An oxide is a compound formed between an element and oxygen. Oxides are very widespread, and their acid–base character varies systematically across the periodic table: metal oxides tend to be basic, while non-metal oxides tend to be acidic. Examples include the basic oxide calcium oxide and the acidic oxide carbon dioxide.

氧化物是元素与氧形成的化合物。氧化物极为普遍,其酸碱性质沿周期表有规律地变化:金属氧化物往往呈碱性,而非金属氧化物往往呈酸性。例如碱性氧化物氧化钙和酸性氧化物二氧化碳。