, are ductile, and are malleable. 6.1

 Uses of Iron, Copper, and Aluminum 6.1

 Uses of Iron, Copper, and Aluminum 6.1

 Uses of Iron, Copper, and Aluminum 6.1

 Metals, Metalloids, and Nonmetals in the Periodic Table 6.1

◦ Nonmetals  In general, nonmetals are poor conductors of heat and electric current.  Most nonmetals are gases at room temperature.  A few nonmetals are solids, such as sulfur and phosphorus.  One nonmetal, bromine, is a dark-red liquid. 6.1

 Metals, Metalloids, and Nonmetals in the Periodic Table 6.1

◦ Metalloids  A metalloid generally has properties that are similar to those of metals and nonmetals.  The behavior of a metalloid can be controlled by changing conditions.  Metalloids are also known as semi-metals. 6.1

 If a small amount of boron is mixed with silicon, the mixture is a good conductor of electric current. Silicon can be cut into wafers, and used to make computer chips. 6.1

◦ Across a period, the properties of elements become less metallic and more nonmetallic. ◦ Down a group (column), the properties of elements become more metallic and less nonmetallic. Where is the most metallic element?

6.2  A coin may contain much information in a small space—its value, the year it was minted, and its country of origin. Each square in a periodic table also contains information. You will learn what types of information are usually listed in a periodic table.

6.2  Squares in the Periodic Table ◦ What type of information can be displayed in a periodic table?  The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms.

http://www.privatehand.com/flash/elements.html

 Some element families have names: ◦ The Group 1 elements are called alkali metals. ◦ The Group 2 elements are called alkaline earth metals. ◦ The nonmetals of Group 17 are called halogens. ◦ The nonmetal gases of group 18 are called noble gases. 6.2

 Electron Configurations in Groups ◦ How can elements be classified based on their electron configurations?  Elements can be sorted into groups based on their electron configurations.  Elements in the same family have the same outer electron configuration = valence electrons. 6.2

◦ The Noble Gases  The noble gases are the elements in Group 18 of the periodic table; all noble gases have a full outer electron energy level. 6.2 Helium (He)2 Neon (Ne)2-8 Argon (Ar)2-8-8 Krypton (Kr)2-8-18-8

◦ The alkali metals.  In atoms of the Group 1 elements below, there is only one electron in the highest occupied energy level; one valence electron. 6.2 Lithium (Li)2-1 Sodium (Na)2-8-1 Potassium (K)2-8-8-1

◦ The carbon family  In atoms of the Group 14 elements below, there are four valence electrons. 6.2 Carbon (C)2-4 Silicon (Si)2-8-4 Germanium (Ge)2-8-18-4

 Transition Elements  There are two types of transition elements—transition metals and inner transition metals. They are classified based on their electron configurations. 6.2

 In atoms of a transition metal, the d sublevel is filling with electrons.  In atoms of an inner transition metal, the f sublevel is filling with electrons. 6.2

◦ Blocks of Elements 6.2

 The Elements: Forged in Stars - YouTube The Elements: Forged in Stars - YouTube

 In the Earth’s Crust: ◦ Oxygen ◦ Silicon ◦ Aluminum ◦ Iron ◦ Calcium ◦ Sodium ◦ Potassium ◦ Magnesium ◦ Titanium ◦ Hydrogen

 Dissolved in the Oceans: ◦ Chlorine ◦ Sodium ◦ Magnesium ◦ Sulfur ◦ Calcium ◦ Potassium ◦ Bromine ◦ Carbon ◦ Strontium ◦ Boron

 In the Atmosphere: ◦ Nitrogen ◦ Oxygen ◦ Argon ◦ Neon ◦ Helium ◦ Krypton ◦ Hydrogen ◦ Xenon ◦ Radon

 In the Sun: ◦ Hydrogen ◦ Helium ◦ Oxygen ◦ Carbon ◦ Nitrogen ◦ Silicon ◦ Magnesium ◦ Neon ◦ Iron ◦ Sulfur

 In your body: ◦ Oxygen ◦ Carbon ◦ Hydrogen ◦ Nitrogen ◦ Calcium ◦ Phosphorus ◦ Sulfur ◦ Potassium ◦ Sodium ◦ Chlorine

