SS 2 CHEMISTRY
THE PERIODIC TABLE
BY
MR. OLASUPO K.A
08023458888
[email protected]
REFERENCES
1. COMPREHENSIVE CERTIFICATE CHEMISTRY
By GNC Ohia and Others.
2. IGCSEB CHEMISTRY
By Earl and Wilford.
How was the periodic table developed?
Dmitri Mendeleev (1869, Russian)
Organized elements by increasing atomic mass.
Elements with similar properties were grouped together.
There were some discrepancies
Henry Mosely (1913, British)
Organized elements by increasing atomic number.
Resolved discrepancies in Mendeleev’s arrangement.
.
The periodic table
Arranging all the elements by their atomic number and their properties led to the
creation of…
…the periodic table
H
Li
He
Be
B
C
N
O
F
Ne
Na Mg
Al
Si
P
S
Cl
Ar
Cu Zn Ga Ge As Se
Br
Kr
I
Xe
K
Ca Sc
Rb Sr
Ti
V
Cr Mn Fe Co
Ni
Y
Zr
Nb Mo Tc Ru Rh Pd Ag Cd
In
Sn Sb Te
Cs Ba La
Hf
Ta
Tl
Pb
Bi
Po
At
Rn
Fr
Rf Db Sg Bh Hs Mt Ds Rg
?
?
?
?
?
?
Ra Ac
W
Re Os
Ir
Pt
Au Hg
?
Columns of elements
What are columns of elements called?
1
2
groups
3
4
5
6
7
0
Group – A column in the periodic table
containing elements with the same
number of outer shell electrons and
similar chemical properties.
Rows of elements
What are rows of elements called?
periods
1
2
3
4
5
6
7
Period – A row in the periodic table
containing elements with the
same number of full electron
shells.
Groups and periods
Patterns: metals and non-metals
Where are these different types of elements grouped together in the periodic
table?
 metals
on the left and centre
 non-metals
on the right (except hydrogen)
 semi-metals
between metals and non-metals
Semi-metals have some properties similar to metals and other properties similar
to non-metals.
Patterns: reactivity of metals
What happens to the reactivity of metals along a period?
What happens to the reactivity of metals down a group?
Which is the most reactive metal?
Li
Be
increase in reactivity
Na Mg
K
Al
Ca Sc
Rb Sr
Y
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn
Cs Ba La Hf Ta
W Re Os
Ir
Pt Au Hg Tl Pb Bi Po
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg
increase in reactivity
Patterns:
reactivity
of
non-metals
Group 0 elements are the most unreactive of all elements.
For the remaining non-metals and
semi-metals, reactivity increases up a
group and along a period from left to
right.
increase in reactivity
He
Which is the most reactive nonmetal/semi-metal?
increase in reactivity
B
C
N
O
F
Ne
Si
P
S
Cl
Ar
Ge As Se Br
Kr
Sb Te
Xe
I
At Rn
unreactive
Electron trends in the periodic table
Trends down a group:
 the number of outer shell electrons is the same;
 the number of complete electron shells increases by one.
The number of a group is the same as the number of electrons in the
outer shell of elements in that group,
except for group 0.
Trends across a period:
 the number of outer shell electrons increases by one;
 the number of complete electron shells stays the same.
The point at which a new period starts is the point at which electrons
begin to fill a new shell.
NAMES OF GROUPS IN THE PERIODIC TABLE
GROUP 1- ALKALI METALS
GROUP 2- ALKALINE EARTH-METALS
GROUP 7- HALOGENS
GROUP 0- NOBLE GASES
BETWEEN GROUP 2 AND 3- TRANSITION METALS
ASSIGNMENT
The diagram shows part of the Periodic Table.
Answer these questions using only the elements shown in the
diagram.
Write down the symbol for an element which
(i) is a transition metal.
(ii) Is an alkali metal.
(iii) has six electrons in its outer shell.
(iv) Most reactive metal.
(v) Is an halogen.
(vi) has a higher proton (atomic) number than iron.
(vii) Most reactive non-metal
(viii) A noble gas
(ix) Has four(4) electron shells
(x) Has eight(8) electrons in its outer shell.