Atomic Mass of Elements

What Is An Atom?

“The smallest unit in the element that contains all the chemical properties in it”

Parts of atoms:

A current model of atom can split into three constituents parts and each part is associated with a charge:

Protons that carry positive charge
Electrons that carry negative charge
Neutrons that carry no net charge

According to the Standard Model of particle physics, protons and neutrons are present in the nucleus of the atom, while electrons revolve around the nucleus.

The electron configuration of an element explains how electrons are available in the atomic number of an atom. Whether you have multiple electrons in an atom, you can determine with the help of an electron configuration calculator.

What is the atomic mass of elements?

The atomic mass of a given element can be defined as:

“The average mass of the atoms of a given element measured in the unified atomic mass unit (amu) is known as the atomic mass of an element”

It is denoted by the symbol ‘u’.

Unified atomic mass unit (amu)

Generally, one unified atomic mass unit can be evaluated as the weight of one-twelfth of the mass of a carbon-12 atom considered at rest which is also referred as relative atomic mass of elemente. Atomic masses of elements are equal to their mass number, since protons and neutrons have the same for all the mass for a given atom.

How to calculate the atomic mass no of elements?

Standard atomic mass is determined by the average weight of all the isotopes of a given sample element. The average atomic mass of elements can be calculated by the abundance of each isotope multiplied by the mass number of elements.

For example:

Consider the gas neon, since it has three isotopes:

Neon-20:

It has ten protons and ten neutrons in its nucleus. Therefore, the atomic mass unit of the neon gas is 19.992, and the abundance of the gas is 90.48%.

Neon-21:

It has ten protons and eleven neutrons in its nucleus. Therefore the atomic mass unit of the neon gas is 20.994, and the abundance of the gas is 0.27%.

Neon-22:

It has ten protons and twelve neutrons in its nucleus. The atomic mass unit of the neon gas is 21.991, and the abundance of the gas is 9.25%.

To calculate the atomic mass of neon, the average of the isotopes is required to be taken out:

0.9048 × 19.992 = 18.09 amu

0.0027 × 20.994 = 0.057 amu

0.0925 × 21.991 = 2.03 amu

Then, add all values

18.09 + 0.057 + 2.03 = 20.18

The average atomic mass is thus: 20.18 amu

The atomic mass of first 30 elements

Let’s discuss the atomic mass of elements 1 to 30 in the periodic table. Here you can also find out the atomic mass of first 20 elements with the help of the atomic mass calculator. Given below is an atomic mass table that lists that is based on atomic number and their corresponding atomic mass of all elements.

ELEMENT

ATOMIC MASS

Hydrogen

1.008

Helium

4.0026

Lithium

6.94

Beryllium

9.0122

Boron

10.81

Carbon

12.011

Nitrogen

14.007

Oxygen

15.999

Fluorine

18.998

Neon

20.180

Sodium

22.990

Magnesium

24.305

Aluminium

26.982

Silicon

28.085

Phosphorus

30.974

Sulfur

32.06

Chlorine

35.45

Argon

39.948

Potassium

39.098

Calcium

40.078

Scandium

44.956

Titanium

47.867

Vanadium

50.942

Chromium

51.996

Manganese

54.938

Iron

55.845

Cobalt

58.933

Nickel

58.693

Copper

63.546

Zinc

65.38

Now, let us discuss atomic numbers and isotopes to clarify the above example.

Atomic number

An atomic number of an element can be defined as:

“Number of protons in a neutral atom which is equal to number electrons”

Example:

An atom of chlorine has 17 protons in its nucleus; hence, the atomic number of chlorine is 17. And, atomic mass of elements is equal to 35.45 of chlorine.

First 30 elements with atomic number

Let’s discuss the atomic number 1 to 30 in the periodic table. Look at the given table and describe the atomic number of elements from 1 to 30.