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Unit 1 Main groups in
Lesson3 the modern periodic table

From the main groups in the modern periodic table:

1- group (1) or (1A) : alkali metals group
2- group (17) or (7A) : halogens
3- group (18) or (zero group) : inert gases

Alkali metals group

(Group 1A)

Location: They are the first group of s-block

Name: They are known as alkaline metals bec. their elements

react with water forming alkaline solution

Ex: 2Na + 2 2O 2NaOH+ H2

Physical • All of them are soild and they have a metallic

properties: luster

• They are good conductors of heat

• They are good conductors of electricity

Most of its elements have low density

Ex:

Lithium (Li) float on water

Sodium (Na)

Potassium (K)

Rubidium (Rb) sink in water
Cesium (Cs)

2nd Prep. First Term 25 18