What is the relationship between atoms and molecules?

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Atoms are the smallest form of matter that still retain their properties. Atoms consist of protons, neutrons and electrons, with neutrons and protons forming their nucleus and electrons orbiting around it. For example, sodium (Na) is an atom and consists of 11 protons and electrons each, and 12 neutrons. 

Atoms combine with each other to form molecules.The combinations are in a particular ratio and can be with atoms of the same type or different types. For example, O2 is a molecule formed by the combination of two oxygen atoms. Water, H2O is a molecule formed by the combination of two different atoms- hydrogen (H) and oxygen (O) in a fixed 2:1 ratio.

When atoms combine with each other, they can do so by forming ionic bonds or covalent bonds. In the former, electrons are lost and gained by different atoms, as in sodium chloride, NaCl. In the case of a covalent bond, atoms share their electrons, as in the case of oxygen gas (O2).

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What is the difference between atoms and molecules?

The atom is the smallest particle or fragment of an element that still retains its properties. It consists of a nucleus (made up of protons and neutrons) surrounded by electrons. Atoms combine with each other through chemical bonding to form molecules. Molecules are generally considered to be the smallest fragment that retains the properties  of a chemical compound. Thus, atoms make molecules, molecules do not make atoms. A molecule is generally stable on its own, while an atom can be unstable depending on its electronic configuration. Unless the atom achieves the noble gas configuration, it can lose or gain electron (depending on its electronegativity) to achieve stability. Molecules can be made up of more than one atom, for example oxygen atoms can combine to form an oxygen molecule (O2), they can also combine with hydrogen to form a water molecule (H2O).

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how do atoms differ from molecules?

We can think of matter as being composed of particlesParticles are composed of elements or compounds. Elements and compounds are composed of atoms.

Substances whose atoms are held together by positive and negative charges are called ionic substances. Examples: NaCl, `~MgCl_2`

Substances whose atoms are held together by shared electrons are called covalent substances. The term molecule is another name used to describe a covalent substance. Examples: `~H_2O` , `~CH_4`

Atoms: Atoms are the building blocks of elements and compounds. Atoms contain tiny subatomic particles. The main subatomic particles in atoms are: protons, neutrons, and electrons. Protons and neutrons are located in the nucleus of an atom. Electrons are located in the electron cloud surrounding the nucleus of the atom. 

Therefore, a molecule is an element or compound that is composed of two or more covalently bonded atoms. Example: `~H_2O` is a molecule composed of two hydrogen (H) atoms and one oxygen (O) atom. 

 

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