1 To 20 Atomic Number

The elements of the periodic table sorted by atomic number

First 10 Periodic Table
Atomic Number For Elements
1 To 20 Atomic Number Element

The atomic number. Of an element tells you how many protons that the element has. This is written at the bottom left hand side of the symbol. (only true for the first 20 elements). This is a list of the 118 chemical elements which have been identified as of 2021. A chemical element, often simply called an element, is a species of atoms which all have the same number of protons in their atomic nuclei (i.e., the same atomic number, or Z). Study Flashcards On Periodic Table Elements by atomic number (1-20) at Cram.com. Quickly memorize the terms, phrases and much more. Cram.com makes it easy to get the grade you want! Point to the graph to see details, or click for full data on that element.

click on any elements name for further chemical properties, environmental data or health effects.

This list contains the 118 elements of chemistry.

The chemical elements of the periodic chart sorted by:	Atomic number	Name chemical element	Symbol
- Name alphabetically	1	Hydrogen	H
- Atomic number	2	Helium	He
- Symbol	3	Lithium	Li
- Atomic Mass	4	Beryllium	Be
- Electronegativity	5	Boron	B
- Density	6	Carbon	C
- Melting point	7	Nitrogen	N
- Boiling point	8	Oxygen	O
- Vanderwaals radius	9	Fluorine	F
- Year of discovery	10	Neon	Ne
- Inventor surname	11	Sodium	Na
- Elements in earthcrust	12	Magnesium	Mg
- Elements in human body	13	Aluminum	Al
- Covalenz radius	14	Silicon	Si
- Ionization energy	15	Phosphorus	P
For chemistry students and teachers: The tabular chart on the right is arranged by Atomic number. The first chemical element is Hydrogen and the last is Ununoctium. Please note that the elements do not show their natural relation towards each other as in the Periodic system. There you can find the metals, semi-conductor(s), non-metal(s), inert noble gas(ses), Halogens, Lanthanoides, Actinoids (rare earth elements) and transition metals.	16	Sulfur	S
	17	Chlorine	Cl
	18	Argon	Ar
	19	Potassium	K
	20	Calcium	Ca
	21	Scandium	Sc
	22	Titanium	Ti
	23	Vanadium	V
	24	Chromium	Cr
	25	Manganese	Mn
	26	Iron	Fe
	27	Cobalt	Co
	28	Nickel	Ni
	29	Copper	Cu
	30	Zinc	Zn
	31	Gallium	Ga
	32	Germanium	Ge
	33	Arsenic	As
	34	Selenium	Se
	35	Bromine	Br
	36	Krypton	Kr
37	Rubidium	Rb
38	Strontium	Sr
39	Yttrium	Y
40	Zirconium	Zr
41	Niobium	Nb
42	Molybdenum	Mo
43	Technetium	Tc
44	Ruthenium	Ru
45	Rhodium	Rh
46	Palladium	Pd
47	Silver	Ag
48	Cadmium	Cd
49	Indium	In
50	Tin	Sn
51	Antimony	Sb
52	Tellurium	Te
53	Iodine	I
54	Xenon	Xe
55	Cesium	Cs
56	Barium	Ba
57	Lanthanum	La
58	Cerium	Ce
59	Praseodymium	Pr
60	Neodymium	Nd
61	Promethium	Pm
62	Samarium	Sm
63	Europium	Eu
64	Gadolinium	Gd
65	Terbium	Tb
66	Dysprosium	Dy
67	Holmium	Ho
68	Erbium	Er
69	Thulium	Tm
70	Ytterbium	Yb
71	Lutetium	Lu
72	Hafnium	Hf
73	Tantalum	Ta
74	Tungsten	W
75	Rhenium	Re
76	Osmium	Os
77	Iridium	Ir
78	Platinum	Pt
79	Gold	Au
80	Mercury	Hg
81	Thallium	Tl
82	Lead	Pb
83	Bismuth	Bi
84	Polonium	Po
85	Astatine	At
86	Radon	Rn
87	Francium	Fr
88	Radium	Ra
89	Actinium	Ac
90	Thorium	Th
91	Protactinium	Pa
92	Uranium	U
93	Neptunium	Np
94	Plutonium	Pu
95	Americium	Am
96	Curium	Cm
97	Berkelium	Bk
98	Californium	Cf
99	Einsteinium	Es
100	Fermium	Fm
101	Mendelevium	Md
102	Nobelium	No
103	Lawrencium	Lr
104	Rutherfordium	Rf
105	Dubnium	Db
106	Seaborgium	Sg
107	Bohrium	Bh
108	Hassium	Hs
109	Meitnerium	Mt
110	Darmstadtium	Ds
111	Roentgenium	Rg
112	Copernicium	Cn
113	Nihonium	Nh
114	Flerovium	Fl
115	Moscovium	Mc
116	Livermorium	Lv
117	Tennessine	Ts
118	Oganesson	Og

First 10 Periodic Table

Click here: for a schematic overview of the periodic table of elements in chart form

Do you need to know the weight of some molecules? Try our Molecular Weight Calculator!

