PERIODIC TABLEPERIODIC TABLE

•(1869) Dmitri Mendeleev(Russian chemist) shows a first version of the periodic table. •He noticed that classifying the elements by their atomic mass a periodicity in certain properties could be seen. The first table consisted of 63 elements. •Periodicity: the regular repeating of properties according to the arrangement of elements in the PT.

**Henry Mosely(British) Henry Mosely(British) discovered nuclear charges discovered nuclear charges of all known elements and of all known elements and that chemical properties of that chemical properties of

elements are related to elements are related to their their atomic numbers atomic numbers but but

not atomic weights.not atomic weights.

He stated that elements He stated that elements should be arranged in should be arranged in

order of increasing order of increasing atomic atomic numbersnumbers..

So, today’s periodic table So, today’s periodic table was formed.was formed.

In modern periodic table, In modern periodic table, elements are listed in order elements are listed in order

of of increasing atomic increasing atomic numbersnumbers..

Elements with Elements with similar similar chemical properties chemical properties are are

placed in the placed in the same vertical same vertical columnscolumns..

1A:1A: Alkali metalsAlkali metals2A:2A: Alkaline earth metalsAlkaline earth metals

3A:3A: Earth metalsEarth metals7A:7A: HalogensHalogens

8A:8A: Noble(Inert)gasesNoble(Inert)gases

GROUPS/FAMILIES:GROUPS/FAMILIES: The vertical columnsThe vertical columns Elements Elements in the same group in the same group have have

--similar chemical similar chemical propertiesproperties(exception:(exception:

H in 1A group)H in 1A group)

-Same number of -Same number of valence electronsvalence electronsand orbitals.(exception:He in 8A and orbitals.(exception:He in 8A

group)group)

GROUPS/FAMILIES:GROUPS/FAMILIES:

--similar chemical similar chemical propertiesproperties(exception:(exception:H in 1A group)H in 1A group)

For example, all 1A metals react For example, all 1A metals react vigorously with water.vigorously with water.

****For A groups; For A groups; # of valence # of valence

electrons= # of the groupelectrons= # of the group((except except He in 8AHe in 8A))

in 7A;number of valence in 7A;number of valence electrons=7electrons=7

PERIODS:PERIODS:

The horizontal rowsThe horizontal rows There are 7 periods There are 7 periods Valence shellValence shell determines the period determines the period

numbernumber Each of them Each of them starts with a metal and starts with a metal and

ends with a noble gasends with a noble gas.(except first .(except first and seventh ones)and seventh ones)

Elements Elements in the same period in the same period have the have the same # of energy levels or shells same # of energy levels or shells or or principle quantum numbers.principle quantum numbers.

Metals lie to the left of the zig-zag line.Nonmetals lie to the right of the zig-zag line.

Over 80 % of the known elements are metals.

Differences between Metals Differences between Metals and Nonmetalsand Nonmetals::

Metals always lose electrons in compounds.

The ease with losing an electron forms the metallic character of elements.

Tendecy in gaining electrons forms the nonmetallic character.

PROPERTIES OF METALS Conduct the heat and electricity in their molten(liquid)

and solid states. Solid at room conditions except Hg. Always lose electron in chemical rxns.Thus, they can

only form CATIONS. Ductile(can be drawn out to make wires) and

malleable (can be beaten into sheets). Have lustre (shiny) appearance. Have high melting points.

PROPERTIES OF METALS

Sonorous (Make a ringing noise when struck) Have high density. Hard (except some metals: Na, Mg) Cannot form compounds w/ each other. Instead, they

can only form homogeneous mixtures called “alloys.”(e.g., bronze, stel, solder, brass)

PROPERTIES OF NONMETALS do NOT conduct the electricity, except

graphite(C). can be solid, liquid, or gas at room

conditions. This shows that they have lower melting points than metals.

Tend to gain electrons or share electrons in their compounds.Therefore, the form negative (ANIONS) ions in compounds (except H, which can also be H+).

PROPERTIES OF NONMETALS

Solid nonmetals have lower density compared to metals.

are brittle. have dull appearance.

Which ones of these properties of Which ones of these properties of metals and nonmetals are metals and nonmetals are physical /chemicalphysical /chemical??

Increasing nonmetallic character(Except 8A)

Incre

asi

ng

non

meta

llic

ch

ara

cte

r

Metallic and Nonmetallic activity

-Metallic activity decreases-Nonmetallic activity increases-Metallic

activity increases-Nonmetallic activity decreases

Which elements are the most Which elements are the most reactive metals and reactive metals and nonmetals in the periodic nonmetals in the periodic table?table?

Francium(Fr) and Cesium(Cs) Francium(Fr) and Cesium(Cs) in 1A are the most reactive in 1A are the most reactive metals.metals.

Fluorine(F) in 7A is the most Fluorine(F) in 7A is the most reactive nonmetal.reactive nonmetal.

Important Groups

Each Each NNoboblele gas has gas has 8 valence 8 valence electronselectrons in their outer shellsin their outer shells,except ,except HeHe.. He He has has 22 valence electrons. valence electrons.

Because of their Because of their STABLE ELECTRON STABLE ELECTRON ARRANGEMENTSARRANGEMENTS, they, they are stable and are stable and UNREACTIVEUNREACTIVE!!

All other elements try to have the All other elements try to have the electron arrangement of Noble gases electron arrangement of Noble gases in their compounds.in their compounds.

GROUP 0- A SPECIAL GROUP 0- A SPECIAL GROUP!!!GROUP!!!

NOBNOBLELE (Inert)(Inert)GASES(VIIIA):GASES(VIIIA):

They are gaseous at room They are gaseous at room

conditions.conditions.

The Nobel gases are used in neon The Nobel gases are used in neon signs.Each nobel gas glows a signs.Each nobel gas glows a different colour when electricity is different colour when electricity is passed through it.passed through it.

For instance, Helium glows For instance, Helium glows pink,neon glows orange-red, and pink,neon glows orange-red, and argon glows purple.It isn’t just neon argon glows purple.It isn’t just neon in those signs!in those signs!

Jellyfish lamps made with noble gases

OXIDATION STATES OF OXIDATION STATES OF ELEMENTSELEMENTS

Oxidation state (or valency) is the Oxidation state (or valency) is the positive or negative chargepositive or negative charge that that an atom gets when it forms a an atom gets when it forms a compound.compound.

OXIDATION STATES OF OXIDATION STATES OF ELEMENTSELEMENTS

Group

IA IIA IIIA IVA VA VIA VIIA

VIIIA

MAX(+)

+1 +2 +3 +4 +5 +6 +7 NA

MIN(-)

NA NA NA -4 -3 -2 -1 NA

References References

http://www.youtube.com/watch?v=m55kgyApYrY(Date of accession: 14/11/2011) of accession: 14/11/2011)