what is periodic table

8/2/2019 What is Periodic Table

1/19

PROJECT OF CHEMISTRYTHE PERIODIC TABLE

4/11/2012

ALI AKBAR

TO MISS AMNA


2/19

Table of Contents

What is periodic table? ......................................................................3

History of Periodic table .....................................................................4

Mendeleevs Periodic Table ...............................................................5

Modern Periodic Table .......................................................................7

Groups ...............................................................................................9

Periods ..............................................................................................9

General Features of Periodic Table ................................................... 10

Classification of General Properties .................................................. 10Metalloids. ...................................................................................... 10

METALS ........................................................................................... 10

Alkali Metals .................................................................................... 11

Alkaline Earth Metals ....................................................................... 11

Non metals ...................................................................................... 12

The Halogens ................................................................................... 12

Transition metals ............................................................................. 13

The noble or inert gases ................................................................... 13

Salient features of Periodic table ...................................................... 15

How elements are placed in periodic table? ..................................... 16

Reference ........................................................................................ 19


3/19

What is periodic table?

The periodic table is a tabular display of the chemical elements,

organized on the basis of their properties. Elements are presented in

increasing atomic number. While rectangular in general outline, gapsare included in the rows or periods to keep elements with similar

properties together, such as the halogens and the noble gases, in

columns or groups, forming distinct rectangular areas or blocks.
http://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Period_(periodic_table)http://en.wikipedia.org/wiki/Halogenhttp://en.wikipedia.org/wiki/Noble_gashttp://en.wikipedia.org/wiki/Group_(periodic_table)http://en.wikipedia.org/wiki/Block_(periodic_table)http://en.wikipedia.org/wiki/Block_(periodic_table)http://en.wikipedia.org/wiki/Group_(periodic_table)http://en.wikipedia.org/wiki/Noble_gashttp://en.wikipedia.org/wiki/Halogenhttp://en.wikipedia.org/wiki/Period_(periodic_table)http://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Chemical_element


4/19

History of Periodic table

The history of the periodic table reflects over a century of growth in

the understanding of chemical properties, and culminates with the

publication of the first actual periodic table by Dmitri Mendeleev in

1869.While Mendeleev built upon earlier discoveries by such scientists

such as AL-RAZIN and MANDALEEVE.

The table itself is a visual representation of the periodic law which

states that certain properties ofelements repeatperiodicallywhen

arranged by atomic number. The table arranges elements into vertical

columns (groups) and horizontal rows (periods) to display these

commonalities.
http://en.wikipedia.org/wiki/Periodic_tablehttp://en.wikipedia.org/wiki/Dmitri_Mendeleevhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Dmitri_Mendeleevhttp://en.wikipedia.org/wiki/Periodic_table


5/19

Mendeleevs Periodic Table

Dmitri Mendeleev was a Russian chemist and inventor. He is credited as

being the creator of the first version of the periodic table ofelements.Using the table, he predicted the properties of elements yet to be

discovered.Mendeleev realized that the physical and chemical

properties of elements were related to their atomic mass in a 'periodic'

way, and arranged them so that groups of elements with similar

properties fell into vertical columns in his table.

Gaps and predictions Sometimes this method of arranging elementsmeant there were gaps in his horizontal rows or 'periods'. But instead

of seeing this as a problem, Mendeleev thought it simply meant that

the elements which belonged in the gaps had not yet been discovered.

He was also able to work out the atomic mass of the missing elements,

and so predict their properties. And when they were discovered,

Mendeleev turned out to be right. For example, he predicted the

properties of an undiscovered element that should fit below aluminumin his table. When this element, called gallium, was discovered

in 1875 its properties were found to be close

to Mendeleev's predictions. Two other predicted elements were later

discovered, lending further credit to Mendeleev's table.
http://en.wikipedia.org/wiki/Chemistryhttp://en.wikipedia.org/wiki/Periodic_tablehttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Periodic_tablehttp://en.wikipedia.org/wiki/Chemistry


6/19


7/19

Modern Periodic Table

Our modern day periodic table is expanded beyond Mendeleev's initial

63 elements. Most of the current periodic tables include 108 or 109

elements. It is also important to notice how the modern periodic tableis arranged. Although we have retained the format of rows and

columns, which reflects a natural order, the rows of today's tables show

elements in the order of Mendeleev's columns. In other words the

elements of what we now call a "period" were listed vertically by

Mendeleev. Chemical "groups" are now shown vertically in contrast to

their horizontal format in Mendeleev's table. Note also that

Mendeleev's 1871 arrangement was related to the atomic ratios in

which elements formed oxides, binary compounds with oxygen;

whereas today's periodic tables are arranged by increasing atomic

numbers, that is, the number of protons a particular element contains.

Although we can imply the formulas for oxides from today's periodic

table, it is not explicitly stated as it was in Mendeleev's 1871 table. The

oxides ratio column was not shown in earlier Mendeleev versions.


8/19


9/19

Groups

Group is a vertical column of elements in the periodic table with the

same number of valence electrons.

