Periodic Table - Engineers' Class file6/7/2013 · Elements in a Periodic Table •Periodic Properties and Periodic Trends. Engr. Yvonne Ligaya F. Musico 3 What is Periodic Table?

Engr. Yvonne Ligaya F. Musico 1

Periodic Table


TOPIC

• Definition of Periodic Table

• Historical Development of the Periodic Table

• The Periodic Law and Organization of

Elements in a Periodic Table

• Periodic Properties and Periodic Trends


What is Periodic Table?

Periodic Table

• A table of elements written in the order of

increasing atomic number and arranged in

horizontal rows (periods) and vertical columns

(groups) to show similarities in the properties

between elements.



Historical Development of

Periodic Table


Johann Wolfgang Dobereiner

(1780 – 1849)

• He grouped similar elements with almost equal

atomic weights into groups of three or

TRIADS

Example:

(Br, I, Cl)

(Sr, Ca, Ba)

(Se, S, Te)


John A. Newlands

(1838 – 1898)

• He grouped all elements in the order of their

atomic weights.

• He then divided the elements into groups of

seven elements (noble gases were unknown at

that time)


Lothar Meyer

(1830 – 1895)

• He plotted a graph showing an attempt to

group elements according to atomic weights


Dmitri Mendeleev

(1834 – 1907)

• He arranged elements in the order of

increasing atomic weights.

• In this table, the first two periods had seven

elements each. The next periods contained

seventeen elements each.


Dmitri Mendeleev

(1834 – 1907)

• The discovery of the inert gas during the 1890’s added and additional element to each period.

• He left spaces for elements that might someday be discovered.

• He studied the properties of the elements and predicted the properties would be discovered elements.


Henry Moseley

(1877 - 1915)

• He used X-rays to determine the atomic number (proton) of the elements.

• X-rays are light radiation with high frequency and a short wave length.

• The higher the atomic number of the elements the shorter the wavelength of X-rays will be when the element is used as a target.


Henry Moseley

(1877 - 1915)

• Resolved discrepancies in Mendeleev’s

arrangement

• He concluded that the elements should be

arranged in the order of increasing atomic

number


Periodic Law and Organization of

Elements in a Periodic Table


Periodic Law

• This law states that some of the physical and

many chemical properties of the elements are

periodic functions of their atomic numbers.


The Periodic Table

• The Modern Periodic Table

– Elements listed in order of increasing atomic

number


The Periodic Table

• Group or Families

– a vertical column of elements

– contains elements with similar chemical properties

– these groups are divided into A and B subgroups.

– the group number in the A subgroup shows this number of

valence electron

Example:

Phosphorus belong to VA so its valence e- is 5


The Periodic Table

• Periods

– a horizontal row of elements

– designated by numbers 1-7 on the side of the periodic table

– elements are not related chemically

– the period number denotes the number of main energy level (shell) of the atom.

Example:

Sodium is in period 3 so its atom is composed of 3

shells and its outermost shell is the 3rd shell


The Periodic Table


The Periodic Table

• Metals

– Mostly solid except Hg which is liquid at room at

temperature

– Good electrical and thermal conductivity

– High density, high melting point and boiling point


The Periodic Table

• Metals

– Combine with non-metals to produce salts

– Do not combine with each other

– To the left of the stairstep line that in general

separates the metal and non-metals


The Periodic Table

• Metals

Example:

Na, Cu, Fe, Au, Pb


The Periodic Table

• MetalsStairstep line separating metals

from non metal


The Periodic Table

• Non Metals

– Several exist as gases at room temperature

– Poor electrical and thermal conductivity

– Low density, low melting point and boiling point


The Periodic Table

• Non Metals

– Combine with metals to produce salts

– Some combine with each other

– To the right of the of the dark stairstep line that

separates the metals from non metals


The Periodic Table

• Non Metals

Example:

C, N, O, S, Cl, He


The Periodic Table

• Non -Metals Stairstep line separating metals

from non metal


The Periodic Table

• Metalloids

– properties intermediate between those of

metals and nonmetals

Examples:

B, Al, Si, Sb, Sn, Po


Group or Families in Periodic Table

• Alkali metals – Group IA

• Alkaline Earth Metals – Group IIA

• Halogens – Group VIIA

• Boron Family – IIIA

• Carbon Family – IVA

• Nitrogen Family – VA

• Oxygen Family – VIA

• Noble Gases – VIIIA

• Group 0 – very stable configuration with 8 e- in the outermost shell except He.


The Periodic Table of the Elements


Blocks in Periodic Table

• Representative

Elements

• Noble Gases

• Transition Elements

• Inner Transition

Elements


Representative Elements

• The A subgroups IA through VIIA

• These elements, the outer energy level is

incomplete and the electrons are occupying s or p

orbitals.

• The electron configuration will be from ns1 to np5

(n is the period number)


Representative Elements

Example

a) Sodium (Na) at no. = 11, being 3 and & Group IA.

