Question

1. pure sodium metal reacts violently with water to produce sodium hydroxide (naoh). the reaction occurs very quickly and releases a great deal of heat. which of the following best describes why this reaction occurs so quickly and so violently?

hydroxide ions have very low electronegativity.
hydroxide ions have valence electrons in excess of a full octet.
the oxygen in the water reacts with the sodium metal to produce flammable oxygen gas.
sodium metal has only a single valence electron and has a very low ionization.
clear all

Explanation:

• Sodium is in Group 1 of the periodic table. Elements in Group 1 have one valence electron.
• Sodium has a low ionization energy. This means it is relatively easy for sodium to lose its single valence electron.
• When sodium reacts with water (\(2Na + 2H_2O=2NaOH + H_2\uparrow\)), the low ionization energy of sodium allows it to quickly transfer its electron (oxidation of sodium: \(Na - e^-=Na^+\)) and react vigorously.
• Hydroxide ions (\(OH^-\)) have a full - octet - like structure (oxygen has 8 electrons around it when considering the covalent bond with hydrogen and the negative charge). They do not have electrons in excess of a full octet. Also, hydroxide ions have relatively high electronegativity (oxygen is electronegative). And in the reaction of sodium with water, the hydrogen in water is reduced (\(2H_2O + 2e^-=H_2\uparrow+ 2OH^-\)) to form hydrogen gas, not oxygen gas.

Answer:

Sodium metal has only a single valence electron and has a very low ionization.