The modern periodic table of the elements contains 18 groups, or

vertical columns. Elements in a group have similar chemical and

physical properties because they have the same number of outer

electrons. Elements in a group are like members of a family--each is

different, but all are related by common characteristic

Periods

Period is the horizontal row of elements in the periodic table. Table

with the period number including the numbers of valence electron

shells. Along a period, a gradual change in chemical properties occurs

from one element to another. For example, metallic properties

decrease and nonmetallic properties increase as you go from left to

right across a period. Changes in the properties occur because the

number of protons and electron increases from left to right across aperiod or row. The increase in number of electrons is important

because the outer electrons determine the element's chemical

properties.


10/19

General Features of Periodic Table

Classification of General Properties

The general properties of elements allow them to be divided into threeclassifications: metals, nonmetals and

Metalloids

The distribution of metals is shown in your periodic table as boxes

colored yellow, purple and two shades of blue. Metalloid elements are

in the diagonal boxes colored pink and nonmetal elements are above

the diagonal line to the right of the metalloids, in boxes colored green,gold, and red. Notice that hydrogen's box is colored green, even

though it is at the top of a group of metals.

METALS

As you can see, the vast majority of the known elements are metals.

Many metals are easily recognized by non-chemists. Common

examples are copper, lead, silver and gold. In general, metals have a

luster, are quite dense, and are good conductors of heat and electricity.

They tend to be soft, malleable and ductile (meaning that they are

easily shaped and can be drawn into fine wires without breaking). All of

these properties are directly related to the fact that solid metals are

crystals formed from positive ions surrounded by mobile electrons.

This mobility allows electrons to absorb and reflect light in many

wavelengths, giving the metals their typical luster The Group I Alkali

Metals and the Group II Alkaline Earths have more metallic

characteristics than elements farther right whose square are colored

blue.


11/19

Alkali Metals

The alkali (IA) metals show a closer relationship in their properties than

do any other family of elements in the periodic table. Alkali metals are

so chemically reactive that they are never found in the element form innature. All these metals react spontaneously with gases in the air, so

they must be kept immersed in oil in the storeroom. They are so soft

that they can be cut with an ordinary table knife, revealing a very

"buttery", silvery metal surface that immediately turns dull as it reacts

with water vapor and oxygen in the air. The chemical reactivity of alkali

metals increases as the atomic number increases.

Alkaline Earth Metals

The alkaline earth (IIA) metals also exhibit the typical metal

characteristics of high density, metallic luster and electrical and thermal

conductivity. Rocks and minerals containing silica, magnesium, and

calcium compounds are widely distributed. These chemicals are also

abundant as compounds in sea water. Their chlorides are abundant in

sea water. Radium, the largest of the alkaline earths, is a radio active

element that occurs naturally only in very small quantities. Chlorophyll,

the green coloring in plants, is a magnesium-containing compound.

Calcium is a major component of animal bones, teeth and nerve cells.

Alkaline earth elements form compounds by losing, or in the case of

beryllium, sharing two electrons per atom. These atoms hold their

electrons more tightly than alkali metals. They are, therefore, smaller

than and not so chemically reactive as the neighboring alkali metals.


12/19

Non metals

Nonmetal, or non-metal, is a term used in chemistry when classifying

the chemical elements. On the basis of their general physical and

chemical properties.

There is no rigorous definition for the term "nonmetal" - it covers

a general spectrum of behavior. Common properties considered

characteristic of a nonmetal include:

poor conductors of heat and electricity when compared to metals

they form acidic oxides (whereas metals generally form basic

oxides) in solid form, they are dull and brittle, rather than metals which

are lustrous, ductile or malleable

usually have lower densities than metals

they have significantly lower melting points and boiling points

than metals (with the exception of carbon)

Non-metals have high electro negativity.

The Halogens

The halogens or halogen elements are a series of nonmetal elements

from Group 17 IUPAC Style (formerly: VII, VIIA) of the periodic table,

comprising fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and

astatine (At). The artificially created element 117, provisionally referred

to by the systematic name ununseptium, may also be a halogen.The

group of halogens is the only periodic table group which contains

elements in all three familiar states of matter at standard temperature

and pressure.


13/19

Transition metals

The transition elements are also known as the transition metals. These

elements are very hard, with high melting points and boiling points.

Moving from left to right across the periodic table, the five d orbitalsbecome more filled. The d electrons are loosely bound, which

contributes to the high electrical conductivity and malleability of the

transition elements. The transition elements have low ionization

energies. They exhibit a wide range of oxidation states or positively

charged forms. The positive oxidation states allow transition elements

to form many different ionic and partially ionic compounds.

The noble or inert gases

The noble gases are a group of chemical elements with very similar

properties: under standard conditions, they are all odorless, colorless,

monatomic gases, with very low chemical reactivity. The six noble gases

that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr),

xenon (Xe), and the radioactive radon (Rn). The properties of the noble

gases can be well explained by modern theories of atomic structure:

their outer shell of valence electrons is considered to be "full", giving

them little tendency to participate in chemical reactions, and it has only

been possible to prepare a few hundred noble gas compounds. The

melting and boiling points for each noble gas are close together,

differing by less than 10 C (18 F); consequently, they are liquids over

only a small temperature range.


