UNIT# 04

ARRRANGEMENT OF ELEMENTS

After the discovery of many elements, it was necessary to arrange them in a table. Thus, work started slowly but successfully and after almost period of 85 years, a table was designed for the simplest study of elements. The table was arranged on the basis of atomic masses of the elements.

Q#	Questions	Year
Q#01	State Law of Triad.	[2017][2016][2011] [2010][2009][2007]
Q#02	State Law of Octave.	[2017][2016][2011] [2009] [2007]
Q#03	State Henry’s law.	[2015]
Q#04	State Mendeleev’s periodic law.	[2007][2006]
Q#05	State Modern periodic law.	[2017][2016][2015] [2011] [2009] [2007]
Q#06	Describe the salient features of Mendeleev’s periodic table.	[2018] [2014] [2006]
Q#07	What are the elements of group IA called?	[2016]
Q#08	Define periodicity.	[2012] [2007]
Q#09	Describe the general characteristics of group IA.	[2011][2010][2016] [2012]
Q#10	Describe the general characteristics of group VIA.	[2016][2015][2011] [2009] [2007][2005]
Q#11	Describe the general characteristics of Transition elements.	[2017][2014][2012] [2011] [2010]
Q#12	Differentiate between metals, nonmetals.	[2015][2014] [2011][2012][2010] [2009] [2008] [2006]
Q#13	Define metalloid.	[2014] [2011][2008][2006]
Q#14	Which elements have zero valences? In which group of the periodic table has been they placed? Also give their two examples.	[2013]
Q#15	How many periods and groups are there in the modern periodic table? Also state what are the Lanthanide and Actinides?	[2013]
Q#16	Discuss Ionic radii with reference to group trend.	[2014][2011][2007] [2005]
Q#17	Discuss Ionization energy with reference to group trend.	[2011] [2007] [2005]
Q#18	Discuss Ionization Potential with reference to group trend.	[2007]
Q#19	Discuss Electron affinity with reference to group trend.	[2018] [2008] [2007]
Q#20	Discuss Electro negativity with reference to group trend.	[2018][2014][2011] [2005]

Q. What do you know about Al Razi’s classification?

AL RAZI’S CLASSIFICATION

AL Razi classified the elements into metal, nonmetals and derivatives based upon their physical and chemical properties.

Q. State law of triad with example.

LAW OF TRIAD

STATEMENT

In 1829, Dobereiner arranged similar chemical properties having elements in a group of three because of what it is called Law of triad.

“Central atom of each set of triad had an atomic mass equal to the arithmetic mean of the atomic masses of the other two elements.”

FOR EXAMPLE

Elements	Atomic mass	Arithmetic mean	Mean
Lithium	07	7+39 2	23
Sodium	23
Potassium	39

Elements	Atomic mass	Arithmetic mean	Mean
Chlorine	35.5	35.5 + 127 2	81
Bromine	80
Iodine	127

Law of triad was failed, because it was applicable in only few cases.

Q. State law of octave with example.

LAW OF OCTAVE

STATEMENT

In 1864, Newland arranged the eight elements on the basis of their chemical properties.

“If elements are arranged in order of increasing atomic masses the eighth element starting from the given one have similar chemical properties as the first one.”

FOR EXAMPLE

DISCREPANCIES

· He totally ignored the ideal gases

· Hydrogen was not included in this sequence

Q. State Lothar Meyer’s classification.

LOTHAR MEYER’S CLASSIFICATION

In 1869, Lothar Meyer arranged 56 elements in the periodic table. He also calculated the atomic value of elements

ATOMIC VOLUME

The volume occupied by the 01 gram atomic weight of atoms of element is known as atomic volume.

Q. State Mendeleev’s classification.

MENDELEEV’S CLASSIFICATION

“The physical and chemical properties of the elements are the periodic function of their increasing atomic weights.”

