O Level Chemistry & IP Chemistry Notes by 10 Year Series Author - Chemistry Specialist

O Level Chemistry Made Easy

O Level Chemistry: Difference between Atom, Molecule & Particle

Can you differentiate between Atom, Molecule & Particle? I received an enquiry from a subscriber to SimpleChemConcepts.com yesterday and i realized that many students have misconception of the different definitions given to them.

When we say Avogadro’s Number states that there are 6 x 10^23 particles for 1 mole of substances, the “particles” is actually a general term.

“Particles” can mean atoms (He gas atoms), molecules (H2 gas, N2 gas molecules), ionic substances (NaCl ionic salt) or even the ions itself (Chloride Cl- anions, Mg2+ cations).

Do not confuse between this “Particle” as the other “Sub-atomic Particle” that is mentioned in the topic of Atomic Structure. The “Sub-atomic Particle” refers to the PEN – Proton, Electrons & Neutrons. These “Sub-atomic particles are smaller than the atoms themselves.

By the way,

Atom is defined as the the smallest component of an element having the chemical properties of the element. Example, any of the elements you see on the periodic table exist as atom.

&

Molecule is defined as a group of two or more atoms held together by covalent bonds. When atoms combine by sharing electrons, molecules are formed. Example, H20 molecules, CO2 molecule, Cl2 gas molecule.

Hope the above explaination helps. Do leave your comments in the “comment” section below.

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Sean Chua
Many know me as the Ten Year Series book author for JC A-Level H2 Chemistry and O-Level Pure Chemistry. My 19+ years of coaching experience (since 1999) with more than 1500 students from 180+ JCs and Secondary Schools has allowed me to understand the true reasons why students are not able to perform well in Chemistry. Most importantly, my strength lies in using everyday analogies (even grandmothers can understand!) to simplify abstract concepts. Also, my teaching methodology has been designed to be fun, enjoyable and effective for my students. If you want to have an enjoyable time learning Chemistry and being motivated to excel in Chemistry, contact me today at 98287357

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Comments

  2. sir pls help me with this question: in a volumetric analysis, 24.80cm3 of a mineral acid Y neutralized 25.0cm3 of a solution containing 5.83g of Na2CO3 per dm3. From the info given above, calculate the amount (in moles) of an acid Y used?. Pls help me i don’t knw hw to begin

  3. Particles is a GENERAL word used in Chemistry to describe either atoms, molecules, ions or radicals, etc.

    Yes, we can also say that atoms are particles. It all depends on how the questions are being phrased.

    If the question state that there is a particle X that has 20 protons, 20 electrons and 20 neutrons, then this particle will be Ca atom.

    But if question state that there is a particle X that has 20 protons, 18 electrons and 20 neutrons, then this particle will be Ca2+ ion.

    Hope this is clear.

  4. Are Atoms and Particles the same thing or not?, Because I still don’t understand

    Thanks,
    Emmz

  6. The word “particle” is a GENERAL word that is used to describe alot of things in Chemistry…it can refer to atoms, molecules, ions, electrons, free radicals, etc.

    Just remember, it is very a general word….what it really describes all depends on the question or statement.

  7. Hi Kashif Khan,

    Noble Gases (your Group VIII or O elements) exists as individual atoms.

    They have stable/complete valence shell and thus a stable electronic configurations.

    This makes them very stable and inert / unreactive, and thus Ar, Ne, He, etc does not exists as molecules.

    Hope this helps. =)

  8. As i mentioned above, a molecule is formally defined as “a group of two or more atoms held together by covalent bonds. When atoms combine by sharing electrons, molecules are formed. Example, H20 molecules, CO2 molecule, Cl2 gas molecule.”

    I assume “C” refers to an unknown element.

    Then, C will be an atom of an element. If it combines with another C atom and forms C2, then it is a covalent molecule.

    Diatomic Molecule refers to any molecule that is formed due to covalent bonding of 2 atoms. It can be same type of atoms (we call this Molecules of Elements) or different types of atoms e.g. CD2 (we call this Molecules of Compounds).

    Hope the above explanation is useful to you.

    Do check with your school teacher (Chemistry) to understand the essential concepts in the topic Chemical Bonding.

