Notes on the History of the Periodic Table in the Unit Note Packet

Objectives C.2.1 Periodic Table Students understand that the periodic table is an organizational tool that can be used for the prediction and classification of the trends and properties of elements.

5.1 ORGANIZATION OF THE PERIODIC TABLE AND ELEMENT CLASSIFICATION In the 1860’s___Dmitri___Mendelev___ organized the first periodic table by MASS. He recognized that when elements were arranged in order of increasing mass, certain similarities in their chemical properties appeared at regular intervals. Such a repeating pattern is referred to as perioidic. In about 1916, ____Robert___ Mosely___ organized elements by ATOMIC NUMBER because he recognized that periodic patterns were better fit for all known elements when organized by increasing number of nuclear charge, i.e. the number of protons. The modern periodic table orders elements by ATOMIC NUMBER. Periodic Law – The physical and chemical properties of the elements are periodic functions of their atomic number.

Groups (Families) Groups (Families) VERTICAL columns Designated by numbers ___1___ – ___18___ The Group number “ONE’s” place represents the # of _Electrons_ electrons an atom possesses. This applies to groups 1, 2, and 13-18 only. Example: all elements in group 16 have 6 valence e– Valence electrons are electrons in the OUTERMOST ENERGY LEVEL of an atom. They are responsible for _Bonding_. As you go DOWN each level in a group, an ENERGY LEVEL is added to the atom. Elements in a group have similar _Chemical_ and _Physical_ properties

Periods Periods Designated by numbers __1___- ___7___ HORIZONTAL rows Period number represents in general the number of ENERGY LEVELS Energy Level – the space around an atom’s nucleus where electrons are found based on the amount of energy they possess. From LEFT to RIGHT in a period, each element gains ___1__ proton and ___1__electron. _Properties_ change from left to right

Zig-Zag Line Separates __Metals (on the left) from __Nonmetals___ (on the right

Metals and Nonmetals Metals – tend to LOSE electrons (e–) to form CATIONS (+ charge) Cation – atom that has __Lost____ one or more electron(s) Nonmetals – tend to GAIN electrons (e–) to form ANIONS (- charge) Anion – atom that has _Gained____ one or more electron(s

Metalloids Metalloids – have properties of metals and nonmetals. found along and to either side of the zig-zag line (except __Al___ ) mostly brittle __Solids____ Metalloids are semiconductors which means they conduct electricity, but not heat. Uses: computer chips (silicon) and eyewash (boron).

Metalloids Metalloids

REPRESENTATIVE (Groups 1, 2, 13 – 18)

Alkalai Metals cont. ALKALI METALS (Group _1__) __1_____ valence electron. will lose 1 e– to form the _+1____ cation The oxidation state is therefore __+1___ Very REACTIVE, never found “_free____” (uncombined) in nature Chemical property – most reactive metal, reacts with _H2O______ Physical property – __Soft_____, silvery metal Uses – batteries, nuclear reactors, table salt, medicines.

Alkalai Earth Metals ___2_ valence electrons. will give up 2 e– to form _+2 cation The oxidation state is there __+2_ Reactive, never found “free_” in nature Uses: Mg – corrosion protection, Sr – fireworks

Halogens HALOGENS (Group __17____) ___7___ valence electrons gains 1 e– to form ___-1_ anion The oxidation state is therefore _-1_ Most __reactive_ _ of all nonmetals Uses: Cl - pool purification, I - iodized salt, F - dental health

Noble Gases NOBLE GASES (Group _18) _8_ valence e– (except He) Full outermost energy level __Not__ reactive Uses: He - balloons, Ne – signs

Group 13-16 Named for the FIRST element in each group, for example, group 13 is called the “_oxygen_” group. Properties vary depending on group.

TRANSITION Metals (Groups _3____ – _12____) The commonly known “metallic” elements Multiple ___oxidation_______ states, which means they can lose a ___varying_ number of electrons. Many are __brightly_ colored o Uses: Fe - steel, Au/Ag – jewelry

INNER TRANSITION Metals Lanthanide and Actinide series Lanthanides (Ce to Lu) are _silvery_, high-melting point, very valuable metals. Uses: lanthanides – glass industry, cell phones Actinides (Th to Lr) are _radioactive_, Uses: nuclear fuel, nuclear medicine, research

The End Test on 12/17/2015