CHAPTER 3 Electronic Structure and the Periodic Law

CHAPTER 3 Electronic Structure and the Periodic Law

. Metals, Nonmetals, and Metalloids Metals, Metalloids, and Nonmetals in the Periodic Table

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

Properties of Metals Metals are good conductors of heat and electricity Metals are malleable Metals are ductile Metals have high tensile strength Metals have luster

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

Nonmetals Nonmetals are poor conductors of heat and electricity Nonmetals tend to be brittle Many nonmetals are gases at room temperature Carbon, the graphite in pencil lead is a great example of a nonmetallic element.

Examples of Nonmetals Sulfur, S, was once known as brimstone Microspheres of phosphorus, P, a reactive nonmetal Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

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

Properties of Metalloids They have properties of both metals and nonmetals. Metalloids are more brittle than metals, less brittle than most nonmetallic solids Metalloids are semiconductors of electricity Some metalloids possess metallic luster Polonium is NOT a metalloid

Silicon, Si A Metalloid Other metalloids include: Boron, B Germanium, Ge Arsenic, As Antimony, Sb Tellurium, Te Silicon has metallic luster Silicon is brittle like a nonmetal Silicon is a semiconductor of electricity

3.1 PERIODIC LAW This is a statement about the behavior of the elements when they are arranged in a specific order. PERIODIC LAW: Elements with similar chemical properties occur at regular (periodic) intervals when the elements are arranged in order of increasing atomic numbers.

PERIODIC TABLE A periodic table is a tabular arrangement of the elements based on the periodic law. In a modern periodic table, elements with similar chemical properties are found in vertical columns called groups or families. 18 groups/families 7 periods

PERIODIC TABLE GROUP OR FAMILY A group or family is a vertical column of elements that have similar chemical properties. Each family has a specific name to differentiate it from the other families in the periodic table. Elements in each family react differently with other elements. The U.S. system uses a Roman numeral and a letter (either A or B) at the top of the column. The IUPAC (but not universally-used) system uses only a number from 1 to 18.

Alkali Metals All alkali metals have 1 valence electron Alkali metals are NEVER found pure in nature; they are too reactive Reactivity of these elements increases down the group Hydrogen is not a member, it is a non-metal Potassium, K reacts with water and must be stored in kerosene

Alkaline Earth Metals All alkaline earth metals have 2 valence electrons Alkaline earth metals are less reactive than alkali metals Alkaline earth metals are not found pure in nature; they are too reactive The word alkaline means basic common bases include salts of the metals Ca(OH) 2 Mg(OH) 2

Halogens Halogens all have 7 valence electrons Halogens are never found pure in nature; they are too reactive Halogens in their pure form are diatomic molecules (F 2, Cl 2, Br 2, and I 2 ) All are non-metals Very reactive are often bonded with elements from Group 1 Chlorine is a yellow-green poisonous gas

Noble Gases Noble gases are ONLY found pure in nature they are chemically unreactive Exist as gases Non-metals 8 electrons in the outer shell = Full Helium (He) has only 2 electrons in the outer shell = Full Colorless, odorless and unreactive; they were among the last of the natural elements to be discovered

BORON FAMILY Group 3 3 electrons in the outer shell Most are metals Boron is a metalloid

CARBON FAMILY Group 4 4 electrons in the outer shell Contains metals, metalloids, and a non-metal Carbon (C)

NITROGEN FAMILY Group 5 5 electrons in the outer shell Can share electrons to form compounds Contains metals, metalloids, and non-metals

OXYGEN FAMILY Group 6 6 electrons in the outer shell Contains metals, metalloids, and non-metals Reactive

TRANSITION METALS Groups in the middle Good conductors of heat and electricity. Some are used for jewelry. The transition metals are able to put up to 32 electrons in their second to last shell. Can bond with many elements in a variety of shapes.

Rare Earth Metals Some are Radioactive The rare earths are silver, silverywhite, or gray metals. Conduct electricity

PERIODIC TABLE PERIOD A period is a horizontal row of elements arranged according to increasing atomic numbers. Periods are numbered from top to bottom of the periodic table.

MODERN PERIODIC TABLE Elements 58-71 and 90-103 are not placed in their correct periods, but are located below the main table.

GROUP & PERIOD IDENTIFICATION ELEMENTS AND THE PERIODIC TABLE Each element belongs to a group and period of the periodic table. EXAMPLES OF GROUP AND PERIOD LOCATION FOR ELEMENTS Calcium, Ca, element 20: group II A (2), period 4 Silver, Ag, element 47: group I B (11), period 5 Sulfur, S, element 16: group VI A (16), period 3

3.2 BOHR THEORY Bohr proposed that the electron in a hydrogen atom moved in any one of a series of circular orbits around the nucleus. The electron could change orbits only by absorbing or releasing energy. This model was replaced by a revised model of atomic structure in 1926.