The Periodic Table of Elements

Chemistry f4 : Chapter 4

The Periodic Table
Of

Elements



The Development of The Periodic Table of Elements

Antoine Lavoisier

Classified elements according to certain group such as gases ,
non-metal , metal & metal oxide

Johann W. Dobereiner
The atomic mass of strontium atom , Sr was similar to the
average mass of calcium atom , Ca and barium atom ,BA .These

elements had the same chemical properties

John Newlands
Arranged elements according to their increasing atomic
masses. He arranged seven elements in a row.

Lothar Meyer

Plotted the graph of atomic volume against atomic mass of
elements. He found that the elements at equivalent positions on

the curve of the graph had similar chemical properties

Dmitri Mendeleev

Arranged the elements according to their increasing atomic
masses. Only elements with similar chemical properties were
arranged in the same vertical columns.

Henry Moseley
Studied the frequencies of X-ray release by various elements
and eventually found a relation between the X-ray spectrum

and proton numbers

Arrangement in the Periodic Table of Elements

Number • Increasing number of proton
• Number of valence electron – position in group
Proton Electron Valence of shells
• Number of shell – position in period
Element number number group Group filled Period

with

electron

Lithium, 3 2.1 1 1 2 2

Li

Calcium, 20 2.8.8.2 2 2 4 4

Ca

Aluminium, 13 2.8.3 3 3+10 = 3 3

Al 13

Silicon, 14 2.8.4 4 4+10 = 3 3

Si 14

Nitrogen, 7 2.5 5 5+10 = 2 2 1 / 2 valence group = no. of
electron valence electron
N 15
3 to 8 valence group = no. of
Oxygen, O 8 2.6 6 6+10 = 2 2 electron valence

16 electron + 10

Bromine, 35 2.8.18.7 7 7+10 = 4 4 Element

Br 17

Krypton, 36 2.8.18.8 8 8+10 = 4 4

Kr 18

Elements In Group 18 Uses of Group 18 in
Elements in Daily Life
He Elemen Atomi Meltin Boiling Density
Ne Noble gases are ts c g point point (gcm^-3 HELIUM NEON
Ar chemically Used for
Kr unreactive due to Helium, Radius (C) (C) 0.00017 Used to advertising
Xe valence shell that are He (nm) 0.00080 fill weather
Rn fully filled with 0.050 -270 -269 0.00170 Used in flashlight
Og electrons. Neon, 0.00350 ballons of camera
Noble gases have Ne 0.070 -248 -246 0.00550
achieved Used to fill KRYPTON
a stable duplet or Argon, 0.094 -189 -186 - electronic bulbs
octet Ar
electron arrangement, 0.109 -156 -152 ARGON
causing the atoms of Krypto
noble gases n, Kr 0.103 -122 -108
to not donate , Xenon,
accept nor share - -71 -62
electrons with the Xe
atoms of Radon,
other elements.
Rn

Used for Used to
lighthouse treat cancer

lamps RADON

XENON

Elements in Group 1 Changes in Physical Properties of Elements When Going Down Group 1

Li Element Atomic Melting Boiling
Na Chemical Properties of Group 1 Elements radius point (C) point (C)
(nm)
K
Rb M+ + e¯ Lithium , 0.133 186 1342
Cs
Li

Sodium, 0.186 98 880

Na

Fr Group 1 elements have one electron in the Potassium, 0.203 64 760
violence shell. In a chemical reaction,
K
these atoms donate one electron and form

an ion with the +1 charge Group 1 elements have low melting point and boiling

point if compared to other metals like iron that has a

melting point of 1540 C and boiling point of 276o C

Group 1 elements are soft metals , with low density

and float on the surface of the water

Physical and Chemistry Properties of Other Elements in Gp 1

Reaction of Group 1 Elements with Water , Oxygen and Chlorine Gas

You have studied the properness ion lithium, sodium and potassium.

How about the properties of other atoms such as rubidium, When alkali metals react with water, alkaline
cesium and francium? hydroxide solution
Like other alkali metals, rubidium, cesium and francium

elements are soft metals with shiny surfaces and have low melting and hydrogen gas is formed. For example, reaction
point and boiling point. Rubidium and cesium are metals that are of lithium with
very reactive and burn easily. Rubidium and cesium are usually
combined with other elements. Thus, they are difficult to be water will produce lithium hydroxide and hydrogen
isolated chemically. Francium element is an unstable radioactive gas.

isotope with a short half-life. All three elements are very reactive 2Li(s) + 211,0(1) > 2LIOH(aq) + H,(g)
with water and oxygen. When alkali metals burn in oxygen gas, a white solid

that is metal oxide will be forme

Changes in Reactivity of or example, reaction of lithium with oxygen gas will

Elements Going Down Group 1 produce lithium oxide.