  9. wait isn’t a molecule that has two atoms called a diatomic molecule?

    C= molecule?
    C2= diatomic molecule?

    would C2 also be just a molecule too?

  10. Wow I get it. I learned the difference between molecules and compounds like 6th or 8th grade but I didn’t really process the information. Thanks for jogging my memory!!

  11. Sir then individual Noble gas atom (He, Xe etc) can be called as molecule or not?
    As it can exist independently and do all the individual actions as stable molecule can do ?
    Regards

  12. I get what an atom is, and what a molucule is…but i dont understand what a particle is. hope u can help….fast!

  15. Hi Sean, just wanted to say thanks, its very odd that teachers don’t stress the differences, or perhaps I missed that day the teacher did in fact teach the differences. Nonetheless it helped me a lot, thanks again.

  16. element actually comprises of many many atoms but not chemically combined
    molecule is made when atoms combined chemically by covalent bonding.example H2O ,CO2
    molecule of compound-when different atoms combined chemically.example CO2 H2O
    molecule of element-when same atoms combined chemically
    example H2
    sir am i right?

  17. I understood about the different between molecules and compound but what is the different between molecules and elements?? please answer me…many tell that atom is the smallest particle of an element and also molecules is the group of atoms….then how can we get molecules of an element?? am completely baffled…someone answer me please..

  18. We say that a molecule is made up of two or more atoms chemically joined together. Then it means that the atoms are from the same element? (well they can be) but then water H20 is can be a molecule and compound. How do we tell what is a molecule and what is a compound?

    and what is a covalent bond?

  19. Hi Coty.

    I am glad to hear that.

    We thank you for your encouraging words.

    Feel free to drop us any comments. Cheers!

  20. Thanks so much for your help! Mole and molecules always confused me but since you put it that way it makes sense now. Just to let you know I made a 94 on my college chem. exam and it was the highest in my class, so you helped a ton!

    Thanks again and God bless,
    Coty

  21. Hi Russell,

    This is the basic essential concepts of Chemistry that are causing some junior chemistry students some problem. In Singapore, the Sec 3s (some Sec 2s) are having the same misconceptions on these.

    Molecule is NOT THE SAME as Element.

    Molecules are made up of 2 or more atoms that are chemically combined together. Element is the “name” that describes the atoms, and the total number of Elements are stated in the Periodic Table.

    Hope this information helps. =)

    To Your Academic Success in Chemistry,
    Sean Chua

  22. Hi Coty,

    There are different.

    The unit of measurement for atoms and molecules is the Mole. The mole is also the S.I. Unit for chemical quantity i.e. how much. The symbol for the mole is mol.

    Molecule is a group of 2 or more atoms that are chemically combined together.

    Hope this information helps. =)

    To Your Academic Success in Chemistry,
    Sean Chua

  23. Hey Sean, Element is define as a pure substance that are make up of a single type of atoms. And molecules are make up of Atoms. So doesn’t that mean that a Molecule is the same as an Element?

  24. Hey, I’m doing problems in my chem class involving molecules and mols. What is the difference (if any) between a mol and a molecule? Are they the same thing?

  25. Very valid question for those just started on learning Chemistry.

    Definition as follows:

    ATOMs
    – The smallest particle of an Element that has the chemical properties of that element

    MOLECULEs
    – A molecule is a group of two or more atoms that are chemically combined together

    IONs
    – An ion is basically a charges particle.
    – Anion (-ve ion) are formed when an atom gain electron (s)
    – Cation (+ve ion) are formed when an atom lose electron (s)

    Hope this helps you in your learning.

    Cheers
    Sean

  26. Hi Nurul,

    Over the last 18 months, i have written several blogposts on Organic Chemistry.

    Do a search on the right hand side SEARCH bar with the key word “Organic Chemistry”.

    All the best to your learning of chemistry,
    Sean

  28. hye, sean. i just started my chemistry class. can u please explain to me what are the differences btween atoms, molecules and ions?

    thank you.

  29. Hi riva,

    When we say O2 – it refers to the molecular compound Oxygen Gas.

    For 2O – it shows that there are 2 Oxygen Atoms that are going to react with other substances.

    Hope this information helps.

