What is molecule, element, and compound? What is the relationships between them?
Check these sites.
http://education.jlab.org/qa/compound.html
http://www.nyu.edu/pages/mathmol/textbook/compounds.html
Your teacher should have added the term "formula unit" to the list. Many compounds are not made up of molecules, but formula units.
A molecule is a combination of two or more atoms chemically bonded together. Each atom consists of a nucleus (containing protons and neutrons) and orbiting electrons. Molecules can be formed by the same type of atoms (like oxygen gas, O2), or different types of atoms (like water, H2O).
An element is a substance composed of only one type of atom. There are 118 known elements, each with its own unique properties. Examples of elements include oxygen (O), carbon (C), and hydrogen (H).
A compound is a substance formed by the chemical combination of two or more different elements in a fixed ratio. Compounds have properties that are distinct from the elements they are composed of. For example, water (H2O) is a compound formed by the combination of hydrogen and oxygen.
The relationship between these terms can be understood as follows:
- Both elements and compounds are made up of atoms. However, compounds have atoms of different elements bonded together, while elements consist of only one type of atom.
- A compound can be viewed as a group of molecules. Molecules represent the smallest unit of a compound, whereas elements cannot be broken down further into smaller substances (except through nuclear reactions).
- Elements exist independently and can be found in nature, while compounds are formed through chemical reactions.
- Molecules can be both elements (such as O2) and compounds (such as H2O), depending on the types of atoms bonded together.
In summary, elements are the building blocks of matter, compounds are formed by the combination of different elements, and molecules can refer to both elements and compounds depending on their composition.