Difference Between Atoms And Molecules

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What Is An Atom?

An atom is the smallest unit of matter that retains all of the chemical properties of an element. Every solid, liquid, gas and plasma is composed of neutral or ionized atoms.

An atom is composed of two regions the nucleus which is in the center of the atom and contains protons and neutrons and the outer region of the atom which holds its electrons in orbit around the nucleus. Atoms have different properties based on the arrangement and number of their basic particles.

All atoms are electrically neutral because every atom has an equal number of electrons and protons. Nearly all of the atom’s mass is located in the nucleus. The nucleus is tiny compared with the total size of the atom.

Atoms are generally spherical, although there are indications that atoms of the very heaviest elements may exist as squashed spherical shapes.

Atoms of the same element or of different elements can join with chemical bond together to form molecules which then interact to form solids, gases or liquids.  They may also ionize to form ionic compounds. For example, water is composed of hydrogen and oxygen atoms that have combined to form water molecules. The number of atoms that constitute a molecule is referred to as atomicity.

Examples Of Atoms

  • Neon (Ne)
  • Hydrogen (H)
  • Iron (Fe)
  • Calcium (Ca)
  • Argon (Ar)
  • Plutonium (Pu)

Characteristics Of Atoms

  • An atom can be described as the smallest unit of an element which may or may not exists independently.
  • Atoms consist of subatomic particles: Protons, electrons and neutrons.
  • An atom has a nucleus surrounded by electrons.
  • An atom cannot be separated into subatomic particles with the help of chemical reactions or changes.
  • Atoms have electrostatic force of attraction between the positive nucleus and electrons.
  • With exception of noble gas atoms, atoms are highly reactive i.e they participate in the chemical reaction without additional decomposition into subatomic units.
  • The shape of an atom is spherical.
  • Atom may or may not exist in the free state.
  • Atoms may or may not possess properties of matter.
  • An atom can neither be seen through naked eye nor through magnifying lens.
  • Atoms have electrons on the outer shell and in this regard, atoms may not remain stable all the time.
  • C, O, N, H are examples of atoms.
  • Atoms are generally made up of nuclear bond.
  • When atoms combine together in varying numbers, molecules of different properties can be formed.

What Is A Molecule?

Molecule can be described as the smallest particle of an element or a compound, which is capable to exist independently and shows all the properties of the respective substance. A molecule may be homo-nuclear, which means it consists of atoms of one chemical element as with oxygen (O2) or it may be hetero-nuclear, a chemical compound composed of more than one element as with water ( two hydrogen atoms and one oxygen atom; H2O).

A molecule is formed when two or more atoms of an element chemically join together. If the types of atoms are different from each other, a compound is formed. Molecules have chemical attraction or bonding between atoms and have single and triple bonds between constituent atoms. The geometry and composition of a molecule will determine its chemical and physical properties. A molecule can be separated into atoms with the help of chemical reactions.

Molecules are neutral and carry no charge; this property distinguishes them from polyatomic ions such as nitrate (NO3-). Molecular size varies depending on the number of atoms that make up the molecule. Most molecules are too small to be seen with the naked eye.

Examples Of Molecules

Molecules may be simple or complex. Here are examples of common molecules:

  • H2O (Water)
  • N2 (Nitrogen)
  • O3 (Ozone)
  • CaO (calcium oxide)
  • C6H12O6 (Glucose)
  • NaCl (Table salt)

Characteristics Of Molecules

  • Molecules are made up of two or more elements. They do not display the individual properties of the constituent elements.
  • Molecules consist of more than two atoms which can be either of the same element or of different elements.
  • A molecule can be separated into atoms with the help of chemical reactions.
  • Molecules have chemical attraction or bonding between atoms and have single and triple bonds between constituent atoms.
  • Molecules are less reactive as they do not take part in the chemical reaction.
  • The shape of a molecule can be linear, angular or rectangular.
  • Molecules exist in the free state.
  • Molecules always possess the properties of matter.
  • Molecules are not visible to naked eye, though they can be seen through highly magnifying microscope.
  • Molecules are stable.
  • H2, N2, NO3 etc are examples of molecules.
  • Molecules are generally made up of covalent bond.
  • When molecules combine in any numbers, a simple product (Compound) is formed.

Also Read: Difference Between Covalent Bonds And Hydrogen Bonds

Difference Between Atoms And Molecules In Tabular Form

BASIS OF COMPARISON ATOMS MOLECULES
Description An atom can be described as the smallest unit of an element which may or may not exists independently.   Molecules are made up of two or more elements. They do not display the individual properties of the constituent elements.  
Components Atoms consist of subatomic particles: Protons, electrons and neutrons.   Molecules consist of more than two atoms which can be either of the same element or of different elements.  
Separation An atom cannot be separated into subatomic particles with the help of chemical reactions or changes.   A molecule can be separated into atoms with the help of chemical reactions.  
Bonding Molecules have chemical attraction or bonding between atoms and have single and triple bonds between constituent atoms.   Atoms have electrostatic force of attraction between the positive nucleus and electrons.  
Reactivity With exception of noble gas atoms, atoms are highly reactive i.e they participate in the chemical reaction without additional decomposition into subatomic units.   Molecules are less reactive as they do not take part in the chemical reaction.  
Shape The shape of an atom is spherical.   The shape of a molecule can be linear, angular or rectangular.  
State Atom may or may not exist in the free state.   Molecules exist in the free state.  
Properties Of Matter Atoms may or may not possess properties of matter.   Molecules always possess the properties of matter.  
Visibility An atom can neither be seen through naked eye nor through magnifying lens.   Molecules are not visible to naked eye, though they can be seen through highly magnifying microscope.  
Stability Atoms have electrons on the outer shell and in this regard, atoms may not remain stable all the time.   Molecules are stable.  
Examples C, O, N, H H2, N2, NO3
Type Of Bonds Atoms are generally made up of nuclear bond.   Molecules are generally made up of covalent bond.  
Combination When atoms combine together in varying numbers, molecules of different properties can be formed.   When molecules combine in any numbers, a simple product (Compound) is formed.