0
Two sample of carbon have the same atomic number but different atomic masses Why do the two samples have different atomic number?
Wiki User
∙ 14y ago
ISOTOPE
The answer is that, first, different atoms of the same element will not have different atomic numbers because the identity of an element is determined by the number of protons in its nucleus. And the number of protons of an atom is its atomic number. Pick any atom of that element and it will have that unique number of protons. Elemental identity and proton count are inseparably linked. Said another way, all of the atoms of that element will have the same atomic number - the same number of protons. Electrons can come and go, being borrowed or loaned out in chemical activity, but the proton count remains constant for a given element. Now to the Atomic Mass.
It turns out that for a given atom (and that atom will have a fixed number of protons), the number of neutrons can vary. Said another way, the number of neutrons in any atom of a given element can be different from one atom of that element to another atom of that element. We say that a given element has different isotopes. It has its fixed number of protons, but the number of neutrons isn't fixed. Each isotope has that same characteristic number of protons, but the number of neutrons can vary from one atom to the next. Let's take an example.
Lithium has 3 protons in its nucleus. Every atom of lithium is like this. Its atomic number is three. Always. But what about neutrons? It turns out that there are two stable configurations possible. One has 3 neutrons. Its atomic mass is about 6.015 or so. Recall that subtracting the atomic number from the atomic mass gives us the number of neutrons in the nucleus of that atom. The 6.015 minus the 3 yields an answer of 3 for the number of neutrons. There is also a lithium atom that has 4 neutrons in its nucleus. Its atomic mass is about 7.016 or so. Same math. Take the 7.016 and subtract the 3 and get 4 as the answer - and the number of neutrons in the nucleus of that atom. Those are the two stable isotopes of lithium. (There are a number of other isotopes of lithium, but they're all unstable and disappear fairly quickly after being made in the physics lab.)
Pick any other element and it will have a unique identity based on the number of protons in the nucleus. But it will have different numbers of neutrons as you look around at different atoms of that element. The different numbers of neutrons account for the different atomic masses of given isotopes of that element.
Wiki User
∙ 14y ago
Wiki User
∙ 14y agoIf you mean why the two have a different atomic mass then, the reason for the difference between the atomic mass is because they are different isotopes. An example would be Carbon-12 has an atomic mass of 12 while Carbon-18 has an atomic mass of 18.
Wiki User
∙ 8y agoBecause they have same number of protons.If it change type of element also change
Add your answer:
Earn +20 pts
State the name and the mass of the isotope relative to which all atomic masses are measured?
Carbon-12 is used as the standard by which the atomic masses of other nuclides are measured.
What atoms with same atomic number but different atomic masses?
Isotopes of the same element have the same number of protons (atomic number) but differ in number of neutrons (hence atomic masses).
Are there any physical properties that differ between isotopes?
Atomic Masses are different So Boiling point, freezing points. inter-molecular forces, etc may be different as they depend on atomic masses
What is the difference between isotopes of the same element?
They have different numbers of neutrons. Due to a difference in number of neutrons, they also have different masses. For example, take the element carbon. Carbon could have six neutrons (12C) or eight neutrons (14C). Both 14C and 12C are isotopes of carbon and therefore have different masses.
What do you called in an element having the same atomic number but different atomic masses?
Isotopes. eg U235 and U238. Both Uranium, atomic number 92, bur different isotopes.
Which refers to atoms with the same atomic number but different atomic masses?
They are called isotopes. eg we have different isotopes of carbon
What atom is standard for atomic masses?
Carbon (12).
What element are atomic masses of all element based on?
carbon
Do carbon 12 and 14 have the same atomic mass?
No. They have different masses, but the same atomic number. Carbon-12 has a mass number of 12 and atomic number of 6, and carbon-14 has a mass number of 14 and atomic number of 6. The difference in mass number is due to different numbers of neutrons. Carbon-12 atoms have 6 neutrons and carbon-14 atoms have 8 neutrons.
What nuclide is used as the standard in the relative scale for atomic masses and What is it's assigned atomic mass?
Carbon 12
Atoms having the same atomic number but different atomic masses?
Isotopes
State the name and the mass of the isotope relative to which all atomic masses are measured?
Carbon-12 is used as the standard by which the atomic masses of other nuclides are measured.
Do all elements have different atomic masses?
yes
Isotopes of the same element have different .?
atomic masses
Why are gram formula masses called relative masses?
They are called relative masses because all of the masses of the elements are measured relative to the mass of an isotope of carbon called carbon-12. Carbon-12 has been assigned a mass of exactly 12 atomic mass units. One atomic mass unit has an actual value of 1.660538782(83)×10^−27 kg.
What nuclide is used as standard relative scale for atomic masses?
12 grams of carbon-12 isotope.
What do you call atoms of the same element with different atomic masses?
They are called isotopes. They have different mass nmbers because they have a different number of neutrons.
