Periodic Table and Trends

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