Trends in 3rd Period

8/6/2019 Trends in 3rd Period

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Third-Period Trends

Monday, August 15, 11



Elements in the 3rd Period

SodiumMagnesium

AluminumSilicon

Phosphorus

Sulfur ChlorineArgon




Trends in what?In their chemical reaction with OXYGEN, WATER,AND CHLORINE







Some Observations

• The elements are arranged according to

increasing proton number. (valence electrons

increase).

• Atomic radii decrease (smaller volume).

• Ionization energies increase.

• Elements become less metallic.




Some Observations

• Na, Mg, and Al have good thermal and

electrical conductivities. The metalloidSi is only a fair conductor of heat andelectricity, while the nonmetals P, S, Cl,

and Ar are poor conductors.• Metallic property decreases.




Some Observations

• Their valence electrons occupy the 3sand 3p orbitals.

• Electronegativity increases. (tendencyof atoms to attract electrons towardsitself)

• Elements in each period have electronsin the same outer shell.



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It requires more energy to strip an electronfrom the lower energy 3s orbital in Mg than

from a half-filled 3p orbital in Al.




The Melting and BoilingPoints




Explanation

• Melting: it depends on the attractive

forces holding the particles together

whether or not the particles can beseparated easily or not (needed energy)

• Boiling: similar to melting, the

attractive forces on the particles (more

energy or not)




Melting, Boiling, Hardness

• depends on the strength of the

attractive forces acting upon the atom






Structure AFFECTS meltingand boiling points.




amphotericGreek word “amphos”Meaning: both




metallic bonds (Na, Mg, Al)covalent bonds (Si)

intermolecular forces (P, S, Cl, Ar)




The Forces

• Metallic Bonds (Na, Mg, Al) - become

stronger, hence increasing melting and

boiling points

• Covalent (Si) - crystalline solid

• Intermolecular forces - attractive forces become progressively weaker






Definitions

• Oxide: a binary compound of oxygenwith another element or group

• Chloride: a compound of chlorine with

another element or group








Oxides






Silicon oxide:

diamond-likemacromolecular structure with a

high melting and

boiling point


hl d



Chlorides





d hl d d



Aluminumchloride possesses

a much morecovalent

character.

Sodium chloride and magnesiumchloride are ionic and still haverelatively high melting points.

The three remainingchlorides are held

together by weak van

der Waal’s forces,therefore low meltingand boiling points.

van der Waals forces |ˈvan dər

ˌwôlz, -ˌvälz|

pluralnounChemistry

weak, short-range electrostaticattractive forces betweenuncharged molecules, arising from the interaction of permanent or transient electricdipole moments.




• Sodium chloride (only neutral chloridein Period 3 - gives a pH of 7 when

dissolved in distilled water)

• Magnesium chloride gives a slightlyacidic solution with distilled water (Mg

ion is small, and charge of +2 - density

of the charge of the ion is much higherthan that on a sodium ion)




• Aluminum chloride (no water or

anhydrous), when added to water,

gives an exothermic reaction and HCl is

produced.

• Chlorine reacts with water to form an

acidic solution.

Cl 2 (aq)+ H 2O(l ) HCl (aq) + HClO(aq)




Reference Sources• http://scienceaid.co.uk/chemistry/inorganic/period3.html

• http://www.docbrown.info/page07/ASA2ptable5b.htm

• http:/ /www.chemguide.co.uk/ inorganic/per iod3/oxidesphys.html

• http://chemistry-helper.blogspot.com/2011/04/3-periodicity-sl.html

• http://sandblastingabrasives.com/aluminum-oxides-3/

• http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html


http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/bond.html



http://sandblastingabrasives.com/aluminum-oxides-3/

http://www.chemguide.co.uk/inorganic/period3/oxidesphys.html




http://www.docbrown.info/page07/ASA2ptable5b.htm

















http://scienceaid.co.uk/chemistry/inorganic/period3.html

http://scienceaid.co.uk/chemistry/inorganic/period3.html



Reference Sources

• http://www.ausetute.com.au/trendpd3.html

• http://www.chemguide.co.uk/inorganic/period3/

elementsphys.html• http://ibchem.com/IB/ibnotes/brief/per-hl.htm#pert

• http://www.creative-chemistry.org.uk/alevel/

module1/trends8.htm• h t t p : / / c h e m i s t r y . a b o u t . c o m / o d /

periodictableelements/a/periodictrends.htm


http://chemistry.about.com/od/periodictableelements/a/periodictrends.htm


http://www.creative-chemistry.org.uk/alevel/module1/trends8.htm


http://ibchem.com/IB/ibnotes/brief/per-hl.htm#pert

http://www.chemguide.co.uk/inorganic/period3/elementsphys.html
















http://www.ausetute.com.au/trendpd3.html

http://www.ausetute.com.au/trendpd3.html



Reference Sources• http://www.chemguide.co.uk/atoms/structures/

period3.html

• http://www.avon-chemistry.com/p_table_lecture.html

• http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Electronic_Configurations

• http://chemwiki.ucdavis.edu/Inorganic_Chemistry/

D e s c r i p t i v e _ C h e m i s t r y /P e r i o d i c _ T a b l e _ o f _ t h e _ E l e m e n t s /Periodic_Properties_of_the_Elements

• h t t p : / / w w w . e n i g m a t i c - c o n s u l t i n g . c o m /

http://www.enigmatic-consulting.com/semiconductor_processing/CVD_Fundamentals/films/SiO2_properties.html

http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Table_of_the_Elements/Periodic_Properties_of_the_Elements




http://chemwiki.ucdavis.edu/Inorganic_Chemistry/Electronic_Configurations


http://www.avon-chemistry.com/p_table_lecture.html

http://www.chemguide.co.uk/atoms/structures/period3.html





















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Trends in 3rd Period

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