Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

s-Block Elements
Physical properties of s-block elements
Physical State
ALKALI METAL






ALKALINE EARTH METAL

One electron in outermost shell &
General formula ns1
Francium is radioactive element
...

Alkali metals are paramagnetic,
diamagnetic and colorless in form
of ions
...

All are grayish white
...

These are diamagnetic and colorless
in form of ions or in metal states
...

Li < Na < K < Rb < Cs < Fr

ALKALINE EARTH METAL




Smaller than IA group elements,
since extra charge on nucleus
attracts the electron cloud
...

Be < Mg < Ca < Sr < Ba
In s-block elements : Be is the
smallest, Cs is the biggest

Softness
ALKALI METAL
Alkali metals are soft because ofa) Large atomic size
b) BCC crystal structure (HCP in Li)
c) Loose packing (68% packing
efficiency)
d) Weak metallic bond
 Cs is the softest metal in s-block


Atomic size ∝

ALKALINE EARTH METAL
These metals are slightly harder than
IA group elements because ofa) Smaller atomic size
b) FCC, HCP crystal structures
c) Packing efficiency 74%
d) Stronger metallic bond due to
presence of two electrons in
valence shell
...




1
1
∝ softness ∝
strength of metallic bond
melting & 𝑏𝑜𝑖𝑙𝑖𝑛𝑔 𝑝𝑜𝑖𝑛𝑡

Melting point & Boiling point
ALKALI METAL






Weak interatomic bonds are due to
their large atomic radii and presence
of only one valence electron hence
melting point and boiling point are
low
...


ALKALINE EARTH METAL






Metallic bond is stronger than IA
group due to smaller atomic size and
two electrons in valence shell hence
melting point and boiling point are
higher
...


𝑀𝑒𝑙𝑡𝑖𝑛𝑔 & 𝐵𝑜𝑖𝑙𝑖𝑛𝑔 𝑝𝑜𝑖𝑛𝑡 ∝ 𝑆𝑡𝑟𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑚𝑒𝑡𝑎𝑙𝑙𝑖𝑐 𝑏𝑜𝑛𝑑

Ionization Potential (I
...
)
ALKALI METAL






First Ionization Potential (I
...
) is very
less because of bigger atomic size
and only one electron in outer most
shell
...

Decreasing order of ionization
potential –
Li > Na > K > Rb > Cs
(1st and 2nd ionization potential
difference > 16eV)

ALKALINE EARTH METAL





First ionization potential is higher
than IA group because of smaller
atomic sixe and completely filled sorbital (stability)
Second ionization potential is lesser
than IA group
...
Electro
positive property increases from Li
to Cs

ALKALINE EARTH METAL


Their atomic size is smaller than IA
group so these are lesser electro
positive than IA group

---