Q. Give the advantages of Mendeleev’s periodic table.

ADVANTAGES OF MENDELEEV’S PERIODIC TABLE

1. It helped the systematic study of elements.

2. Prediction of new elements were made possible

3. It helped in correction of many doubtful atomic masses.

4. He arranged the elements in eight vertical columns called group and twelve horizontal rows called period.

5. Group number indicates the valence number.

Q. Give the disadvantages of Mendeleev’s periodic table.

DISADVANTAGES OF MENDELEEV’S PERIODIC TABLE

1. He did not left spaces for the isotopes.

2. Dissimilar atoms were placed in the same group like alkali metals were placed with coinage metals.

3. It failed to give the idea of the atomic structure.

4. Positions of Lanthanide and actinide series were assigned in similar places.

5. He placed elements of higher atomic weights before the lower masses kike Argon (40) was placed before Potassium (39), Tellurium (127.5) was placed before iodine (127)

Q. Give the salient features of Mendeleev’s periodic table.

SALIENT FEATURES OF MENDELEEV’S TABLE

1. It has vertical columns called groups.

2. It has twelve horizontal rows called periods.

3. Elements in each group have similar properties.

4. Vacant spaces were left for the un-discovered elements.

Q. State Modern periodic table.

MODERN PERIODIC TABLE

STATEMENT

“The physical and chemical properties of the elements are the periodic function of their increasing atomic numbers.”

Q. Define Periodicity, Groups and Periods.

PERIODICITY

The repetition or recurrence of similar chemical properties having elements after a small interval is called periodicity.

GROUPS

The horizontal rows in the periodic table are called groups.

There are eight groups in the modern Periodic Table.

Group number indicates the valence electrons. So, elements which share similar chemical properties are placed in similar group.

PERIODS

The vertical columns in the periodic table are called periods.

In the Modern periodic table, there are seven periods.

Q. Name the elements of Group IA. Also write their general characteristics.

GROUP IA

The elements of group IA are called alkali metals. Group IA is called Lithium family.

ELEMENTS

· Lithium [Li]

· Sodium [Na]

· Potassium [K]

· Rubidium [Ra]

· Caesium [Cs]

· Francium [Fr]

GENERAL CHARACTEISITICS

1. They are highly reactive metals.

2. They are electropositive in nature

3. They have low melting point.

II A

4. Their valence shell contains one electron.

5. They form ionic compounds.

6. Reactivity increases in group from top to bottom

Q. Name the elements of Group IIA. Also write their general characteristics.

GROUP IIA

Elements of Group IIA are called Alkaline earth metals. Group IIA is also called Beryllium family.

ELEMENTS

· Beryllium [Be]

· Magnesium [Mg]

· Calcium [Ca]

· Strontium [Sr]

· Barium [Ba]

· Radium [Ra]

GENERAL CHARACTERISTICS

1. There valence shell contains two electrons.

2. They are metals.

3. They have high melting point and boiling point.

IIIA

4. They have smaller atomic radii and atomic volume.

5. They are divalent electropositive elements.

6. Reactivity increases down the group.

Q. Name the elements of Group IIIA. Also write their general characteristics.

GROUP IIIA

Group IIIA is also called Boron family.

ELEMENTS

· Boron [B]

· Aluminium [Al]

· Gallium [Ga]

· Indium [In]

· Thallium [Tl]

GENERAL CHARACTERISTICS

1. There valence shell contains three electrons.

2. They are highly electropositive elements.

3. They possess metallic characters.

4. Only boron is metalloid.

5. Reactivity increases down the group.

IVA

Q. Name the elements of Group IVA. Also write their general characteristics.

GROUP IV A

Group IVA is also called Carbon family.

ELEMENTS

· Carbon [C]

· Silicon

· Germanium [Ge]

· Tin [Sn]

· Lead [Pb]

GENERAL CHARACTERISITCS

1. It includes metals, nonmetals and metalloid.

2. They have different allotropic forms.

3. They form covalent compounds.

4. Their valence shell contains four electrons.

5. They contain four electron in valence shell

6. They show nonmetallic characteristics.

Q. Name the elements of Group VA. Also write their general characteristics.

GROUP VA

Group VA is also called Nitrogen family.

