You are viewing the article How to Calculate Atomic Mass at Tnhelearning.edu.vn you can quickly access the necessary information in the table of contents of the article below.
Calculating atomic mass is a crucial step in understanding the characteristics and behaviors of elements in chemistry. Atomic mass, also known as atomic weight, refers to the average mass of an element’s atoms, taking into account the various isotopes and their relative abundances. It is a fundamental concept that aids in studying elements, their properties, and their reactions. By determining atomic mass accurately, scientists can accurately predict and understand the behavior of elements, aiding in fields such as medicine, materials science, and environmental studies. In this guide, we will explore the methods and formulas used to calculate atomic mass, providing you with a clear understanding of this essential concept in chemistry.
This article is co-authored by a team of editors and trained researchers who confirm the accuracy and completeness of the article.
The wikiHow Content Management team carefully monitors the work of editors to ensure that every article is up to a high standard of quality.
This article has been viewed 86,092 times.
Atomic mass is the total mass of protons, neutrons, and electrons in an atom or molecule. [1] X Research Source However, the mass of the electron is often ignored and not included in the formula because this value is very small. [2] X Research Source Atomic mass is often used to refer to the average atomic mass of all isotopes of an element, although such a usage is academically incorrect. The average atomic mass is actually the relative atomic mass, also known as the atomic weight , of an element. [3] X Research Source Atomic weight is determined based on the average mass of natural isotopes of the same element. Chemists need to distinguish these two types of atomic mass in their calculations, because taking the wrong atomic mass value can lead to errors when calculating the reaction efficiency.
Steps
Find the atomic mass on the periodic table
- The atomic mass unit indicates the mass of one mp of an element or molecule in grams . Therefore, this is a very useful property in practical calculations because it allows us to easily convert between the mass and the number of mps of a given number of atoms or molecules in the same state.
- It should be noted that the relative atomic mass given in the periodic table is the average mass of that element. Elements with multiple isotopes – isotopes are different variations of the same element and each has a different mass since they will have more or less one to a few neutrons in the nucleus of the element. atom. [5] X Source of study Therefore, the relative atomic mass given in the periodic table only represents the average mass of the atoms of an element, not the mass of an atom of that element. .
- Relative atomic mass, as stated in the periodic table, is used to calculate the mass mp of atoms and molecules. Technically, the atomic mass, when expressed in units of amu as shown in the periodic table, has no units. However, multiplying the atomic mass by 1g/mp yields a quantity that can be used to calculate the mass mp – the mass (in grams) of one mp of atoms – of an element.
- Since this is an average of many isotopes, the value given in the periodic table is not an exact atomic mass value for any one atom of that element.
- The atomic mass of individual atoms must be calculated by considering the exact number of protons and neutrons in each atom.
Calculate the atomic mass of a single atom
- Consider the carbon atom. Carbon always has 6 protons, so the atomic number of carbon is 6. We can also look in the periodic table, in the box for carbon (C), we have the number “6” above the chemical symbol (C). , which denotes that carbon’s atomic number is six.
- It should be noted that the atomic number of an element does not directly affect the relative atomic mass given in the periodic table. Although it may seem that the atomic mass of a substance is twice the atomic number of that substance, especially for elements at the top of the periodic table, it is not possible to calculate the atomic mass by doubling the atomic number. atom.
- The number of neutrons can be determined based on the isotopic indication of the element. For example, carbon 14 is a naturally occurring isotope of carbon-12. An isotope is indicated by a number written above the element symbol: 14 C. The number of neutrons is calculated by subtracting the number of protons from the isotope indicator: 14 – 6 = 8 protons.
- Suppose we are considering a carbon atom with 6 neutrons ( 12 C). It is the most common isotope of carbon, accounting for about 99% of the carbon atoms present in nature. [7] X Research Source However, 1% of carbon atoms contain 7 neutrons ( 13 C). Other forms of carbon with more or less than 6 or 7 neutrons exist only in very small quantities.
- The carbon atom has 6 protons + 6 neutrons = 12. The atomic mass of this carbon is 12. On the other hand, if it were the isotope carbon-13 , the atom would have 6 protons + 7 neutrons = 13 , in this case the atomic mass would be 13.
- The net atomic mass of carbon-13 is 13.003355 [8] X Research Source , this value is more accurate because it is determined experimentally.
- The atomic mass of an element is very close to the isotope indicator number. In simple calculations, we can treat the number of isotopic indicators as equal to the atomic mass. When determined experimentally, the atomic mass will be slightly larger than the isotope indicator number because at this time the very small mass of the electrons is also taken into account.
Calculate the relative atomic mass of an element
- For the purposes of this article, let’s assume we are dealing with isotopes of carbon-12 and carbon-13.
- The carbon-12 abundance is 99% and the carbon-13 abundance is 1%. Other isotopes of carbon do exist, but in very small amounts, so for this example we can ignore their values.
- In the example under consideration, the sample contains carbon-12 and carbon-13. If carbon-12 makes up 99% of the sample, and carbon-13 makes up 1% of the sample, multiply 12 (atomic mass of carbon-12) by 0.99 and multiply 13 (atomic mass of carbon-13) by 0, 01.
- Reference books will likely have percentage information based on known isotopes of an element. Most chemistry textbooks have a table of this data at the end of the book. The mass spectrometer can also give results on the ratio of isotopes in the sample.
- In our example, we have 12 x 0.99 = 11.88 with carbon-12 and 13 x 0.01 = 0.13 with carbon-13. So the relative atomic mass in this example is 11.88 + 0.13 = 12.01 .
Things you need
- Chemistry reference book
- Computer
This article is co-authored by a team of editors and trained researchers who confirm the accuracy and completeness of the article.
The wikiHow Content Management team carefully monitors the work of editors to ensure that every article is up to a high standard of quality.
This article has been viewed 86,092 times.
Atomic mass is the total mass of protons, neutrons, and electrons in an atom or molecule. [1] X Research Source However, the mass of the electron is often ignored and not included in the formula because this value is very small. [2] X Research Source Atomic mass is often used to refer to the average atomic mass of all isotopes of an element, although such a usage is academically incorrect. The average atomic mass is actually the relative atomic mass, also known as the atomic weight , of an element. [3] X Research Source Atomic weight is determined based on the average mass of natural isotopes of the same element. Chemists need to distinguish these two types of atomic mass in their calculations, because taking the wrong atomic mass value can lead to errors when calculating the reaction efficiency.
In conclusion, calculating atomic mass is a fundamental step in understanding and studying the properties of atoms. By considering the relative abundance and mass of various isotopes, scientists can determine the average atomic mass of an element. This calculation is crucial for many applications in chemistry, such as identifying unknown elements, balancing chemical equations, and predicting the behavior of substances. Additionally, atomic mass is a key concept in the development of periodic tables and the classification of elements. Overall, understanding how to calculate atomic mass is an essential skill for any student or researcher in the field of chemistry.
Thank you for reading this post How to Calculate Atomic Mass at Tnhelearning.edu.vn You can comment, see more related articles below and hope to help you with interesting information.
Related Search:
1. How to calculate atomic mass using the periodic table
2. Step-by-step guide for calculating atomic mass
3. What is atomic mass and why is it important?
4. Isotope abundance and its role in calculating atomic mass
5. How to find the atomic mass of an element with multiple isotopes
6. Atomic mass unit (amu) and its significance in atomic mass calculations
7. How atomic mass is determined experimentally
8. Understanding the relationship between atomic mass and molar mass
9. Calculating the average atomic mass of an element
10. Common mistakes to avoid when calculating atomic mass