Based on the above sequence, the chemical reactions involving silicon (Si) progress as follows:

Silicon (Si) reacts with oxygen (O2) to form silicon dioxide (SiO2).Silicon dioxide (SiO2) reacts with sodium oxide (Na2O) to form sodium silicate (Na2SiO3).Sodium silicate (Na2SiO3) can further react with water (H2O) to form orthosilicic acid (H4SiO4).Orthosilicic acid (H4SiO4) can dehydrate to form silicon dioxide (SiO2).Silicon dioxide (SiO2) can further react with magnesium ions (Mg2+) to form magnesium silicide (Mg2Si).Silicon (Si) can react with hydrogen gas (H2) to form silane (SiH4).Silane (SiH4) can decompose to form silicon (Si).Silicon (Si) can also react with oxygen (O2) to form silicon dioxide (SiO2).

These chemical reactions demonstrate the versatility of silicon in forming various compounds and undergoing different reactions.