    PS: Do try out other questions in this blog

    To Your Academic Success in Chemistry,
    Sean Chua
    Master Trainer @ SimpleChemConcepts.com
    Author of Up Your Chemistry Grades Now! book

  31. Hi Kimberly,

    They are 2 ions in KCl, namely K+ and Cl- ions

    KCl is an ionic compound and there are electrostatic forces of attraction between the positive and negative ions. This attraction is known as Ionic Bonding.

    H2O is a covalent molecule. There is covalent bonding between the H and O atoms. But between the H2O molecules, they are held together weekly by weak van der Waals forces.

    Hope this is helpful to you.

    PS: Where are you from? Just started to learn Chemistry? Sec 3?

    To Your Academic Success in Chemistry,
    Sean
    Master Trainer
    Author

  32. compunds are made up of molecules I think. For example, water is a compound, and it’s consisted of many many water molecules

  33. 2 quistions….first how many ions are in KCl? and second….what do the attractions between H20 and chloride ions look like? i hope you can help me…thanks

  34. Hi Lorna,

    I am glad you are learning something here.

    Rmbr that Chemistry is all about basic essential concepts. You need to have a strong foundation of these essential concepts in order to score well for application topics later on.

    Check out other questions posted and discussed in this blog, by selecting the ?Question and Answer? under the Category Box on the RHS.

    If you have a specific topic that you would like to revise on, enter the Topic Keywords in the ?Search for Chemistry Topics? field on the RHS.

    All The Best To Your Academic Success in Chemistry,
    Sean
    Master Trainer
    Author

  35. Hi Emma,

    Apparently, different books present them in different ways. It is confusing if you do not have a coach or teacher to guide you through those assessment or textbooks.

    In general, “Molecule” is NOT ” Compound”.

    Refer to my earlier comment above.

    Compound can refer to both Ionic substances as well as Covalent substances.

    Molecule is only associated to Covalent substances.

    Hope this makes it even clearer for you.

    Cheers
    Sean
    Master Trainer
    Author

  36. Hi Maureen,

    I am glad you have learned something about to improve your grades in Chemistry.

    Rmbr that Chemistry is all about basic essential concepts. You need to have a strong foundation of these essential concepts in order to score well for application topics later on.

    Check out other questions posted and discussed in this blog, by selecting the “Question and Answer” under the Category Box on the RHS.

    If you have a specific topic that you would like to revise on, enter the Topic Keywords in the “Search for Chemistry Topics” field on the RHS.

    All The Best To Your Academic Success in Chemistry,
    Sean
    Master Trainer
    Author

  37. Thank you very much for explaining the difference between a molecule, atom and particle. I have always been stuck on which one to use (especially when it comes to molecules/particles) so now I know!
    Lorna.

  40. Hi Sandy,

    Yes. You are spot on.

    Molecules are defined as a group of 2 or more atoms that are held together by
    covalent bonds, which can be:

    A) Molecules of Elements – made up of same elements e.g. Cl2, H2, O2, N2,etc

    B) Molecules of Compounds – made up of different elements e.g. CO2, H2O, etc

    Hope this helps.

    PS: You can become a subscriber of ths Chemistry Blogsite by signing up at:
    http://www.simplechemconcepts.com/balancechemicalequations.html

    Rgds,
    Sean
    Author of SimpleChemConcepts.com

  41. means that a compound could also be a molecule..
    and that molecule are made of same elements
    while compound could be made up of different elements?

  42. Very good question Jennifer.

    First, you would need to know the difference between Elements, Compounds &
    Mixtures. When 2 or more elements come together without any chemical reactions,
    then a Mixture is formed. When you have 2 or more elements that comes
    together in a chemical reaction (light and/or heat given off), they formed a new
    substance that have different properties from those elements they are formed,
    we called these substance as Compounds.

    Compounds can be:
    a) Ionic Compound – formed by Ionic Bonding e.g. NaCl, MgSO4
    b) Covalent Compound – formed by Covalent Bonding e.g. Water, Carbon Dioxide

    Hope this helps.

  44. You are absolutely spot on!

    1 mol contains (6*10^23) NaCl ionic compounds.

    Since NaCl consists of 2 atoms, Na and Cl atom,

    Therefore total no. of atoms = (6*10^23)(1)(2)

    Cheers

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