Johann Dobereiner (1780-1849)

• In 1829, classified some elements into groups of three (He called them triads)

• The elements in the triads had similar chemical properties & orderly physical properties

• Model of Triads

John Newlands (1839-1898)

• In 1863, he suggested that elements be arranged in “octaves”

• He noticed (after arranging the elements in order of increasing atomic mass) that certain properties repeated every 8th element

• Law of Octaves

• Claimed to see a repeating pattern was met with savage ridicule on its announcement

• His classification of the elements was as arbitrary as putting them in alphabetical order and his paper was rejected for publication by the Chemical Society

Dmitri Mendeleev

• A Russian Chemist and Inventor

• Published the periodic table in the form we use today

• His periodic table grouped similar elements into columns (Just like ours does today)

Lothar Meyer (1830-1895)

• At the same time as Mendeleev, he published his own table of elements

• He organized the elements by increasing atomic mass

Periodic Table

• Elements on the table can be divided into three main categories: Metals, Non-Metals, and Metalloids

• The periodic Repetition of chemical properties is the result of the arrangement of electrons in the outer energy level (Valence Electrons)

• Variations in physical properties are due to different atomic numbers (Protons)

• Elements on the periodic table can be grouped into families based on their chemical properties

• Each family has a specific name to differentiate it from the other families in the periodic table

• Elements in each family react differently with other elements

• The horizontals rows are called periods and are labeled 1 to 7

• the vertical columns are called groups/families and are labeled 1 to 18

Metals

• Solid at room temperature (Except for Mercury - it is a liquid)

• Shiny lustre

• Good conductors of heat and electricity

• Malleable

• Ductile

Non-Metals

• They are a gas or a solid at room temperature (Bromine is the only one that is a liquid)

• Not very shiny

• Poor conductors of heat and electricity

• Brittle

• Not ductile

Metalloids

• Solid at room temperature

• Can be shiny or dull

• May conduct electricity

• Poor conductors of heat

• Brittle

• Not ductile

Families

• Hydrogen - Belongs to family of its own; a diatomic reactive gas; involved in the explosion of the Hindenburg; promising as an alternative fuel source for automobile

• Alkali Metals - Hydrogen is not a member, it is a non-metal; 1 electron in the outer shell (One valence electron); soft silvery metals; Very reactive, especially with water; conduct electricity

• Alkaline Earth Metals - 2 electrons in the outer shell (Two valence electrons); white and malleable; reactive, but less than Alkali metals; conduct electricity

• Transition Metals - Good conductors of heat and electricity; some are used for jewelry; the transition metals are able to put up to 32 electrons in their second to last shell; can bond with many elements in a variety of shapes

• Boron Family - 3 electrons in the outer shell (three valence electrons); most are metals; Boron is a metalloid

• Carbon Family - 4 electrons in the outer shell (four valence electrons); Contains metals, metalloids, and a non-metal (carbon) (C)

• Nitrogen Family - 5 electrons in the outer shell (five valence electrons); can share electrons to form compounds; contains metals, metalloids, and non-metals

• Oxygen Family (Chalcogens) - 6 electrons in the outer shell (six valence electrons); contains, metals, metalloids, and non-metals; reactive

• Halogens - 7 electrons in the outer shell (seven valence electrons); all are non-metals; Very reactive are often bonded with the elements from Group 1

• Noble Gases - Exist as gases; non-metals; 8 electrons in the outer shell = Full; Helium (He) has only 2 electrons in the outer shell = Full; Not reactive with other elements

• Rare Earth Metals (Lanthanide & Actinide) - Some are radioactive; silver, silvery-white, or grey metals; conduct electricity

Ions

• When an atom loses or gains electrons

• Cations are positive and are formed by elements on the left side of the periodic chart

• Anions are negative and are formed by elements on the right side of the periodic chart

Zeff

• Typically refer to the effective nuclear charge

• Increase to the right

• Increases going up

Atomic Radii

• Half the distance between the nuclei of identical atoms that are bonded together

• Defined by the edge of its orbital but since the edges are fuzzy, it is difficult to determine

Atomic Size

• Increase size going down

• Decrease size going to the right

• Electrons are in the same energy level

• But, there is more nuclear charge

• Outermost electrons are pulled closer

Ionization Energy (Ei)

• Minimum energy required to remove an electron from the ground state of atom (molecule) in the gas phase

• Frist Ionization Energy - the energy needed to remove the outermost electron from an atom

• Second Ionization Energy - the energy needed to remove the second electron from an atom, etc.

• The greater the nuclear charge, the greater IE

• Greater distance from nucleus decreases IE

• Increases moving to the right

• Increases going up (If it moves down the electron is further away from the nucleus, having less pull on it)

• 

Electronegativity

• Measure of an attraction of an atom for a shared electron

• Electronegativity is the tendency for an atom to attract electrons to itself when it is chemically combined with another element

• An element with a big electronegativity means it pulls the electron towards itself strongly!

• This is the small table on the back of your periodic table

Ionic Radius

• The element’s share of the distance between neighboring ions in an ionic solid

• Generally: Cations are smaller than their parent atoms and Anions are larger than their parent atoms

Electron Affinity

• The energy change associated with the addition of an electron

• Increases going the right

• Increase going up