PERIODICITY"THERE ARE ONLY TWO WAYS TO LIVE YOUR LIFE. ONE IS AS

THOUGH NOTHING IS A MIRACLE. THE OTHER IS AS THOUGH EVERYTHING IS." -- ALBERT EINSTEIN

Ch.6 J.C. Rowe

Windsor University School of Medicine

Modern Periodic Table

What is the Periodic Table? An arrangement of the chemical elements in which the

elements are arranged by order of atomic number in such a way that the periodic properties (chemical periodicity) of the elements are made clear.

The standard form of the table includes periods (usually horizontal in the periodic table) and groups (usually vertical). Elements in groups have some similar properties to each other.

The periodic table is a masterpiece of organized chemical information. The evolution of chemistry's periodic table into the current form is an astonishing achievement with major contributions from many famous chemists and other eminent scientists

What is the Periodic Table? Cont’d there are a number of ways that the elements

have been arranged--we will use the "Modern Periodic Table" which is derived from Mendeleev's version of the organization of the elements. Modern Periodic Table is based upon increasing atomic

number of the elements and allows for organization of the elements as well as grouping of the elements according to chemical and physical properties Groups – are the vertical groupings or columns of elements in

the table Periods – are the horizontal groupings or rows of elements in

the table

The Mendeleev Periodic Table

Groups & Periods The vertical columns

in the Periodic Table are called GROUPS.

Groups are numbered with Roman numbers (I, II, III….)

The horizontal rows are called PERIODS.

Periods are numbered with ordinary numbers.

groups

periods

Three major groupings of types of elements

Metals -- generally hard, shiny, dense, conductive with a shiny luster examples would be copper, lead, sodium know which elements on the periodic table are metals -- in the

periodic table in the front of your eyes, metals are in yellow Non-metals -- do not exhibit the properties of metals,

they are generally insulators, brittle, and often gaseous examples would be chlorine, neon, sulfur know which elements on the periodic table are non-metals -- in

front of your eyes, non-metals are green Metalloids – have properties in between those of metals

and non-metals -- in front…..., metalloids are purple they are boron, silicon, germanium, arsenic, antimony,

tellurium, astatine, know these

What is the Periodic Table?

Periodic Trends Elements that border

on the amphoteric line are Metalloids (dark gray). They have characteristics of both.

Metals (blue)

Nonmetals (light gray)

There are assorted named sub-groupings

There are assorted named sub-groupings which you should be familiar with: Representative elements -- all Group A elements Transition elements – all Group B elements

Group #                     Name                     IA                            alkali metals      IIA                           alkaline earth metals      VA                           nitrogen group      VIA                          oxygen group or chalcogens      VIIA                         halogens      VIIIA                        nobel gases

Group A vs. Group B

Atomic Number(Z) vs. Mass number (A)

two numbers on the periodic table which you must become very familiar with are: the atomic number--it

is the smaller number and is always a whole number

the mass number--it is the larger number and is a decimal number

Atomic #

Mass #

Characteristics

1. Have lusters2. Are malleables &

ductille3. Conduct heat &

electricity4. Tend to lose

electrons

1. Are dull2. Are brittle3. Do not conduct

heat or electricity very well

4. Tend to gain electrons

MetalsNonmetals

Stable electronic configurations

Metals tend to lose their outershell electrons in order to be stable.

Stable positively charged ions (cations)

The ability to lose electrons makes them good reducing agents.

Non-metals tend to easily gain electrons in order to be stable.

Stable negatively charged ions (anions)

The ability to gain electrons makes them good oxidising agents

Metals / cations Non- metals/ anions

Ionic states :Cation or Anion

LOSS of electron leads to CATION (+)

GAIN of electron leads to ANION (-)

How Elements React When an element reacts with another

element, the outershell of elements of each atom is what first comes into contact with the other atoms.

When elements react, they are usually either :1. Transferring electrons from their outershells

to another element2. Transferring electrons to their outershells

from another element3. Sharing electrons in their outershells with

another element.

How Elements React Cont’d. Often atoms react with other atoms in

order to achieve an octet ( 8 electrons in their outer shell), so the number of electron in their outer shell determines how many electrons they need to gain or lose to achieve an octet.

So it is the number of electrons in the outer shell that is most important in determining how an element will react with another elements.

Valence Electrons

Valence electrons Cont’d. Within a group, elements have very similar

valence electron configurations--same number of electrons in the same type of subshells but the only difference is in the major shell. 

The electron configurations of the valence electrons are very important.

the most important electrons in an atom are those on the outer-most edge of the atom (the outer major shell) – they come into contact with other atoms first and participate fully in reactions – they are the valence electrons

valence shells contain the valence electrons

s-p-d-f long form periodic table

s-block Group IA and IIAvalence electrons are in the ns subshell where 'n' denotes the major shell or row

p-block Group IIIA - VIIIAvalence electrons are in the ns and np subshell where 'n' denotes the major shell or row

d-block Group IB - VIIIB (Transition Metals)valence electrons are in the ns and (n-1)d subshell

f-block Inner Transition Metals sometimes called the lanthanides & the actinides valence electrons are in the ns and (n-2)d subshell

The electron configurations of the valence electrons are very important

s-block Group IA and IIAvalence electrons are in the ns subshell where 'n' denotes the major shell or row

p-block Group IIIA - VIIIAvalence electrons are in the ns and np subshell where 'n' denotes the major shell or row

d-block Group IB - VIIIB (Transition Metals)valence electrons are in the ns and (n-1)d subshell

f-block Inner Transition Metals sometimes called the lanthanides & the actinides valence electrons are in the ns and (n-2)d subshell

Family trends

Family

Atomic Size

atoms increase in size as the number of shells increase—in other words, as the valence electrons occupy larger shells the atoms become larger going down a group

atoms decrease in size as electrons are added to the same shell—in other words, the atoms become smaller across the periodic table from left to right, due to the contraction effect as more electrons and protons are added to the same

shell (as you move from atoms on the left to atoms on the right), the attraction between positive and negative increases and the size of the shell is contracted

Atomic Radius

Ionic Size

positive ions are smaller than the atoms from which they are derived the greater the size of the positive charge,

the smaller size of the ion relative to the atom

negative ions are larger than the atoms from which they are derived the greater the size of the negative charge,

the larger the size of the ion relative to the atom

isoelectronic ions

a series of isoelectronic ions (different ions with the same number of electrons) such as those above, are not the same size

Trends of Electron Affinity

Ionization Energy

ionization energy is the energy required to remove an electron in the formation of an ion—the more difficult it is to remove an electron, the greater the ionization energy

smaller atoms have greater ionization energy since the valence electrons are closer to the nucleus and more strongly attracted and, therefore, more difficult to remove

ionization energy increases going up a group and across a row in the periodic table

Ease of Ionisation

Summary

The primary duty of the University to a student is to provide him with such instructors as will make him realize that the responsibility for progress is his own and no one else's.

S.E. Whitnall, 1933