Group 1 - The Alkali Metals
lithium
Li
sodium
Na
potassium
K
rubidium
Rb
cesium
Cs
francium
Fr
The Group 1 contains 7 elements, but one of them cannot be registered to
this group, because it isn´t a metal. It ´s Hydrogen H2.
We can talk long time about this group, but we try to choose some
interesting facts about it.
All the Group 1 elements are silvery-coloured metals. They are soft, and can be
easily cut with a knife to expose a shiny surface which dulls on oxidation. Next
interesting attribute is, that five of them give a flame a specific colour. Let´s
look at it…
Li
Lithium was discovered in 1817 by Johann Arfvedson (Sweden). Lithium is the lightest of all
metals, with a density only about half that of water.
It does not occur free in nature; combined it is found in small units in nearly all igneous rocks
and in the waters of many mineral springs. It reacts with water, but not as vigorously as sodium.
Lithium imparts a beautiful crimson color to a flame, but when the metal burns strongly, the
flame is a dazzling white. Among others lithium compounds are used in dry cells and storage
batteries.
Na
Sodium was long recognized in compounds only, sodium was first isolated by Sir Humphrey Davy
in 1807 by electrolysis of caustic soda.
Sodium is the fourth most abundant element on earth.
Imparts a beautiful crimson color to a flame
(Metallic sodium is vital in the manufacture of esters and in the preparation of organic
compounds.)
Sodium metal should be handled with great care. It cannot be maintained in an inert atmosphere
and contact with water and other substances with which sodium reacts should be avoided.
K
Potassium was discovered in 1807 by Sir Humphrey Davy, too , who got it from caustic potash
(KOH); this was the first metal isolated by electrolysis.
The metal is the seventh most abundant of the earth's crust.
Potassium is also found in the ocean, but is present only in relatively small amounts, compared to
sodium.
Potassium is an essential constituent for plant growth and is found in most soils.
Rb, Cs, Fr
Rubidium and Cesium were recognized by Bunsen and Kirchoff in second half of 19th century,
Francium was discovered in 1939 in Paris (Marguerite Perey).
There are some interesting facts about these elements:
Rubidium, alcalic metal, can be liquid at room temperature.
Cesium is the most electropositive and most alkaline element, for example it reacts explosively
with cold water, and reacts with ice at temperatures above -116C.
Francium is the heaviest known member of the alkali metals series.
QUIZ:
1.How many elements is in the Group 1?
a) 7
M
b) 8
K
c) 6
A
d) 6 and half
D
2. Lithium compounds are used..
a) in the manufacture of Teflon
b) as a reducing agent in preparing other metals.
c) in dry cells and storage batteries.
d) in manufacture of Coca Cola
U
I
E
X
3. What rank is Sodium in abundance on earth?
a) fiveth
b) fourth
c) sixth
d) fourty-seventh
4. Where can we find a few of Potassium?
a) in air
b) in ocean
c) in fruit
d) in a bathrom
5. Which element was recognized the latest?
a) Fr
b) Cs
c) Rb
d) each were recognized in the same time
6.How did you like this presentation?
a) It was good.
b) It was realy good.
c) Is it the last question?
d) It was famous!!
Words:
contain
R
T
D
S
E
A
U
V
L
K
A
C
S
S
S
S
skládat se (z čeho), obsahovat
expose
shiny
surface
colour flame
attribute
igneous rock
spring
fused
appearance
vigorously
crimson
impart
dazzling
among others
dry cell
storage battery
recognize
abundance
maintain
comparison
předložit,odhalit
lesklý
povrch
barvit plamen
vlastnost, znak
vyvřelá hornina
pramen
roztavený
výskyt, zjevení
silně
karmínový
propůjčit, předat
oslnivý
mimo jiné
baterie
akumulátor
poznávat
zastoupení
udržovat
porovnání