Elements, Molecules and Compounds

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What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and carbon (C).

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What is a molecule?

Back

A molecule is a group of two or more atoms bonded together. It can consist of the same or different types of atoms. For example, O2 (oxygen) is a molecule made of two oxygen atoms.

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Front

What is a compound?

Back

A compound is a substance formed when two or more different types of atoms bond together chemically. For example, water (H2O) is a compound made of hydrogen and oxygen.

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Front

How many atoms are in a molecule of water (H2O)?

Back

A molecule of water (H2O) contains 3 atoms: 2 hydrogen atoms and 1 oxygen atom.

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Front

What distinguishes a compound from a mixture?

Back

A compound is a chemical combination of two or more different elements, while a mixture is a physical combination of two or more substances that retain their individual properties.

Front

What is the chemical formula for carbon dioxide?

Back

The chemical formula for carbon dioxide is CO2, which consists of one carbon atom and two oxygen atoms.

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Front

What is the difference between an atom and a molecule?

Back

An atom is the smallest unit of an element, while a molecule is a group of two or more atoms bonded together.

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Front

Can a molecule be an element?

Back

Yes, a molecule can be an element if it consists of two or more atoms of the same element, such as O2 (oxygen gas).

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Front

What is the term for a substance made of only one type of atom?

Back

The term is 'element.' An example is gold (Au), which is made up of only gold atoms.

Front

What is ammonia's chemical formula?

Back

The chemical formula for ammonia is NH3, which consists of one nitrogen atom and three hydrogen atoms.

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