ELEMENTS

· Nitrogen [N]

· Phosphorous [P]

· Arsenic [As]

· Anitimony [Sb]

· Bismuth [Bi]

GENERAL CHARACTERISTICS

1. There valence shell contains five electrons.

2. They are nonmetals, metal and metalloid.

3. Nitrogen exists in diatomic state while phosphorous exists in tetra atomic form.

4. Except nitrogen, all exists in more than one allotropic form.

5. They are trivalent electronegative elements.

6. They have ionization potential and high electro negativity.

Q. Name the elements of Group VIA. Also write their general characteristics.

GROUP VI A

VIA

Group VIA is also called Oxygen family.

ELEMENTS

· Oxygen [O]

· Sulphur [S]

· Selenium [Se]

· Tellurium [Te]

· Polonium [Po]

GENERAL CHRACTERISTICS

1. They exhibit the property of allotropy.

2. They possess six electrons in their valence shell.

3. They are nonmetal, and metals.

4. They require only two electrons to complete their valence shell.

5. They have high ionization potential high electro negativity.

6. They form ionic compounds when react with metals but form covalent compounds when react with nonmetals.

Q. Name the elements of Group VIIA. Also write their general characteristics.

VII A

GROUP VII A

Group VIIA is also called Fluorine family. Elements of group VII A is also called Halogens or Salt formers.

ELEMENTS

· Fluorine [F]

· Chlorine [Cl]

· Bromine [Br]

· Iodine [I]

· Astatine [At]

GENERAL CHARACTERISTICS

1. They are non-metals

2. They have electronegative charge

3. They have high melting point

4. Their valence shell contains seven electrons.

5. They form ionic compounds when react with metals but form covalent compounds when react with nonmetals.

6. They found as diatomic molecule.

VIII A

Q. Name the elements of Group VIIIA. Also write their general characteristics.

GROUP VIIIA

ELEMENTS

Helium [[He]

· Neon [Ne]

· Argon [Ar]

· Krypton {Kr]

· Xenon [Xe]

· Radon {Rn}

GENERAL CHARACTERISTICS

1. They have eight electrons in there valence shell.

2. They do not take part in chemical reaction.

3. They are nonmetals.

4. They are also known as invert gases.

5. They are mono atomic gases.

6. They are highly stable elements.

Q. Name the elements of Transition elements. Also write their general characteristics.

TRANSITION ELEMENTS

ELEMENTS

· Scandium [Sc]

· Titanium [Ti]

· Vanadium [V]

· Chromium [Cr]

· Manganese [Mn]

· Iron [Fe]

· Cobalt [Co]

· Nickel [Ni]

· Copper [Cu]

· Zinc [Zn]

CHARACTERISTICS

1. They are metals

2. They show variable valence

3. They forms color compounds.

4. They have magnetic and catalytic properties.

5. They have incomplete penultimate shell or valence shell.

Q. Briefly describe Periods of Modern periodic table.

PERIODS

1^ST PERIOD

It is shortest period which consists of only hydrogen (H) and Helium (He).

2^ND AND 3^RD PERIOD:

2^nd and 3^rd periods are called short periods. There are total 8 elements in each period.

The elements of 2^nd period are:

The elements of 3^rd period are:

4^TH PERIOD:

It is called long period. It includes total 18 elements out of which 8 are normal while 10 are transition elements.

Normal elements are:

Transition elements are:

5^TH PERIOD:

It is also called long period. It contains 8 normal and 10 transition elements.

Normal elements are:

Transition elements are:

6^TH PERIOD:

It is the longest period. It consists of 32 elements out of which 8 are normal, 10 are transition and 14 are inner transition elements (Lanthanide or Rare elements).

Normal elements are:

Transition elements are:

Inner transition elements are:

Ce	Pr	Nd	Pm	Sm	Eu	Gd	Tb	Dy	Ho
Ex	Tm	Yb	Lu

7^TH PERIOD:

It is the incomplete period. It contains 2 normal elements, 14 inner transition elements called Actinide elements and 8 are outer transition elements.

