What does it mean to have a relative atomic mass?

Since the actual mass of atoms is very small, it would be very troublesome to calculate them by their actual mass, for example, the actual mass of a hydrogen atom is kilograms, and the mass of an oxygen atom is kilograms. The mass of one carbon-12 atom is kilograms.

The relative atomic mass of an element is the weighted average of the relative atomic mass of its various isotopes. The lowest number in the periodic table is the relative atomic mass.

Definition: Relative atomic mass (AR) refers to the ratio of the average atomic mass of any atom to the mass of a carbon-12 atom 1 12 using the average atomic mass of any one as the standard of 1 12 of the atomic mass of a carbon-12 is called the relative atomic mass of the atom.

Features: When we calculate what is the mass of a water molecule, we find it extremely inconvenient to calculate. This is even more cumbersome when calculating the mass of other, more complex molecules.

Therefore, it is internationally stipulated that the relative atomic mass and relative molecular mass are used to express the mass relationship between atoms and molecules.

Taking one-twelfth of a carbon atom as the standard, the ratio of the mass of other atoms to it is called the relative atomic mass.

In layman's terms, it is one-twelfth divided by one carbon

That is, for one-twelfth of a certain carbon element, it is a standard (in fact, one) relative to other elements.

The ratio of this "1" is the relative atomic mass.

The mass of an element's atom is compared to the mass of a carbon atom 1 12, and the resulting ratio is the relative atomic mass of this atom.

An element may have multiple isotopes, and the proportion of each isotope is different, and the average atomic mass is calculated according to the mass and proportion of the isotope.

There are many isotopes of carbon, such as C12, C13, etc., and we choose one carbon atom as the reference.

The relative atomic mass, then, is the ratio of the average atomic mass of an element to the atomic mass of a carbon 1 12.

The relative number of atoms is approximately equal to the number of protons plus the number of neutrons... This is approximately equal to the mass number.

Relative atomic weight refers to the ratio of the average atomic mass of an element to the atomic mass of nuclide c (carbon)12 12.

The relative atomic mass is the ratio of the atomic mass of an element to the mass of a carbon-12 atom.

The relative atomic mass of common atoms is something to keep in mind, for example, the relative atomic mass of h is 1, and the relative atomic mass of o is 16.

Relative atomic Mass = Atomic Mass of a carbon atom (1 12), e.g. the atomic mass of h is , the atomic mass of c is , then the relative atomic mass of h is , note that there is no decimal in the relative atomic mass, only an integer.

Relative atomic mass refers to the meaning of atomic weight.

It refers to the ratio of the true mass of any atom to the mass of a carbon-12 atom of 1 12 using 1 12 of the atomic mass of a carbon-12 as the standard.

The atomic weight of an element is the weighted average of the relative atomic masses of its various isotopes, and the lowest number in the periodic table is the atomic weight. Bu Qilu.

The atomic weight was first proposed by the British scientist Dalton. "Atoms of the same element have the same weight, and atoms of different elements have different weights," he said. Therefore, atomic weight is translated as "atomic weight" in Chinese.

However, at that time, since weight and mass were the same concept, the relative mass of the atom was actually obtained, but it was still called atomic weight.

International Regulations:

The carbon atom divides the mass of a carbon-12 atom into 12 equal parts, (there are several kinds of carbon atoms, among which there is a carbon atom that contains 6 protons and 6 neutrons in its nucleus, which adds up to 12, so it is called carbon-12.) Of course, there are others, such as positive carbon-14, which contains 8 neutrons and 6 protons, which add up to 14.

The reason why carbon-12 is chosen instead of carbon-14 is that when carbon-12 atoms are selected as the standard, the relative atomic masses of other atoms are close to integers, which is easy to remember and use). Then the mass of each part is: the mass of an atom (1 12 the mass of a carbon-12 atom) = the mass of an atom.

Categories: Education, Science, >> Science & Technology.

Analysis: The mass of an atom is expressed in the unit of mass "kilogram", which is extremely inconvenient for writing, memorization, and use. Because of this, the mass of an atom is not scientifically expressed in "kilograms".

Rather, the mass of a carbon atom is 1 12 kilograms, and the relative atomic mass (atomic weight) of the atom is compared with the mass of other atoms.

From the above calculations, it can be seen that the relative atomic mass is a relative ratio.

A carbon atom is a carbon atom with 6 protons and 6 neutrons in its nucleus, commonly known as a carbon-12 atom.

Information. The International Atomic Weight Commission adopted Zhang Qinglian, an academician of the Chinese Academy of Sciences, and determined the relative atomic mass of indium as a new standard.

The positive argument of the relative atomic mass of a chemical element is an important natural constant. For two centuries, the determination of the relative atomic mass of the standard has been contributed by the advanced countries.

Chinese chemist Zhang Qinglian and Xiao Yingkai of the Chinese Academy of Sciences cooperated to accurately determine the relative atomic mass of indium (in) by Chazheng mass spectrometry, which was determined by the International Atomic Weight Commission at the Hamburg meeting in August 1991 as the new standard relative atomic mass.