Help needed badly in understanding the concept of atomic masses

  • Thread starter Thread starter mathzeroh
  • Start date Start date
  • Tags Tags
    Atomic Concept
Click For Summary

Discussion Overview

The discussion revolves around the concept of atomic masses, specifically addressing the roles of protons, neutrons, and electrons in determining the mass of an atom. Participants explore foundational questions related to atomic structure and isotopes, as well as the implications of mass numbers.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the assertion that neutrons determine the mass of an element, citing confusion over the mass of hydrogen and its isotopes.
  • Another participant clarifies that hydrogen has no neutrons, with deuterium and tritium being its isotopes, and provides specific atomic mass values for hydrogen and its components.
  • Some participants argue that atomic mass is determined by the sum of protons, neutrons, and electrons, challenging the notion that neutrons alone dictate mass.
  • There is a suggestion that the average atomic mass of hydrogen reflects the rarity of its isotopes, which influences the reported mass value.
  • One participant emphasizes the contribution of electrons to atomic mass, albeit minor compared to protons and neutrons.
  • A later reply introduces the classification of protons and neutrons as hadrons, contrasting them with electrons as leptons, which adds a layer of complexity to the discussion.
  • The original poster expresses gratitude for the clarifications but raises additional questions about the arrangement of protons and neutrons in the nucleus and seeks resources for further understanding.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the role of neutrons in determining atomic mass, with multiple competing views presented regarding the contributions of protons, neutrons, and electrons. The discussion remains unresolved on certain foundational concepts.

Contextual Notes

Some statements made by participants reflect differing interpretations of atomic mass and the roles of subatomic particles, indicating a need for clarity on definitions and concepts. The discussion includes references to specific atomic mass values that may vary by source.

mathzeroh
Messages
98
Reaction score
0
i hope everyone's in fine health in this fine thursday evening. :approve:

ok i just had some general questions on atomic masses, and to the chemists in here, i appologize if these questions are a bit too basic for you. :cry: but ur help and time is greatly appreciated nonetheless! :smile:

so here are my questions (these are based on readings I've come across in the textbook):

Why is it that the number of neutrons determine the mass of an element? I ask this because to me, this idea doesn't fit completely altogether because an isotope is identified by its mass number, A, the total number of protons and neutrons in the nucleus.

mass number (A) = number of protons (Z) + number of neutrons

Even for Hydrogen, on periodic tables, it's stated that hydrogen has 1.0078 amu, but this isn't right according to the rule of "the number of neutrons determine the mass of an element," because one Neutron has the following mass:

neutron = 1.00867 amu

and that doesn't at all look anything like 1.0078 amu. so what i did was i added the weight of ONE proton which is 1.00728 amu (looks a lot closer to the actual mass of H :rolleyes: ) and then divided by two (for reasons unknown, or not that clear to myself). that gave me this:

1.007975

what do i do?? :cry: :cry: :cry: :confused:

(thanks in advance for the help and your time!)
 
Last edited:
Chemistry news on Phys.org
No neutrons in hydrogen, 1 neutron is deuterium, 2 neutrons is tritium. The amu of hydrogen ( in my textbooks) is 1.0079. The amu of a proton is 1.0073 the amu of an electron is .00055, so the hydorgen amu is 1.0079.
 
And at add to that, whatever book said that neutrons determine the atomic mass is horribly inaccurate. Nothing by itself determines what the atomic mass is. Its all the electrons + the protons + the neutrons which will equal the atomic mass. Dont let it fool you, its still a basic mass. Its like adding dumbells together. Wanna find the weight of a 'system' of 3 dumb bells, you find hte masses of each dumb bell and add them all together.
 
mathzeroh said:
mass number (A) = number of protons (Z) + number of neutrons
This is perfectly correct.

but this isn't right according to the rule of "the number of neutrons determine the mass of an element,"
This "rule" is wrong ! I'm not sure where you read or heard that, but it is not correct. The mass is determined by both protons and neutrons (as well as, to a much smaller extent, electrons).

The mass of the H-atom is the sum of the proton's and electron's masses.
 
Mass of a atom is the mass of the protones and neutrone not just neutrones.and mass of the hidrogen differs from this a little bit because its the average of the mass of all the hidrogen isotpes available.the value so close to the mass of H1 because deuterium and tritium are really rare.

If this doesn't solve youre question contact me
 
Mass of a atom is the mass of the protones and neutrone not just neutrones.and mass of the hidrogen differs from this a little bit because its the average of the mass of all the hidrogen isotpes available.the value so close to the mass of H1 because deuterium and tritium are really rare.

If this doesn't solve youre question contact me.feel free to contact me at
kusal.w@gmail.com
 
Oh and watch out guys, don't want to confuse this guy by forgetting electrons. Electrons do contribute to the mass but...

mass of proton: 1.6726 x 10 ^ -27 kg
mass of neutron: 1.6749 x 10 ^ -27 kg
mass of electron: 9.11 x 10 ^ -31 kg

So they don't really contribute when your dealing with that few digits... but they are still counted.
 
OHHHHH wow thanks a lot everybody! that cleared everything up, thanks a bunch!

but i had another question, why are the protons all packed on top of the neutrons in the neuclus and why do the electrons spin around them? that's one concept I've never understood really. is there a site where i can read a bit on it, i mean one that'll put it in simple terms? :) thanks again!
 
This is hardly a trivial question.

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html#c1

Another important distinction is that neutrons and protons belong to a class of particles known as hadrons, while electrons are member of another class known as leptons. This makes the protons and neutrons similar - in a fashion - to each other, and different from the electrons.

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/hadron.html#c5
http://hyperphysics.phy-astr.gsu.edu/hbase/particles/lepton.html#c1
 

Similar threads

Understanding atomic mass units (amu) and weight of particles
  • · Replies 2 ·
Replies
2
Views
4K
Why wasn't fluorine used as a standard for atomic mass?
  • · Replies 6 ·
Replies
6
Views
4K
Finding Atomic Mass Unit by Subatomic Particles
  • · Replies 1 ·
Replies
1
Views
1K
Doubts regarding Atomic mass,relative atomic mass and mass number.
  • · Replies 1 ·
Replies
1
Views
4K
High School Understanding Mass Excess and Atomic Mass in Nuclear Physics
  • · Replies 7 ·
Replies
7
Views
4K
Whether sum of weight of proton and neutron is equal to atomic mass?
  • · Replies 1 ·
Replies
1
Views
6K
Mass of ions with respect to amu
  • · Replies 1 ·
Replies
1
Views
7K
Atomic Mass Units: Discrepancy Explained?
  • · Replies 1 ·
Replies
1
Views
4K
Semi empirical mass formula derivation help
  • · Replies 4 ·
Replies
4
Views
2K
Chemical Amount: Hydrogen & Oxygen Ratio?
  • · Replies 2 ·
Replies
2
Views
5K