When different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical__5___.
When different elements are chemically combined, with the atoms held together by chemical bonds, they form chemical__5___.
chemical
chemical
A chemical is any aspect of a substance which is only seen by means of a chemical reaction (反应).
A chemical is any aspect of a substance which is only seen by means of a chemical reaction (反应).
A chemical compound that contains two atoms of oxygen and one atom of another chemical element is called ______
A chemical compound that contains two atoms of oxygen and one atom of another chemical element is called ______
To identify a substance, chemists observe two distinct types of , physical and chemical, which are related to physical and chemical that matters undergoes.
To identify a substance, chemists observe two distinct types of , physical and chemical, which are related to physical and chemical that matters undergoes.
Nuclear rockets, in contrast to their chemical
Nuclear rockets, in contrast to their chemical
Water is a kind of chemical substance.
Water is a kind of chemical substance.
The changes of chemical reactions include:
The changes of chemical reactions include:
化学性突触（chemical synapse）
化学性突触（chemical synapse）
Carbon-containing compounds commonly exist as ___________________, molecules with the same chemical bonds and same chemical formula but different configuration, the fixed spatial arrangement of atoms.
Carbon-containing compounds commonly exist as ___________________, molecules with the same chemical bonds and same chemical formula but different configuration, the fixed spatial arrangement of atoms.