Complete the sentence Select all that apply The last element in periods 2-7 always has: the properties of a noble gas the lowest atomic mass because it is a gas five electrons in the outermost energy level eight electrons in the outermost energy level

The last element in periods 2-7 always has:<br /><br />- the properties of a noble gas<br />- eight electrons in the outermost energy level<br /><br />These elements are known as noble gases, and they have a full valence shell with eight electrons (except for helium in period 1, which has two electrons). This configuration makes them very stable and unreactive.