Development of the Periodic Table
John Newlands - Law of Octaves 1864 When arranged in order of atomic mass, every eighth element had similar properties.
Dimitri Mendeleev / Lothar Meyer 1869 organized elements arranged according to atomic mass. Mendeleev showed how useful the table could be in predicting the existence and properties of yet unknown elements
Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Modern Periodic Table - Henry Mosley 20th Century Organized according to atomic number.
an elements position on the periodic table gives indications of its various physical and chemical properties
Metals, Nonmetals and Metalloids
Metals Metalloids Nonmetals In chemical reactions metals tend to lose electrons to nonmetals
Properties of Metal, Nonmetals, and Metalloids 2012 Pearson Education, Inc. Periodic Properties of the Elements
Metals versus Nonmetals Metals tend to form cations. Nonmetals tend to form anions. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Metals Metals tend to be lustrous, malleable, ductile, and good conductors of heat and electricity. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Metals Compounds formed between metals and nonmetals tend to be ionic. Metal oxides tend to be basic. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Nonmetals Nonmetals are dull, brittle substances that are poor conductors of heat and electricity. They tend to gain electrons in reactions with metals to acquire a noble-gas configuration. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Nonmetals Substances containing only nonmetals are molecular compounds. Most nonmetal oxides are acidic. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Metalloids Metalloids have some characteristics of metals and some of nonmetals. For instance, silicon looks shiny, but is brittle and a fairly poor conductor. 2012 Pearson Education, Inc. Periodic Properties of the Elements
metals good conductors of heat and electricity malleable nonmetals poor conductors brittle ductile lustrous tend to lose electrons in chemical reactions tend to gain electrons in chemical reactions
Specific Groups
Main groups group numbers identified by suffix A
Main group metals Alkali metals Alkaline earth metals
Nonmetals Halogens Noble gases
Actinides transition metals Lanthanides
Periodic Classification of the Elements
Valence Electrons The outer electrons of an atom, which are those involved in chemical bonding, are often called the valence electrons. Elements in the same group of the periodic table have analogous valence-electron figurations.
Group 8A noble gases 1 2 3 4 5 6 He Ne Ar Kr Xe Rn 1s 2 [He]2s 2 2p 6 [Ne]3s 2 3p 6 [Ar]3d 10 4s 2 4p 6 [Kr]4d 10 5s 2 5p 6 [Xe]5d 10 4f 14 6s 2 6p 6
Group 1A alkali metals 1 2 3 4 5 6 7 H Li Na K Rb Cs Fr 1s 1 [He]2s 1 [Ne]3s 1 [Ar]4s 1 [Kr]5s 1 [Xe]6s 1 [Rn]7s 1
Group 2A Alkaline earth metals 2 3 4 5 6 7 Be Mg Ca Sr Ba Ra [He]2s 2 [Ne]3s 2 [Ar]4s 2 [Kr]5s 2 [Xe]6s 2 [Rn]7s 2
Group 7A halogens 2 3 4 5 6 F Cl Br I At 2s 2 2p 5 3s 2 3p 5 4s 2 4p 5 5s 2 5p 5 6s 2 6p 5
Ions
Ions When electrons are removed from or added to a neutral atom or molecule, a charged particle called an ion is formed.
Positively charged ions are called cations Negatively charged ions are called anions
Ions positively charged: cations most common type is metal cation Na +, Ca 2+, Al 3+, Fe 2+, Fe 3+ negatively charged: anions most common type is nonmetal anion Cl, O 2
the chemical behavior of an atom depends on how hard an atom holds on to its electrons
Effective Nuclear Charge In a many-electron atom, electrons are both attracted to the nucleus and repelled by other electrons. The nuclear charge that an electron experiences depends on both factors. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Metals Nonmetals In chemical reactions metals tend to lose electrons to nonmetals
Atoms vs Ions Na: 11 protons; 11 electrons Cl: 17 protons; 17 electrons
Electron Configurations of Cations and Anions Element Atom Ion Sodium Na [Ne]3s 1 Magnesium Mg [Ne]3s 2 Aluminum Al [Ne]3s 2 3p 1 Na + [Ne] Mg 2+ [Ne] Al 3+ [Ne] Isoelectronic species have the same number of electrons.
Electron Configurations of Cations and Anions Element Atom Ion Hydrogen H 1s 1 H Fluorine F 1s 2 2s 2 2p 5 F Oxygen O 1s 2 2s 2 2p 4 O 2 Nitrogen N 1s 2 2s 2 2p 3 N 3 1s 2 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 Isoelectronic species have the same number of electrons.
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Alkali Metals Alkali metals are soft, metallic solids. The name comes from the Arabic word for ashes. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Alkali Metals They are found only in compounds in nature, not in their elemental forms. They have low densities and melting points. They also have low ionization energies. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Alkali Metals Their reactions with water are famously exothermic. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Alkali Metals Alkali metals (except Li) react with oxygen to form peroxides. K, Rb, and Cs also form superoxides: K + O 2 KO 2 They produce bright colors when placed in a flame. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Alkaline Earth Metals Alkaline earth metals have higher densities and melting points than alkali metals. Their ionization energies are low, but not as low as those of alkali metals. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Alkaline Earth Metals Beryllium does not react with water, and magnesium reacts only with steam, but the other alkaline earth metals react readily with water. Reactivity tends to increase as you go down the group. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Group 6A Oxygen, sulfur, and selenium are nonmetals. Tellurium is a metalloid. The radioactive polonium is a metal. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Sulfur Sulfur is a weaker oxidizer than oxygen. The most stable allotrope is S 8, a ringed molecule. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Group VIIA: Halogens The halogens are prototypical nonmetals. The name comes from the Greek words halos and gennao: salt formers. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Group VIIA: Halogens They have large, negative electron affinities. Therefore, they tend to oxidize other elements easily. They react directly with metals to form metal halides. Chlorine is added to water supplies to serve as a disinfectant. 2012 Pearson Education, Inc. Periodic Properties of the Elements
Group VIIIA: Noble Gases The noble gases have astronomical ionization energies. Their electron affinities are positive. Therefore, they are relatively unreactive. They are found as monatomic gases. 2012 Pearson Education, Inc. Periodic Properties of the Elements