Atomic Mass

The atomic mass of an element is the average mass of the atoms in an element, calculated in Atomic Mass Units (amu) or Daltons. Unified atomic mass units are used to measure the atomic mass of elements. In terms of weight, one unified atomic mass unit is equal to one-twelfth of the mass of a Carbon-12 atom when it is at rest. The atomic mass of a given element is almost equal to its mass number since protons and neutrons make up almost all of the mass of the given atom. The atomic mass is also used in the classification of different isotopes of the same element, e.g. in the case of isotopes of hydrogen, Carbon, neon, etc.

What is Atomic Mass?

Atomic mass of an element is defined as the total mass of one atom of that element. The average mass of an element’s atoms expressed in atomic mass units is known as its atomic mass (amu, also known as daltons, D). The atomic number can also be called by the terms atomic weight.

The mass of each isotope is multiplied by its abundance to produce the relative atomic mass, which is a weighted average of all the isotopes of that element. For example, one Carbon atom has just six protons and typically six neutrons in its nucleus, thus its atomic mass should be roughly 12 amu.

Atomic mass units were created based on the masses of protons and neutrons. This is much simpler than stating that a proton or neutron weighs 1/167000000000000000000000th of a gram. Perhaps smaller than electrons, protons have a mass that is 1,836 times more than that of an electron.

List of Atomic Mass of First 30 Elements

Here is the table showing the first 30 elements of the periodic table with their atomic masses and atomic number:

Atomic Number	Elements	Symbol	Atomic Mass (in amu)
1	Hydrogen	H	1.008
2	Helium	He	4.0026
3	Lithium	Li	6.94
4	Beryllium	Be	9.0122
5	Boron	B	10.81
6	Carbon	C	12.011
7	Nitrogen	N	14.007
8	Oxygen	O	15.999
9	Fluorine	F	18.998
10	Neon	Ne	20.18
11	Sodium	Na	22.99
12	Magnesium	Mg	24.305
13	Aluminium	Al	26.982
14	Silicon	Si	28.085
15	Phosphorus	P	30.974
16	Sulfur	S	32.06
17	Chlorine	Cl	35.45
18	Argon	Ar	39.948
19	Potassium	K	39.098
20	Calcium	Ca	40.078
21	Scandium	Sc	44.956
22	Titanium	Ti	47.867
23	Vanadium	V	50.942
24	Chromium	Cr	51.996
25	Manganese	Mn	54.938
26	Iron	Fe	55.845
27	Cobalt	Co	58.933
28	Nickel	Ni	58.693
29	Copper	Cu	63.546
30	Zinc	Zn	65.38

Atomic Number

An element’s atomic number is determined by how many protons are found in one of its atoms. Each atom in an element has precisely the same number of protons. For instance, the atomic number of carbon is “6” since all carbon atoms have six protons.

Regardless of the presence of neutrons, elements are classified according to the number of protons in their nuclei. Uncharged subatomic particles known as neutrons are stable when contained in an atomic nucleus. Except for hydrogen, all other elements’ atoms have neutrons in the nucleus. Hence,

Atomic Number = Number of Protons in an atom

Mass Number

The total number of protons and neutrons in an atom’s nucleus is known as the mass number. Consequently, an atom of carbon will have an exact mass of 12 if its nucleus contains 6 protons and 6 neutrons.

The difference between the mass number and the atomic mass of an element is that a mass number is a whole number obtained by the addition of a number of protons and neutrons. While the atomic mass or atomic weight is the average number of protons and neutrons in an element for all of its isotopes.

The formula below can be used to determine the mass number of an atom of a specific element when looking at the periodic table of elements:

Mass Number = Number of Protons + Number of Neutrons

How to calculate the Atomic Mass?

Here are three ways to determine the Atomic Mass, depending on the given conditions:

By looking up to the atomic mass on the periodic table- In the periodic table digit of an atomic mass is usually marked under the representation of an element. Like Hydrogen 1u, Helium 3u.
Adding the Mass of Protons and Neutrons – The total number of protons and neutrons in an atomic nucleus gives the mass number.
Weighted Average for All Atoms of an Element – The weighted average of each element’s isotopes, grounded in nature by their abundance, is the atomic weight of that element. These recommendations can be used to calculate the atomic mass of the component. A list of isotopes with natural abundance and mass is given a percentage or decimal value. Each isotope’s abundance is multiplied by its mass. Divide the solution by 100 and add the findings if isotope abundance is present.

Molecular Mass

The atomic masses of the constituent atoms that make up a compound are added to determine its molecular mass.

The mass a molecule carries is known as its molecular mass, additionally known as molecular weight. It can be computed by summing the masses of all the atoms in the molecule and multiplying the result by the number of the element’s atoms. One oxygen atom and two hydrogen atoms, for instance, make up water. A water molecule’s mass is determined by multiplying its average hydrogen atomic mass by two and adding its average oxygen atomic mass. The atoms that make up the molecule are what define an element’s molecular mass.

FAQs based on Atomic Mass of Elements

Question 1: What is atomic mass?

Answer:

The mass of a single atom in a chemical element is known as its atomic mass. It involves the masses of protons, neutrons, and electrons, the three atomic subatomic particles.

Question 2: What is the significance of atomic mass?

Answers:

The fundamental physical property of matter is mass. The atomic mass refers to the mass of an atom or a molecule. The atomic mass is used to determine the average mass of atoms and molecules as well as to solve stoichiometry problems.

Question 3: What is one amu?

Answer: