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