Electron configuration, continued noble gases

If this pattern continued, you would expect boron to lose three electrons to attain the helium configuration. Sometimes, boron does react by losing electrons, but often it reacts by sharing electrons. Boron is the only metalloid in the period. That means boron sometimes behaves like a metal and loses electrons like its neighboring metals, lithium and beryllium. When it loses electrons, boron achieves the noble-gas configuration of helium. But more often, boron acts like a nonmetal and shares electrons. Boron is unusual because it has only three electrons to share and cannot acquire an octet of electrons by just sharing. Later, you ll learn more about boron s chemistry. 

Neon is a noble gas. The electrons continue to fill 3s, 3p shells for elements from Na to Ar. These configurations are... 

Strategy (a) Use the building-up principle discussed in Section 2.2 to write the electron configuration with principal quantum number n = 1 and continue upward until all the electrons are accounted for. (b) To determine whether the atom should be classified as a representative element, a transition metal, or a noble gas, consider its electron configuration characteristics, (c) Examine the pairing scheme of the electrons in the outermost shell. The element will be diamagnetic if all electrons are paired and paramagnetic if some are unpaired. 

We began to consider the electron configurations of ions in Section 7.4. In light of our examination of ionic bonding, we will continue with that discussion here. The energetics of ionic bond formation helps explain why many ions tend to have noble-gas electron configurations. For example, sodium readily loses one electron to form Na, which has the same electron configuration as Ne ... 

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