Short Answer TypeWhat happens when a burning magnesium ribbon is introduced into a jar of carbon dioxide?
Long Answer TypeName the elements of group 1. Write their electronic configurations.
The metallic elements lithium (Li), sodium (Na), potassium(K), rubidium (Rb), caesium (Cs) and francium (Fr) constitute group 1 of the periodic table. Francium is a radioactive element. They are known as alkali metals because their hydroxides are strong alkalies or bases.
Electronic configuration: The atoms of alkali metals have one electron in s-orbital outside a noble gas core. Therefore, their general electronic configuration is:
[Noble gas]ns1 where n = 2 to 7
The electronic configurations of alkali metals are given below:
| Element | At No | Electronic configuration |
| Lithium (Li) | 3 | [He]2s1 |
| Sodium (Na) | 11 | [Ne] 3s1 |
| Potassium (K) | 19 | [Ar] 4s1 |
| Rubidium (Rb) | 37 | [Kr] 5s1 |
| Caesium (Cs) | 55 | [Xe] 6s1 |
| Francium (Fr) | 87 |
[Rb] 7s1 |
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