In 1869, Russia's Dmitri Mendeleev and Germany'sLothar Meyer...

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Meyer Mendeleev

published nearly identicalclassification tables for the 63elements known at the time...

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Meyer Mendeleev

based on recurring chemicaland physical properties whenelements were arranged...

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Meyer Mendeleev

in order of increasingatomic weight.

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Meyer Mendeleev

Mendeleev

Although their observationswere identical, Mendeleev isgiven the credit becausehe predicted theexistence ofundiscoveredelements and leftspaces for them.

Mendeleev's table, published in the journal Annalen der Chemie in 1871.

Mendeleev isknown as the Father of the Periodic Table.

And almost no one outside ofGermany knows about Meyer.

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In 1913, Henry Moseleydeveloped the concept of atomic numbers.

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Moseley correctly saidthat the atomicnumber wasequal to thenumber ofprotons in thenucleus...

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AND the numberof electrons inthe atom.

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When Moseley arrangedatoms by their increasingatomic number,the few problems with Mendeleev's table disappeared.

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In 1945, Glenn Seaborgproposed pulling the lanthanide and actinideseries out ofthe main bodyof elements onthe table.

Seaborg

Elements on today's periodic table are arranged byincreasing atomic number...

the lanthanide and actinide series are separated from the main body...

f block

AND the d block elements...

separate the main body elements.

s block p block

Every element is representedby a single square.

Each square containsthree things:

1. The chemical symbol for the element.

If there are two letters,the first is ALWAYSa capital letter, and the second is ALWAYSa small letter.

1. The chemical symbol for the element.

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Solid

The symbols on some tables indicate the physical state at room temperature.

Liquid Gas

2. A whole number representing the atomic number.

The atomic number is notalways in the sameplace on everyperiodic table -but it is ALWAYSa whole number.

2. A whole number representing the atomic number.

The atomic number is definedas the number ofprotons in the atom.

2. A whole number representing the atomic number.

Normal atoms have an equalnumber of protonsand electrons - so,the atomic numberis also equal to theelectrons in an atom.

2. A whole number representing the atomic number.

Chemists can change thenumber of electrons inan atom, but theycan NOT change thenumber of protonsin an atom.

2. A whole number representing the atomic number.

Changing the number ofprotons changes theelement into anotherelement - this canonly happen in anuclear reaction.

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3. A decimal fraction number representing the element's average atomic mass.

3. A decimal fraction number representing the element's average atomic mass.

The atomic massof an element isthe sum of itsprotons andneutrons.

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

How manyneutrons?

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

0

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

How manyneutrons?

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

1

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

How manyneutrons?

Atoms of an element all havethe same numbers of protons,but they can have differentnumbers of neutrons.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

2

Atoms of the same elementwith different numbers of neutrons are called isotopes.

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

Which of hydrogen's threeisotopes is the most common?

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

Which of hydrogen's threeisotopes is the most common?

H1

1.00794

Hydrogen-1Hydrogen-2Hydrogen-3

Round off all mass numbersto the nearest WHOLE number.

Isotopes

More information onthe Periodic Table

The Nobel GasFamily ischemicallyinactive.

Fluorine is the most active nonmetal

Francium is the most active metal

The oxidation number of an element indicates the number of electrons gained or lost when forming compounds.

Elements with positive oxidation numbers lose electrons.

Elements with negative oxidation numbers gain electrons.

+1

+2

+1, +2, +3

+3

+4 or -4

-3

-2

-1

Electron energy levels, from 1 to 7

Electron energy sublevels

Electron energy sublevel s

Electron energy sublevel p

Electron energy sublevel d

Electron energy sublevel f

Each "pair" of boxes in a sublevelindicates an orbital.

Vertical columns are Families -

elements with similar properties.

Alkali Metals

Alkaline Earth Metals

Transition Metals

Rare Earth Metals

Boron Family

Carbon Family

Nitrogen Family

Oxygen Family

Halogen Family

Nobel Gas Family

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The Periodic Table - 27 min

Size of a Molecule

An Electron Configuration showsthe exact location of every electronin an atom.

With very few exceptions, theelectron configuration of an atomcan be read directly from the Table.