Which atom in the ground state has an outermost electrons in the shells of a calcium energy

The answer is Cs, no. 2.

Cesium (Cs) is an element which has an outermost electron with most energy in the ground state. 

 Cesium (Cs), Lithium (Li), Potassium (K), and Sodium (Na) are elements which belong to the group 1 family, the alkali metals. Each has a valance of 1 and wants to release/ lose this e- (electron) to be isoelectronic with the nearest noble gas. Based on the periodic trends, an atom’s radii will raise going down a group.  

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metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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