PERIODIC TABLE Dmitri Mendeleev Russian chemist school teacher

PERIODIC TABLE

Dmitri Mendeleev Russian chemist / school teacher Youngest of 17 children Noticed trends in the known elements PERIODIC LAW: When elements are arranged in order of increasing relative mass, certain sets of properties recur periodically

Dmitri Mendeleev His initial organization of the elements is the basis of our modern periodic table We will explain the reason for these trends later on

PERIODIC TABLE Use your periodic table to take notes Periodic table is divided into columns and rows Columns are called GROUPS. Groups have elements with similar properties. Rows are called PERIODS. Periods have elements with similar electron configuration.

METALS VS. NONMETALS Look at the periodic table at the front of the class. Find the red “stair shaped” line located at the right of the list. It starts with B (boron) This divides the metals (to the left of the line); and The nonmetals (to the right of the line) Note this line on your periodic table

METALS VS. NONMETALS Metals: Good conductors of heat and electricity Malleable: can be pounded flat Ductibility: can be drawn into wires Often shiny Tend to lose electrons in chemical reactions Transition metals: the metals locate in group 3 -12

NONMETALS Nonmetals: Poor conductors of heat and electricity Much more varied properties than metals Some are solids and some are gases at room temperature Tend to gain electrons in chemical reactions

METALLOIDS (SEMICONDUCTORS) Elements located near the line dividing metals and nonmetals are sometimes called semiconductors or metalloids: Boron (B) Silicon (Si) – very important for computers Germanium (Ge) Arsenic (As) Antimony (Sb) Tellurium (Te) Astatine (At)

METALLOIDS Metalloids have intermediate conductivity for electricity This conductivity can be changed and controlled Very useful for the binary language of computers

MAIN GROUP ELEMENTS Main group elements: These elements have predictable behaviors based on their position on the periodic table. Predictability is based on the GROUPS, or the columns in the Periodic table

GROUP 1 (OR IA) Group 1 is located in column 1. This group is called the Alkali metals are very active metals For example: Pure sodium added to water creates a huge explosion. Alkali metals are soft and can be cut with a knife When they undergo chemical reactions, they tend to lose 1 electron and produce a (+1) charge

GROUP 2 (OR IIA) Group 2 is located in column 2. This group is called the Alkali earth metals are fairly reactive, but not as reactive as Alkali metals For example: Magnesium gives off a very bright, white light when lit. Harder, denser and stronger metals When they undergo chemical reactions, they tend to lose 2 electron and produce a (+2) charge

GROUP 7 (OR VIIA) START HERE Group 7 is located in column 17. This group is called the Halogens Very reactive nonmetals Often gaseous at room temperature Elements are often used to sterilize (chlorine or bromine in pools; fluorine in the water) When they undergo chemical reactions, they tend to gain 1 electron and produce a ( -1) charge

GROUP 8 (OR VIIIA) Group 8 is located in column 18. This group is called the Noble Gases Chemically inert (does not undergo chemical reactions) For example: Balloons now use Helium gas instead of Hydrogen Noble gases do not gain or lose electrons without lots of energy

LATHANIDES Have atomic numbers from 58 -71 Elements that come after the element, Lanthanum (La) Shiny, reactive metals Irregular electron configurations

ACTINIDES Have atomic numbers from 90 -103 Elements that come after the element Actinium (Ac) All actinides are radioactive Example: Nuclear fission of uranium produces a large amount of energy as produced in a nuclear missile or atomic reactor.

TRANSITION METALS Not as predictable in how they behave They may lose different number of electrons in reactions Example: Iron can lose 2 or 3 e- in a reaction and make Fe+2 Fe+3

MAKE SURE YOU HAVE LABELED YOUR PERIODIC TABLES Have the following groups Metals/Nonmetals/Metalloids Alkali metals Alkali earth metals Halogens Noble gases Also the following periods Lanthanides Actinides Transition metals