14/19


15/19

Salient features of Periodic table

The grouping of elements with similar properties together and the

separation of elements with dissimilar properties is known as

classification of elements. The table, which classifies elements onthe basis of their properties, is called the periodic table.

The earliest classification was into metals and non-metals, which

was on the basis of physical and chemical properties.

According to Mendeleev's periodic law, the physical and chemical

properties of elements are periodic functions of their atomic mass

Mendeleev was able to predict the existence of undiscovered

elements

Mendeleev corrected the atomic masses of a few elements on the

basis of their positions in the periodic table

Mendeleev's table could not assign a proper position to hydrogen

or to the lanthanides and actinides and isotopes

Modern periodic law states that the properties of elements are

periodic functions of their atomic numbers. It is based on

electronic configuration of the elements

The vertical columns are called groups, while the horizontal rows

are called periods

There are 7 periods and 8 groups subdivided into 18 sub groups

Group number is number of electrons in the valence shell.

Elements having the same valence number are grouped together. The number of shells present in the atom gives period number


16/19

How elements are placed in periodic table?

As stated last section, the periodic table organizes the elements

according to general patterns of similarity. Below is a very small image

of the periodic table. It is basically unreadable in terms of specificinformation, but it allows us to easily look at the periodic tables

structure general trends. The vertical columns of the periodic table

(marked by yellow stripes in the figure) are called groups. The

horizontal rows are called periods. There are 18 groups and 7 periods.

In discussing the periodic table from here on out we will use the terms

group and period. Down a group means moving from top to bottom;

across a period means moving from left to right.

Reading the Periodic Table: Carbon

To describe the information contained within each individual box we

will use a specific example: carbon.

Figure %: Description of Carbon on the Periodic Table


17/19

Element Name

The purpose of the element name is obvious. However, many Periodic

Tables do not include element names. For those situations you must

memorize the symbols that accord to each element name.

Element Symbol

Each element has a specific one or two letter symbol that is used

interchangeably with its name. These should be memorized. Most of

the time, symbols quite clearly accord to the name of the element they

represent, as C accords to carbon. Occasional, however, an element's

name and symbol have little relation. For example, the symbol for

mercury is Hg.

As you move across a period the atomic number increases. Similarly, as

you move down a group the atomic number increases. In this way, the

atomic number represents exactly where in the periodic table an

element stands.

More importantly, and the reason why the ordering of the elements

according to atomic number yields elements in groups with similar

chemical and physical properties, the atomic number is the same as the

number of protons in the nucleus of an atom of an element, and also

the same as the number of electrons surrounding the nucleus in a

neutral state. Carbon, for example, has six protons and six electrons.


18/19

Atomic Mass

Along with protons, an atom also contains neutrons in its nucleus. The

atomic mass (also called atomic weight) of an element is the combined

number of protons and neutrons in the nucleus.

Atoms of particular elements generally have different "versions,"

meaning that elements have atoms with different numbers of neutrons

in their nucleus. These different versions are called isotopes. The

atomic weight displayed is actually the weighted average of the mass

numbers of the various isotopes. The atomic weight for Carbon is 12.01

because around 99% of all carbon is the carbon-12 isotope.

Simple Periodic Trends

Atomic Number

The Atomic number increases from the top left to the bottom right. It

ascends sequentially across each period.

Atomic Weight

Weight The atomic weight of the elements generally increases as you

move down a group and across a period. Hydrogen, at the top left of

the table, is the lightest element. The unnamed element 112 is the

heaviest. There are some instances when this rule does not hold true,

however. For instance, because it has a high percentage of isotopes

with many neutrons, the atomic weight of tellurium (Te) is higher than

that for iodine (I), even though iodine has a higher atomic number.


19/19

Reference

http://www.sparknotes.com/chemistry/fundamentals/period

ictable/section2.rhtml

www.chemicool.com/

http://en.wikipedia.org/wiki/Periodic_table

http://www.lenntech.com/periodic/history/history-periodic-

table.htm
http://www.sparknotes.com/chemistry/fundamentals/periodictable/section2.rhtmlhttp://www.sparknotes.com/chemistry/fundamentals/periodictable/section2.rhtmlhttp://www.chemicool.com/http://en.wikipedia.org/wiki/Periodic_tablehttp://www.lenntech.com/periodic/history/history-periodic-table.htmhttp://www.lenntech.com/periodic/history/history-periodic-table.htmhttp://www.lenntech.com/periodic/history/history-periodic-table.htmhttp://www.lenntech.com/periodic/history/history-periodic-table.htmhttp://en.wikipedia.org/wiki/Periodic_tablehttp://www.chemicool.com/http://www.sparknotes.com/chemistry/fundamentals/periodictable/section2.rhtmlhttp://www.sparknotes.com/chemistry/fundamentals/periodictable/section2.rhtml

what is periodic table

Documents