 Soft, silver-grey metals.  Low melting and boiling points.  One valence electron.  Most reactive: not found uncombined in nature. ◦ Obtained in the pure form by electrolysis of their fused salts.  Potassium Video - The Periodic Table of Videos - University of Nottingham Potassium Video - The Periodic Table of Videos - University of Nottingham

 Relatively soft, but harder than alkali metals.  Two valence electrons.  Although not as reactive as alkali metals, still very reactive and not found in nature in the elemental state. ◦ Obtained in the pure form through electrolysis of their fused salts.  Densities, melting and boiling points are higher than respective alkali metals.  Radium Video - The Periodic Table of Videos - University of Nottingham Radium Video - The Periodic Table of Videos - University of Nottingham

 Most are ductile, malleable and good conductors of heat and electricity.  Compounds of transition metals tend to have color.  One or two valence electrons.  Obtained from mineral deposits (ores) in the earth’s crust (smelting).  Precious metals are used for currency among other things.  Darmstadtium Video - The Periodic Table of Videos - University of Nottingham Darmstadtium Video - The Periodic Table of Videos - University of Nottingham

 Nonmetals.  Very reactive; not found in nature uncombined. ◦ Obtained from the electrolysis of their fused salts.  Seven valence electrons.  Commercial applications include antibacterial properties.  Chlorine Video - The Periodic Table of Videos - University of Nottingham Chlorine Video - The Periodic Table of Videos - University of Nottingham

 Full outer electron level.  Non-reactive (inert) gases. ◦ Can be forced to combine with fluorine.  Commercial applications include colored signs lit up as discharge tubes.  Incandescent light bulbs are filled with argon.  Radon Video - The Periodic Table of Videos - University of Nottingham Radon Video - The Periodic Table of Videos - University of Nottingham

 Sodium chloride (table salt) produced the geometric pattern in the photograph. Such a pattern can be used to calculate the position of nuclei in a solid. You will learn how properties such as atomic size are related to the location of elements in the periodic table. 6.3

 Trends in Atomic Size ◦ What are the trends among the elements for atomic size?  The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined. 6.3

◦ Group and Periodic Trends in Atomic Size  In general, atomic size increases from top to bottom within a group and decreases from left to right across a period.  Down a group, atomic size increases due to additional energy levels.  Across a period atomic size decreases due to increasing nuclear charge. 6.3

 Some compounds are composed of particles called ions.  An ion is an atom or group of atoms that has a positive or negative charge.  A cation is an ion with a positive charge.  An anion is an ion with a negative charge. 6.3

 Ions ◦ How do ions form? 6.3

 Positive ions form when an atom loses electron(s). 6.3

 Negative ions form when an atom gains electron(s). 6.3

 Trends in Ionization Energy ◦ What are the trends among the elements for first ionization energy, ionic size, and electronegativity?  The energy required to remove an electron from an atom is called ionization energy.  The energy required to remove the first electron from an atom is called the first ionization energy.  The energy required to remove a second electron is called the second ionization energy. 6.3

◦ Group and Periodic Trends in Ionization Energy  First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.  Down a group increasing levels of electrons shield the effect of the nucleus therefore reducing energy needed to remove an outer electron.  Across a period there in no increase in energy levels, and increasing nuclear charge makes it more difficult to remove an outer electron. 6.3

 Trends in Ionic Size ◦ During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form.  Cations are always smaller than the atoms from which they form.  Anions are always larger than the atoms from which they form. 6.3

 Relative Sizes of Some Atoms and Ions 6.3

 Trends in Electronegativity ◦ Electronegativity is the ability of an atom to attract electrons to itself when it is in involved in a bond.  In general, electronegativity values decrease from top to bottom within a group, and increase from left to right across a period.  Electronegativity decreases down a group because of increasing atomic size and the shielding effect of inner level electrons.  Electronegativity increases across a period because of decreasing atomic size and increasing nuclear charge. 6.3

 Summary of Trends ◦ What is the underlying cause of periodic trends?  Periodic trends can be explained by variations in atomic structure, nuclear charge, and shielding effect. 6.3

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