So Na would have one e- in the 3s orbital,

configuration in 3s1 with all lower orbitals being

completely filled.

b) Nitrogen (N) at no. 7, in the period 2 & in Group VA.

So N would have 2e- in the 2s orbitals and 3e- in the

2p3 with all lower orbital completely filled.


Noble Gases

• Each elements in this group has a completely filled

set of s and p orbitals.

• The electron configuration for the outermost e- is

ns2, np6 (except He, ns2). This is very stable

configuration.


Noble Gases

Example

Krypton (Kr), period 4, group VIIIA

Configuration is 4s2, 4p6 in the outermost energy

level.


Transition Elements

• The series having a set of incomplete d orbitals.

• These elements are the B subgroups.

• In general, the outermost energy level here will have an ns2

configuration [except VIB and IB (ns1)].

• The outermost electron added to the electrons in the inner

incomplete d orbital corresponds to the group number in the

B subgroups (maximum is 8)


Transition Elements

Example

a) Iron (Fe)

- Period 4, group VIIIB

- Period 4, the last energy level is the 4th

- Group VIIIB, it has an inner incomplete d orbital in the 3rd

energy level (this d orbital are of one energy level lower).

b) In case of Chromium (Cr) group VIB, the configuration is 4s1, 3d5.

c) For copper (Cu) group IB, the configuration is 4s1, 3d10


Inner Transition Elements

• Two series of elements

– from 58 to 71 called the Lathanide series and belongs to period 6

– from 90 to 110 called Actinide series series and belongs to period 7

• In general, these elements have three incomplete energy levels since one electron enters an orbital before the set of orbitals begin filling


Inner Transition Elements

There are many exceptions to the order of filling of orbitals going across. Consider the following examples:

• Chlorine (Cl) is a representative element

• Manganese (Mn) is a transition element

• Magnesium (Mg) is a representative element

• Argon (Ar) is a noble gas

• Uranium (U) is an inner transition element


Periodic Properties and Periodic

Trends


Periodic Properties and Periodic Trends

• Atomic size

• Ionization Energy

• Electron Affinity

• Electronegativity


Atomic Size

• The size of the atoms become bigger as the number

of shells increases.

• Going down any group in the table there is large

increase in atomic size.

• The increase in the number of energy levels causes

the increase in the atomic radius.


Atomic Size

• Going across any period, there is a small but rather

decrease in size of the atomic radius.

• As the atomic number increases, the nuclear charge

becomes greater.

• Each electron is attracted towards the nucleus

making it closer to the nucleus causing the decrease

in the atomic radius


Atomic Size

1

2

3

4

5

6

7

INCREASES

I

N

C

R

E

A

S

E

S


Atomic Size

Example

Using the periodic table, arrange the following elements in order of decreasing atomic size: Br, Sr, Sn, I, Cs, Ba.

Solution:

Going down the group and across the period the order is Cs, Ba, Sr, Sn, I, Br


Atomic Size


Ionization Energy

• The amount of energy required to remove an

electron from an atom.

• Going down the group in the table, the ionization

energy decreases from one atom to the next.

• Going across a period, there is a general increase of

ionization energy.


Ionization Energy

1

2

3

4

5

6

7

INCREASES

I

N

C

R

E

A

S

E

S


Ionization Energy

Example:

Choose the one with the highest ionization energy: Na, Al, Cl, Br

Solution:

Cl – since this has the smallest atomic size (that is the valence electron is closer to the nucleus) ionization energy is highest.


Electron Affinity

• The amount of energy released when an electron is

added to an atom.

• Going down a group of non-metals such as halogen

(Group VIIA) the electron affinity decreases.

• Going across the period such as from nitrogen to

oxygen to flourine, the electron affinity increases.


Electron Affinity

1

2

3

4

5

6

7

INCREASES

I

N

C

R

E

A

S

E

S


Electronegativity

• It is defined as the tendency of that atom to attract

electrons toward itself

• Going down a group electronegativity decreases

• Going down across the period electronegativity

increases


Electronegativity

• Low electronegativity is characteristic of metals

• The lower electronegativity are found at the lower left of the

Periodic Table.

• High electronegativity is a characteristic of non-metals.

• Fluorine is the most electronegative element. Oxygen is the

second.

• The electronegativity ranges 2.2 to 4.0


Electronegativity

1

2

3

4

5

6

7

INCREASES

I

N

C

R

E

A

S

E

S


Electronegativity

Example:

Arrange the following elements in order of increasing electronegativity: Ba, Br, I, Sn, Sr

Solution:

Looking at position in the periodic table including the group and period, gives the following order.

Ba, Sr, Sn, I, Br

Electronegativity ranges between 1.8 & 2.1

ENGR. YVONNE LIGAYA F. MUSICO

Periodic Table - Engineers' Class file6/7/2013 · Elements in a Periodic Table •Periodic Properties and Periodic Trends. Engr. Yvonne Ligaya F. Musico 3 What is Periodic Table?

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