Table of Contents
What does the number 12 in carbon-12 indicate?
The 12 in carbon-12 is the mass number of the isotope. This means that all atoms of carbon-12 have a mass of 12 atomic mass units.
What does the 6 mean in carbon-12?
The element carbon (C) has an atomic number of 6, which means that all neutral carbon atoms contain 6 protons and 6 electrons. The isotope of carbon that has 6 neutrons is therefore 126C. The subscript indicating the atomic number is actually redundant because the atomic symbol already uniquely specifies Z.
Why is carbon-12 used to define the mole?
as there are atoms in exactly 12 grams of carbon-12 (i.e., 6.022 X 1023). So the mole is the title used for the amount 6.022 x 1023 much the same way the word “dozen” is used for the amount 12. This means that the atomic mass or atomic weight (12 grams) of carbon is equal to exactly 1 mole of carbon.
What is meant by carbon-12 scale?
Definition of carbon 12 : an isotope of carbon of mass number 12 that is the most abundant carbon isotope and is used as a standard for measurements of atomic weight.
What is the carbon-12 scale?
Atomic mass is based on a relative scale and the mass of 12C (carbon twelve) is defined as 12 amu; so, this is an exact number. Each carbon atom has the same number of protons and electrons, 6. 12C has 6 neutrons, 13C has 7 neutrons, and 14C has 8 neutrons and so on.
How is carbon-12 formed?
The answer comes in the form of a reaction involving three helium nuclei, also known as alpha particles. At low temperatures, when the energy is not enough to reach the resonances, carbon-12 can still be formed through the simultaneous fusion of three alpha particles.
Why carbon-12 is a standard reference?
Carbon-12 is the standard while measuring the atomic masses. Because no other nuclides other than carbon-12 have exactly whole-number masses in this scale.
What is the mass of carbon-12?
| Click symbol for equation | |
|---|---|
| molar mass of carbon-12 | |
| Numerical value | 11.999 999 9958 x 10-3 kg mol-1 |
| Standard uncertainty | 0.000 000 0036 x 10-3 kg mol-1 |
| Relative standard uncertainty | 3.0 x 10-10 |
What is the function of carbon-12?
Carbon-12 is of particular importance in its use as the standard from which atomic masses of all nuclides are measured, thus, its atomic mass is exactly 12 daltons by definition.