High School Physical Science
Week 7
The Periodic Table
Vocabulary
•valence electron, energy level, period, group,and family.
•Metals, non-metals, and metalloids
History and Development
•Mendeleev developed the first periodic tableby listing the elements in order of increasingatomic mass. He used his table to predict thatelements with certain properties would bediscovered later.
•Properties of elements repeat in a regular, orperiodic, pattern.
•Moseley rearranged the elements in order ofincreasing atomic number.
Arrangement
•The periodic law states that the repeatingchemical and physical properties of elementsrelate to and depend on elements’ atomicnumbers.
•Elements in the periodic table are classified asmetals, nonmetals, and metalloids.
Arrangement
•Each element has a chemical symbol.
•A horizontal row of elements is called aperiod.
•Physical and chemical properties of elementschange across each period.
•A vertical column of elements is called a groupor family.
•Elements in a group usually have similarproperties.
Families/Groups
•Alkali metals (Group 1) are the most reactivemetals. Atoms of the alkali metals have oneelectron in their outer level.
•Alkaline-earth metals (Group 2) are lessreactive than the alkali metals are. Atoms ofthe alkaline-earth metals have two electronsin their outer level.
Families/Groups
•Transition metals (Groups 3–12) include mostof the well-known metals and the lanthanidesand actinides.
•Groups 13–16 contain the metalloids andsome metals and nonmetals.
Families/Groups
•Halogens (Group 17) are very reactivenonmetals. Atoms of the halogens have sevenelectrons in their outer level.
•Noble gases (Group 18) are unreactivenonmetals. Atoms of the noble gases have afull set of electrons in their outer level.
•Hydrogen is set off by itself. Its properties donot match the properties of any one group.