Notes

Outline

The Periodic Table Mr. Hayhurst Lancaster High School Physical Science

Arranging the Elements -system of classifying or logically grouping all of the known elements -brings order to thousands of seemingly unrelated facts -helped chemists predict the existence of elements that weren’t discovered yet -groups elements according to their chemical and physical properties

Developed by a Russian chemist named Dmitri Mendeleev (duh-MEE-tree mehn-duh-LAY-uhf) Mendeleev used the following categories to organize his table: chemical properties physical properties atomic mass density color melting point valence

"When arranged in order of..." When arranged in order of atomic mass from Lithium through Fluorine the pattern of valences is 1 2 3 4 3 2 1 in each row of seven. This is true for all of the elements in the column. Therefore the name periodic came about: the elements formed a definite repeating pattern, very similar to a calendar.

Because of this pattern he could make predictions about elements which had not yet been discovered.

The Periodic Law The periodic law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers.

Design of the Periodic Table -organizes information in a logical, usable, and meaningful way -allows prediction of physical and chemical properties of an element by position -can predict what other elements will react with a particular element -arranged in columns and rows because of similar characteristics

Columns in the Periodic Table -vertical classification or groupings -often referred to as families or groups -each column is numbered 1-18 or Ia through VIII -elements within the same family have similar properties

Rows in the Periodic Table -horizontal classification or groupings -each row is called a period -elements in a period are not alike in properties, properties change greatly across a given row -the first element in a period is a very active metal -the last element in most periods is a noble gas -only seven periods

Element Key Important information about an element is given in each square of the periodic table: its atomic number chemical symbol element name atomic mass

Three main categories of elements on the Periodic Table metals nonmetals metalloids

Physical Properties of Metals -luster (shininess) -conductivity of heat and electricity -high density -high melting point -ductility (they are ductile) -malleability (they are malleable)

Chemical Properties of Metals -not easily observed -1, 2, 3, or 4 electrons in its outermost energy level -tend to lose their electrons in a reaction -easily susceptible to corrosion Corrosion is the gradual wearing away of metal due to a chemical reaction in which the metal element is changed into a metallic compound.

Nonmetals -located to the right of the zigzag line -fewer nonmetals than metals

Physical properties of nonmetals -have no luster or are dull in appearance -do not conduct heat and electricity well -do not possess the properties of ductility or malleability -lower density and lower melting point -nonmetals can be very different, range from a gas to liquid to a solid -can also be colored extremely different

Chemical properties of nonmetals -5, 6, 7, or 8 electrons in the outermost energy level -atoms with 5, 6, or 7 valence electrons gain 3, 2, or 1 electron when they combine chemically -elements with 8 electrons in their outermost shell tend to be non-reactive -react mainly with metals

Metalloids -means metal-like -include; Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, Polonium and Astatine -have some of the properties of metals and some of the properties of non metals -are solids that are shiny or dull -conduct heat and electricity but not as well as metals -are ductile and malleable

Chemical Families -Vertical classification of elements or columns -Elements within the same family of the periodic table have similar properties because they have the same number of valence electrons

"Ten major families:" Ten major families: 1. alkali metals 2. alkaline earth metals 3. transition elements 4. boron family 5. carbon family 6. nitrogen family 7. oxygen family 8. halogen family 9. noble gases 10. rare earth metals

Alkali Metals -one electron in their outermost shell or one valence electron -soft, silver-white, shiny metals -bond readily with other substances -never found uncombined in nature -samples must be stored in oil to keep them from combining with water or oxygen -most reactive metals

Alkaline Earth Metals -two valence electrons -lose 2 electrons when combined with other substances -never found uncombined in nature -not quite as reactive as the alkali metals -often mixed with other metals, such as aluminum, to form alloys of strong yet light in weight metals

Transition Metals -located between alkaline earth metals family and the boron family -have similar properties to each other but different than other families -most things we think of as metal are part of the transition metals

Boron Family Boron hard and brittle never found uncombined in nature found in borax used to make heat resistant glass

Boron Family Aluminum most abundant metal, 3rd most abundant metal in earth’s crust found in a mineral called bauxite extremely important metal for industry, light, strong and slow to corrode

Carbon Family -have 4 valance electrons -can either gain 4 electrons or lose 4 electrons -includes; Carbon (nonmetal), Silicon (metalloid), Germanium (metalloid), Tin (metal), and lead (metal)

Nitrogen Family -have 5 valence electrons -tend to gain three electrons

Oxygen Family -have 6 valence electrons -tend to gain 2 electrons

Halogen Family -have 7 valence electrons -most active nonmetals -never found free in nature -react with the alkali metals quite easily -when halogens react with metals they form compounds called salts -Fluorine is the most active halogen

The Noble Gases -normally non-reactive -also called inert -all elements in this family are gases -outermost electron shell is full -found in small amounts in the earth’s atmosphere (less than 1%)

Rare-Earth Elements Located in the two rows at the bottom of the Periodic Table -first row called the lanthanide series -used to make glass alloys -the second row called the actinide series -all actinides are radioactive

The Periodic Table The End Copyright © 2000, Pat Hayhurst Lancaster High School