THE MODERN PERIODIC TABLE

Mendeleev                     1834 - 1907 1869 – Dmitri Mendeleev published the first periodic table

Mendeleev Born in Siberia, the last of 14-17 children Father blind, mother ran glass factory When he finished high school, his father died and the factory burnt down

Mendeleev His mother took him to St. Petersburg to study science Denied admission to the university, he studied at a school for teachers

Mendeleev In time, he became a professor of chemistry at the U. of St. Petersburg While writing a chemistry textbook, he developed the periodic table

Mendeleev Where a gap existed in his table, he predicted a new element would be found and deduced its properties He was right. Three elements were found during his lifetime Ga, Sc, Ge

Mendeleev The discovered elements provided the strongest support for his periodic table It is a cornerstone in chemistry and in our understanding of how the universe is put together

Mendeleev Mendeleev’s table arranged the elements in order of increasing atomic mass

Henry Moseley 1887 - 1915 Studied atomic structure As a result, the periodic table was rearranged in order of atomic number Killed in action at Gallipolli (WWI) in 1915 at age 28; a great loss for science

Modern Periodic Table

Modern Periodic Table Square of the periodic table contains an                                                                                                                       Square of the periodic table contains an element’s atomic #, chemical symbol, atomic mass

Modern Periodic Table An element’s properties can be predicted from its location in the periodic table The elements in each group have the same number of valence electrons

METALS Most elements are metals 88 elements to the left of the “staircase” are metals or metal like elements

Physical Properties of Metals Luster (shininess) Good conductors of heat and electricity High density (heavy for their size) High melting point Some metals (Fe, Co and Ni) are magnetic

Physical Properties of Metals Ductile (most metals can be drawn out into thin wires) Malleable (most metals can be hammered into thin sheets)

METALS

Chemical Properties of Metals Metals show a wide range of chemical properties Reactivity – ease and speed with which an element combines, or reacts with other elements and compounds

Chemical Properties of Metals Some metals are very reactive, some do not react easily Alloy – mixture of metals Examples: bronze, brass, stainless steel

Chemical Properties of Metals Easily lose electrons Corrode easily. Corrosion is a gradual wearing away Examples of corrosion: silver tarnishing and iron rusting

Chemical Properties of Metals Metal atoms give up outer electrons easily When many atoms are combined, they “share” electrons Metal atoms slide past each other, held together but not locked in place Result? Malleable, ductile, conduct electricity

Families of Metals

Group 1 – Alkali Metals

Group 1 – Alkali Metals One valence electron Li Most reactive Soft Low densities Low melting point Li Na

Group 1 – Alkali Metals Combine with negative ions to form salts

Group 1 – Alkali Metals Na, K Na compounds in large amounts in sea water Na and K both essential for life

Group 1 – Alkali Metals

Group 2 – Alkaline Earth Metals Two valence electrons Very reactive

Group 2 – Alkaline Earth Metals Magnesium and calcium are common alkaline earth metals Calcium compounds make up much of your bones and teeth

Group 2 – Alkaline Earth Metals Magnesium, when combined with aluminum, makes a strong but lightweight alloy

Group 2 – Alkaline Earth Metals

Transition Metals

Transition Metals Elements in Groups 3 – 12 Bridge between very reactive metals on left side and less reactive metals on the right side

Transition Metals Transition metals are fairly stable React slowly or not at all

Rare Earth Metals Lanthanides and Actinides Lanthanides are soft, shiny metals with high conductivity Actinides are all radioactive. Some not found in nature

NONMETALS Nonmetals are found to the right of the stair step line 17 elements Make up most of the human body

Physical Properties of Nonmetals The physical properties of nonmetals are opposite to those of metals

Physical Properties of Nonmetals No luster (dull appearance) Poor conductor of heat and electricity Brittle (breaks easily) Not ductile Many are gases at room temperature

Physical Properties of Nonmetals Not malleable Low density Low melting point Elements in this group have one valence electron How does this affect their reactivity? It makes them VERY REACTIVE.

Chemical Properties on Nonmetals Have many electrons in their highest energy level Form negative ions Gain electrons Noble gases do not react with other elements

Chemical Properties of Nonmetals Tend to gain electrons React with metals to form salts React with other nonmetals and share electrons

Chemical Properties of Nonmetals Diatomic molecule – when nonmetals form molecules of two identical atoms H H

METALLOIDS Elements that border the zigzag line have properties of both metals and nonmetals These elements are called metalloids.

Physical Properties of Metalloids Solids Can be shiny or dull Ductile Malleable Conduct heat and electricity better than nonmetals, but not as well as metals

Physical Properties of Metalloids Some are semiconductors, such as Si (silicon)

Ionic Compounds Since metals tend to lose electrons and nonmetals tend to gain electrons, metals and nonmetals like to form compounds with each other These compounds are called ionic compounds

Boron Group Boron is the only element in group 13 that is not a metal B is brittle, black metalloid Al is the most abundant metal in the earth’s crust Aluminum has many uses

Carbon Group Carbon is the only nonmetal in Group 14 Two common forms – graphite and diamond Each element has four valence electrons                                                                                 

Group 14 – Carbon Group Carbon is the element essential for life It is unique because it can link up with other C atoms to form long chains                           

Carbon Group Si and Ge are metalloids Sn and Pb are metals

Group 15 – Nitrogen Group N and P are nonmetals N makes up 80% of air N is essential to life N-fixing bacteria take N from air and change into compounds plants can use

Group 15 – Nitrogen Group P (Phosphorus) also necessary for life P in bones, teeth and DNA As and Sb are metalloids

Group 16 – Oxygen Group O is the most abundant element on earth O is very reactive and can combine with almost every other element S, Se are also nonmetals

Group 17 -- Halogens Halogen means “salt-former” Halogens combine with metals to form salts Have 7 valence electrons F is the most reactive nonmetal

Group 18 – The Noble Gases Colorless gases Do not combine with other elements Outer electron shell is full

Group 18 – The Noble Gases He is the second lightest gas

Hydrogen H does not fit in with any group Reacts easily with other elements Can act like a metal or a nonmetal

QUIZ YOURSELF! What are the rows across the periodic table called? Answer: PERIODS                                                                              

QUIZ YOURSELF! What is the term for the vertical columns in the Periodic Table? Answer: Groups or Families                                                                              

QUIZ YOURSELF! How are the elements arranged in the periodic table? In order of increasing atomic number                                                                                                                      

QUIZ YOURSELF! ALKALI METALS -- GROUP 1 What is the most reactive group of metals? ALKALI METALS -- GROUP 1