Chapter 5 The Periodic Law Patterns of the Periodic Table

Section 1 / History of the Periodic Table

History / Atomic masses standardized in 1860 / Mendeleev organized all known elements according to atomic mass and chemical and physical properties / Atomic masses standardized in 1860 / Mendeleev organized all known elements according to atomic mass and chemical and physical properties

History / Medeleev noticed a trend in physical/chemical properties  Trends were “ periodic ” which means there is a repeating pattern / Medeleev noticed a trend in physical/chemical properties  Trends were “ periodic ” which means there is a repeating pattern

History / Mendeleev left several empty spaces / Predicted that some elements were not discovered yet. / Scandium, Gallium, and Germanium / Mendeleev left several empty spaces / Predicted that some elements were not discovered yet. / Scandium, Gallium, and Germanium

History / Mendeleev arranged elements by atomic mass / In 1911, Henry Moseley arranged elements by nuclear charge (proton or atomic number) / Mendeleev arranged elements by atomic mass / In 1911, Henry Moseley arranged elements by nuclear charge (proton or atomic number)

History / Periodic Law: The physical and chemical properties of the elements are periodic functions of their atomic numbers. / patterns repeat according to atomic number / Periodic Law: The physical and chemical properties of the elements are periodic functions of their atomic numbers. / patterns repeat according to atomic number

Modern Periodic Table  About 40 more elements have been discovered or created since Mendeleev ’ s time

Noble Gases / Discovered in 1894 by Lord Rayleigh and Sir William Ramsay (Argon) / Very difficult to discover since they are not reactive (inert) / Helium was discovered to exist on the Sun in 1865, but thought not to exist on Earth. (discovered in 1895) / Discovered in 1894 by Lord Rayleigh and Sir William Ramsay (Argon) / Very difficult to discover since they are not reactive (inert) / Helium was discovered to exist on the Sun in 1865, but thought not to exist on Earth. (discovered in 1895)

Noble Gases / Ramsay made a new group for Helium and Argon / 1898 Ramsay discovered Krypton and Xenon / Radon discovered two years later by Dorn / Ramsay made a new group for Helium and Argon / 1898 Ramsay discovered Krypton and Xenon / Radon discovered two years later by Dorn

S block elements Group 1 and 2 / Highly reactive elements / Usually found bonded to other elements in nature (compounds) / Highly reactive elements / Usually found bonded to other elements in nature (compounds)

Group 1 elements / Known as the alkali metals / All have an ns 1 outer electron configuration / Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium, Francium / Known as the alkali metals / All have an ns 1 outer electron configuration / Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium, Francium

Group 2 elements / Known as the alkaline earth metals / ns 2 valence electron configuration / Less reactive than Group 1 elements / Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium / Known as the alkaline earth metals / ns 2 valence electron configuration / Less reactive than Group 1 elements / Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium

Hydrogen and Helium / Exceptions  Hydrogen ’ s properties do not resemble the alkali metals (behaves like a metal under extremely high pressures)  Helium ’ s E.C. is 1s 2, but it doesn ’ t act like a Group 2 (acts like noble gas) / Exceptions  Hydrogen ’ s properties do not resemble the alkali metals (behaves like a metal under extremely high pressures)  Helium ’ s E.C. is 1s 2, but it doesn ’ t act like a Group 2 (acts like noble gas)

The d-Block Elements Groups 3-12 / Known as transition metals / Less reactive than alkali metals/alkaline earth metals / Some exist as free elements in nature / Palladium platinum and gold / Known as transition metals / Less reactive than alkali metals/alkaline earth metals / Some exist as free elements in nature / Palladium platinum and gold

P-Block Elements Groups / Properties vary greatly / Includes metals, metalloids, and nonmetals / Valence electrons are equal to group number minus 10 / Properties vary greatly / Includes metals, metalloids, and nonmetals / Valence electrons are equal to group number minus 10

Halogens / Group 17 elements / Fluorine, Chlorine, Bromine, Iodine, and Astatine / valence configuration is ns 2 np 5 / Most reactive non metals / React vigorously with metals / Group 17 elements / Fluorine, Chlorine, Bromine, Iodine, and Astatine / valence configuration is ns 2 np 5 / Most reactive non metals / React vigorously with metals

F-block Elements Lanthanides and Actinides / Shiny metals / Most are radioactive / Elements above atomic number 92 (Uranium) are man made / Shiny metals / Most are radioactive / Elements above atomic number 92 (Uranium) are man made

Periodic Trends

Periodic Law / When elements are arranged in order of increasing atomic #, elements with similar properties appear at regular intervals.

Chemical Reactivity / Families / Similar valence e - within a group result in similar chemical properties / Families / Similar valence e - within a group result in similar chemical properties

Chemical Reactivity / Alkali Metals / Alkaline Earth Metals / Transition Metals / Halogens / Noble Gases / Alkali Metals / Alkaline Earth Metals / Transition Metals / Halogens / Noble Gases

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/ Atomic Radius Atomic Radius Li Ar Ne K Na

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/ Atomic Radius / Increases to the LEFT and DOWN D. Atomic Radius

/ Why larger going down? / Higher energy levels have larger orbitals / Shielding - core e - block the attraction between the nucleus and the valence e - / Why smaller to the right? / Increased nuclear charge without additional shielding pulls e - in tighter / Why larger going down? / Higher energy levels have larger orbitals / Shielding - core e - block the attraction between the nucleus and the valence e - / Why smaller to the right? / Increased nuclear charge without additional shielding pulls e - in tighter D. Atomic Radius

/ First Ionization Energy E. Ionization Energy K Na Li Ar Ne He

/ First Ionization Energy / Increases UP and to the RIGHT E. Ionization Energy

/ Why opposite of atomic radius? / In small atoms, e - are close to the nucleus where the attraction is stronger / Why opposite of atomic radius? / In small atoms, e - are close to the nucleus where the attraction is stronger E. Ionization Energy

/ Successive Ionization Energies / Mg1st I.E.736 kJ 2nd I.E.1,445 kJ Core e - 3rd I.E.7,730 kJ / Large jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy

/ Al1st I.E.577 kJ 2nd I.E.1,815 kJ 3rd I.E.2,740 kJ Core e - 4th I.E. 11,600 kJ / Successive Ionization Energies / Large jump in I.E. occurs when a CORE e - is removed. E. Ionization Energy

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/ Which atom has the larger radius? / BeorBa / CaorBr Ba Ca Examples

/ Which atom has the higher 1st I.E.? / NorBi / BaorNe N Ne Examples

/ Which particle has the larger radius? / SorS 2- / AlorAl 3+ S 2- Al Examples

Electron Affinity / Neutral atoms can also acquire electrons. / The energy change that occurs when an electron is acquired by a neutral atom is call the atoms electron affinity. / Neutral atoms can also acquire electrons. / The energy change that occurs when an electron is acquired by a neutral atom is call the atoms electron affinity.

Electron affinity / Trend EA increases left to right / EA decreases going down / Trend EA increases left to right / EA decreases going down

Electronegativity / Electronegativity is a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound.

Electronegativity / Tend to increase across each period (left to right) / Tend to decrease going down / Tend to increase across each period (left to right) / Tend to decrease going down