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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nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.