Q. Write few lines about Lanthanide and Actinide series.

LANTHANIDE AND ACTINIDE SERIES

The lanthanide and actinide series form the inner transition metals. The lanthanide series includes elements having atomic number from 58 to 71, which fill their 4f sublevel progressively while the actinides are elements having atomic number 89 to 103 and fill their 5f sublevel progressively.

The elements of this series are radioactive in nature and have some special characteristics with exception of the other groups.

Q. Write few lines about Metals.

METAL

Those elements which have tendency or ability to easily donate their valence electrons are called Metals.

1. These elements readily lose their valence electrons

2. They form basic oxides.

3. They are also called reducing agents.

4. They form cations.

5. They have shiny surface.

6. They are malleable and ductile.

7. They are electropositive elements.

Q. Write few lines about Non-Metals.

NONMETAL

Those elements which have ability or tendency to easily accept their valence electrons are called nonmetals.

1. These elements do not lose their valence electrons.

2. They form acidic oxides.

3. They form anions.

4. They have high values of electro negativities.

5. They are electronegative elements.

6. They are brittle.

Q. Write few lines about Metalloid.

METALLOID

Those elements which have dual character as metals and nonmetals are called metalloid.

1. Metalloids have a solid state of matter.

2. In general, metalloids have a metallic luster.

3. Metalloids have low elasticity, they are very brittle.

4. Middleweights are semi-conducted elements, and they allow leave the average transmission of heat.

Q. Define atomic radius. Also discuss its group trend.

ATOMIC RADIUS

The half distance between two adjacent nuclei of two similar atoms is called atomic radius.

UNIT:

It is measured in Angstrom (A^o)

1A^o = 10^-10 m OR 1A^o = 10^-8 cm

GROUP TREND

Atomic radii increases down the group due to increase in number of shell and decrease along the period due to increase in number of protons.

DOWN THE GROUP

Beryllium = 1.12

Magnesium = 1.36

Calcium = 1.97

ALONG THE PERIOD

Sodium = 1.51

Magnesium = 1.36

Aluminium = 1.25

Q. Define electronegativity. Also discuss its group trend.

ELECTRO-NEGATIVITY

The amount of energy required to attract the shared pair of electron is called electro-negativity.

GROUP TREND

It decreases down the group as the power of the nucleus decreases for the attraction of electrons and it increases along the period due to increase in nuclear charge.

DOWN THE GROUP

Fluorine = 4.0

Chlorine = 3.0

Bromine = 2.8

ALONG THE PERIOD

Boron = 2.0

Carbon = 2.5

Nitrogen = 3.1

Q. Define electron affinity. Also discuss its group trend.

ELECTRON AFFINITY

The energy accompanied the gain of electron by a neutral gaseous atom to form a negative ion is called electron affinity.

GROUP TREND

In the period the electron affinity increases due to higher atomic charge on atoms which attracts the incoming electrons toward their self. On the other hand, it decreases down the group because of the addition of new shells.

DOWN THE GROUP

Fluorine = -333

Chlorine = -348

Bromine = -324

ALONG THE PERIOD

Lithium = -58

Beryllium = 0

Boron = -23

Q. Define ionization potential. Also discuss its group trend.

IONIZATION POTENTIAL

The energy required to remove the electron from a gaseous atom in its ground state is called ionization potential.

GROUP TREND

Down the group the ionization potential decreases due to the addition of shell while it increases in the period because addition of protons increase the nuclear charge there by increasing the force of attractions .

ALONG THE PERIOD

Boron = 8.29

Carbon = 11.26

Nitrogen = 14.54

DOWN THE GROUP

Boron =8.29

Aluminium = 5.98

Gallium = 6.0

Chemistry 9th & 10th Class

Chemistry 9th Class

Friday, January 15, 2021

Chapter # 04 [Arrangement of Elements]

UNIT# 04

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