Experiment 4.1 shows the reactivity 4Li(6) + 0,(R) > 2Li,0(6)
of elements increases when going Solid metal oxide will form an alkaline solution when
down Group 1. Why do the
dissolved in water. For example

changes occur? action of lithium oxide with water will produce
Lithium, Li The reactivity of alkali metals in Group 1 lithium hydroxide.
is due to the tendency of an
atom to donate its valence electrons .The number of shells filled with LiO() + HO()- 21.iOH(aq)
electrons increases when going down When alkali metals burn in chlorine gas, a white

Group 1. This causes the increase in atomic size. solid, that is metal chloride will be forme
Reactivity increases Sodium, Na The position of valence electrons or example, reaction of sodium with chlorine gas will
is placed further away from the
nucleus of an atom. When the nuclear Attraction force towards the produce sodium chloride.
valence electrons weakens, the electrons are more easily donated. 2Na(s) + Cl (g) > 2NACI(s)

Elements in Group 17 Chemical Properties of Group 17 Elements

F
Cl
Br
I
At Changes of Physical Properties of Elements
Ts when Going Down Group 17

Elements Physical State Melting Point Boiling Point (C) Density (cm¯3) X + e¯ = X¯
(C)
Chlorine, Cl Gas -101 -34 0.00300 Group 17 elements have 7 electrons in the valence shell.
Bromine, Br Liquid -7 59 3.11900 In chemical reactions, these atoms receive one
Solid 114 -42 4.95000 electron and form ion -1 charge
Iodine, I

Going down the group, the increase in molecular size
will cause the attraction force between molecules to
become stronger. The melting point and boiling point

of halogens will increase because more than heat
energy is required to overcome the intermolecular

forces

When halogens react with water, a Based on what you have learned, can you predict
n acidic solution is the physical and chemical properties of fluorine
formed. For example, the reaction
of chlorine with water will and astatine? Generally, all halogens are soluble in
produce hydrochloric acid and organic solvents and do not conduct heat nor
hypochlorous acid.
CL(g) + HO()- HC(aq) + HOC(aq) electricity. Fluorine is a light-yellow poisonous gas.
When halogens react with metal, a This gas which is very reactive and corrosive
metal halide is formed. For example, the
reaction of iron with bromine will produce will cause a strong explosion when combined with
iron(II) bromide. hydrogen gas. Astatine is a rare radioactive
2Fe(s) + 3Br,(1)→ 2FeBr (s) element because it is not chemically stable.
When halogens react with an alkaline
solution, metal halide, metal halite Did you know that the reactivity
and water will of elements decreases when going
be formed. For example, the reaction
of iodine with sodium down Group 17? Increasing
hydroxide will produce sodium atomic size will cause the
iodide, sodium iodate(1) Chlorine. CI
and water.
1,(s)+ 2N2OH(aq)→ Nal(aq) + NaOl(aq) + H,O(1) valence shell to be further from
the nucleus. This will cause the
nuclear attraction force towards
the electrons to become weaker.
Thus, the difficulty in attracting
electrons to fill the valence shell will increase

Elements in Period 3

Changes in Physical Properties of Elements Across Period 3

Increase in the number of protons across
Period 3 will increase the charge in the

atom’s nucleus. The electronegativity of
elements will increase because the nuclear
attraction force towards the electrons
increases

Transition Elements

Special Characteristic for Several Transition
Elements in the Periodic Table of Elements

1. Transition elements function as a catalyst to increase the rate of
reaction without undergoing chemical change at the end of the reaction

All transition elements are metal with the 2. Transition elements are colored ions or compound
following properties: 3. Transition elements have more than one oxidation number
4. Transition elements are form complex ion
• solid with shiny surface
• very hard compared to group 1 and 2
• have high densities
• have high melting points and boiling points

Iron, Fe is used in the Haber Platinum , Pt. used in the Ostwald
Process to produce ammonia Process to produce nitric acid

Uses of Transition Elements in Industry

Vanadium(V) oxide , is used in the Nickel or Platinum is used in the hydrogenation
Contact Process to produce sulphuric acid process in vegetables oils to produce margarine

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