What is the atomic mass of hydrogen Class 9?

Question 1 How is the size of an atom indicated?

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Atomic Mass of an Element
Table of Content
What is the Atomic Mass of Elements?
Atomic Mass of First 30 Elements

Question 2 Define atomic mass unit?

Question 3 What is the mass of hydrogen atom?

Question 4 Name the element used as a standard for atomic mass scale?

Atomic Mass of an Element

Actual masses of the atoms of the elements are very very small.

For Example : The atom of hydrogen has a mass of 1.6727 x 10-27 kg. It is not convenient to use such small and complicated figures in our calculation,therefore ,it was necessary to define atomic masses in such a way that we get simple figures for them.

Carbon-12 is that atom of carbon which has 6 protons and 6 neutrons in its nucleus so that so its mass number is 12.

carbon-12 atom has been assigned an atomic mass of exactly 12 atomic mass units.This means that a carbon-12 atom has been assigned an atomic mass of exactly 12u.

Atomic Mass unit = the mass of a carbon – 12 atom

One Atomic Unit is defined as exactly one-twelfth the mass of an atom of carbon-12.

Carbon-12 atom is taken to be the standard.The atomic masses of all other elements are determined by comparing the mass of their atom with the mass of a carbon-12 atom.

The atomic mass of an element is relative mass of its atom as compared with the mass of a carbon-12 atom taken as 12 units.

The atomic mass of elements is measured with the help of unified atomic mass units. One unified atomic mass unit can be quantified as the weight of one-twelfth of the mass of a carbon-12 atom considering that it is at rest. Since protons and neutrons account for almost all of the mass of the given atom, the atomic mass of a given element is almost equal to its mass number.

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What is the Atomic Mass of Elements?

The atomic mass of an element can be described as

the total mass of one atom of the given element. Its unit is called the unified atomic mass unit and is denoted by the symbol ‘u’.

Standard atomic weight is used to give the value of the mean of the atomic masses in a mixture of isotopes in a given sample of an element.

Atomic Mass of First 30 Elements

Given below is a table that lists the first 30 elements based on atomic number and their corresponding atomic mass.

ATOMIC NUMBER	ELEMENT	ATOMIC MASS
1	Hydrogen	1.008
2	Helium	4.0026
3	Lithium	6.94
4	Beryllium	9.0122
5	Boron	10.81
6	Carbon	12.011
7	Nitrogen	14.007
8	Oxygen	15.999
9	Fluorine	18.998
10	Neon	20.180
11	Sodium	22.990
12	Magnesium	24.305
13	Aluminium	26.982
14	Silicon	28.085
15	Phosphorus	30.974
16	Sulfur	32.06
17	Chlorine	35.45
18	Argon	39.948
19	Potassium	39.098
20	Calcium	40.078
21	Scandium	44.956
22	Titanium	47.867
23	Vanadium	50.942
24	Chromium	51.996
25	Manganese	54.938
26	Iron	55.845
27	Cobalt	58.933
28	Nickel	58.693
29	Copper	63.546
30	Zinc	65.38

The Molecular mass of an element can be calculated by adding the atomic masses of each of its constituents. There are many ways to find the atomic mass of an element, but the easiest way is to look it up on the periodic table of elements.

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View Quiz Answers and Analysis

One Mole of a substance is defined as the total number of atoms in 12 grams of Carbon-12 isotope. It is denoted by ‘mol’ and is also referred to as gram molecular weight.

Atomic mass is the average mass of the protons, neutrons, and electrons in an atom. Its unit is a unified atomic mass and is denoted by the symbol ‘u’.

An Atomic mass unit or one amu is the mass unit equivalent to the one-twelfth mass of one atom of the carbon-12 isotope.

Carbon-12 was chosen as a reference element for calculating atomic mass because it is naturally occurring and is present in abundance.

An Atomic mass unit or one amu is the physical constant accepted in the SI measurement system.