Please report any accidental mistake in the above statistics on chemical elements

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Contents

Atomic number and Mass number
Isotopes

Atom

An atom is the smallest particle of an element which can take part in chemical reaction. Atom consists of three fundamental particles i.e. proton, neutron and electron. Atoms of same elements are similar in properties whereas atoms of different elements are different in properties. Example:- ‘H’ represent the atom of hydrogen.

Proton is positively charged and electron is negatively charged particle. In an atom, number of protons = number of electrons. Hence, the net charge present in an atom is zero i.e. a free atom is chargeless.

Atomic number and Mass number

Atomic number :

Atomic number is the number of protons present in an atom.
The modern periodic table is arranged in order of increasing atomic number.

Mass number and Atomic mass :

Mass number is the sum of the number of protons and the number of neutrons present in an atom. It is a whole number.

Mass no. of an atom = No. of protons + No. of neutrons

Atomic mass is the average mass of the all of the isotopes of that element. It is a decimal number.
For example: Hydrogen has three isotopes – ₁H¹, ₁H² and ₁H³ having mass number 1, 2 and 3 respectively. Naturally occurring hydrogen contains about 99.985% of protium, 0.014% of deuterium and 0.001 % of tritium. Therefore the atomic mass of hydrogen is 1.00784 amu.
The atomic mass of an element element is measured in atomic mass unit (amu, also known as Daltons ‘ D’or unified atomic mass unit ‘u’).
1amu = 1.66 x 10^-24 grams. 1gm = 6.022 x 10²³ amu ( i.e. Avogadro’s number).

Here,

Atomic number = Number of protons = Number of electrons = 13
Mass number = No. of protons + No. of neutrons
No. of neutrons = Mass number – No. of protons = 27-13 = 14.

Atomic mass of first 20 elements

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

Isotopes

Atoms of the same element having same atomic number but different mass number (atomic mass/weight) are called isotopes. For example:

Isotopes of hydrogen :

There are three isotopes of hydrogen:

Protium or ordinary hydrogen
Deuterium or heavy hydrogen
Tritium or radioactive hydrogen.

Name	Protium	Deuterium	Tritium
Symbol	¹H or H	²H or D	³H or T
No. of protons(P)	1	1	1
No. of neutrons(n)	0	1	2
No. of electrons(e)	1	1	1
Atomic no.(Z)	1	1	1
Mass no.(A)	1	2	3

Naturally occurring hydrogen contains about 99.985% of protium, 0.014% of deuterium and 0.001 % of tritium.

Isotopes have different physical properties since they differ in their mass number.

They have same chemical properties since their electronic configuration is same. However, they differ in the rate of chemical reaction. For example, D₂ reacts with Cl₂ about 13 times slower than H₂ does. The different in rate of reaction due to difference in mass of the atoms of the same element is called isotope effect.

Some other examples of isotopic elements :

Elements	Isotopes	Most abundant isotope
Carbon	₆C¹², ₆C¹³, ₆C¹⁴	₆C¹²
Nitrogen	₇N¹⁴, ₇N¹⁵	₇N¹⁴
Oxygen	₈O¹⁶, ₈O¹⁷, ₈O¹⁸	₈O¹⁶
Sulphur	₁₆S³², ₁₆S³³, ₁₆S³⁴, ₁₆S³⁶	₁₆S³²
Chlorine	₁₇Cl³⁵, ₁₇S³⁷	₁₇Cl³⁵

Isobars

Atoms of different elements having different atomic number but same mass number are called isobars. For example :

₁₈Ar⁴⁰, ₁₉K⁴⁰ and ₂₀Ca⁴⁰

Isotones

Atoms of different elements having different atomic number and mass number but same number of neutrons are called isotones. For example :

₆C¹⁴, ₇N¹⁵ and ₈O¹⁶

Objective questions and their answers

1. Which of the following is known as heavy hydrogen?

a. Protium c. Tritium

b. Deuterium d. Para hydrogen

2. Which of the following is known as radioactive hydrogen?

a. Protium c. Tritium

b. Deuterium d. Para hydrogen

3. Least abundant isotope of hydrogen is:

a. Protium c. Tritium

b. Deuterium d. Heavy hydrogen

4. Diamond and graphite are :

a. Isotopes c. Isotones

b. Isobars d. Allotropes

5. ₆C¹⁴ and ₈O¹⁶are :

a. Isotopes c. Isotones

b. Isobars d. Allotropes

6. ₆C¹⁴ and ₇N¹⁴ are :

a. Isotopes c. Isotones

b. Isobars d. Allotropes

7. All particles residing inside the nucleus of an atom are termed as:

a. Protons c. Electrons

b. Neutrons d. Nucleons

8. What makes the atomic mass fractional ?

a.Prerence of isotopes

b. Number of unpaired electrons

c. Spherical shape

d. Quantum number.

9. Which of the following are not isotopes:

a. ₁H¹ and ₁H³

b.₁₈K⁴⁰ and ₂₀Ca⁴⁰

c.₆C¹⁴ and ₇N¹⁴

d. Both b and c.

10. Charge present in the nucleus of an atom is :

Atomic Number For Elements

a. Positive c. Chargeless

b. Negative d. Both +Ve and -Ve

11. Molecular weight of heavy water is :

a. 16 c. 20

b. 18 d. 22

Answers :

1. b 2. c 3. c