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• Calcium, a chemical element with the symbol Ca and atomic number 20, is a reactive metal that can form a dark oxide-nitrite layer when exposed to the atmosphere.It is the third most abundant metal on the earth's surface after iron and aluminum.
• Calcium The chemical element Calcium (Ca), atomic number 20, is the fifth element and the third most abundant metal in the earth’s crust. The metal is trimorphic, harder than sodium, but softer than aluminium. A well as berylliumand aluminium, and unlike the alkaline metals, it doesn’t cause skin-burns.

No.		Atomic weight	Name	Sym.	M.P. (°C)	B.P. (°C)	Density* (g/cm3)	Earth crust (%)*	Discovery (Year)	Group*	Electron configuration	Ionization energy (eV)
1	1.008	Hydrogen	H	-259	-253	0.09	0.14	1776	1	1s1	13.60
2	4.003	Helium	He	-272	-269	0.18	1895	18	1s2	24.59
3	6.941	Lithium	Li	180	1,347	0.53	1817	1	[He] 2s1	5.39
4	9.012	Beryllium	Be	1,278	2,970	1.85	1797	2	[He] 2s2	9.32
5	10.811	Boron	B	2,300	2,550	2.34	1808	13	[He] 2s2 2p1	8.30
6	12.011	Carbon	C	3,500	4,827	2.26	0.09	ancient	14	[He] 2s2 2p2	11.26
7	14.007	Nitrogen	N	-210	-196	1.25	1772	15	[He] 2s2 2p3	14.53
8	15.999	Oxygen	O	-218	-183	1.43	46.71	1774	16	[He] 2s2 2p4	13.62
9	18.998	Fluorine	F	-220	-188	1.70	0.03	1886	17	[He] 2s2 2p5	17.42
10	20.180	Neon	Ne	-249	-246	0.90	1898	18	[He] 2s2 2p6	21.56
11	22.990	Sodium	Na	98	883	0.97	2.75	1807	1	[Ne] 3s1	5.14
12	24.305	Magnesium	Mg	639	1,090	1.74	2.08	1755	2	[Ne] 3s2	7.65
13	26.982	Aluminum	Al	660	2,467	2.70	8.07	1825	13	[Ne] 3s2 3p1	5.99
14	28.086	Silicon	Si	1,410	2,355	2.33	27.69	1824	14	[Ne] 3s2 3p2	8.15
15	30.974	Phosphorus	P	44	280	1.82	0.13	1669	15	[Ne] 3s2 3p3	10.49
16	32.065	Sulfur	S	113	445	2.07	0.05	ancient	16	[Ne] 3s2 3p4	10.36
17	35.453	Chlorine	Cl	-101	-35	3.21	0.05	1774	17	[Ne] 3s2 3p5	12.97
18	39.948	Argon	Ar	-189	-186	1.78	1894	18	[Ne] 3s2 3p6	15.76
19	39.098	Potassium	K	64	774	0.86	2.58	1807	1	[Ar] 4s1	4.34
20	40.078	Calcium	Ca	839	1,484	1.55	3.65	1808	2	[Ar] 4s2	6.11
21	44.956	Scandium	Sc	1,539	2,832	2.99	1879	3	[Ar] 3d1 4s2	6.56
22	47.867	Titanium	Ti	1,660	3,287	4.54	0.62	1791	4	[Ar] 3d2 4s2	6.83
23	50.942	Vanadium	V	1,890	3,380	6.11	1830	5	[Ar] 3d3 4s2	6.75
24	51.996	Chromium	Cr	1,857	2,672	7.19	0.04	1797	6	[Ar] 3d5 4s1	6.77
25	54.938	Manganese	Mn	1,245	1,962	7.43	0.09	1774	7	[Ar] 3d5 4s2	7.43
26	55.845	Iron	Fe	1,535	2,750	7.87	5.05	ancient	8	[Ar] 3d6 4s2	7.90
27	58.933	Cobalt	Co	1,495	2,870	8.90	1735	9	[Ar] 3d7 4s2	7.88
28	58.693	Nickel	Ni	1,453	2,732	8.90	0.02	1751	10	[Ar] 3d8 4s2	7.64
29	63.546	Copper	Cu	1,083	2,567	8.96	ancient	11	[Ar] 3d10 4s1	7.73
30	65.390	Zinc	Zn	420	907	7.13	ancient	12	[Ar] 3d10 4s2	9.39
31	69.723	Gallium	Ga	30	2,403	5.91	1875	13	[Ar] 3d10 4s2 4p1	6.00
32	72.640	Germanium	Ge	937	2,830	5.32	1886	14	[Ar] 3d10 4s2 4p2	7.90
33	74.922	Arsenic	As	81	613	5.72	ancient	15	[Ar] 3d10 4s2 4p3	9.79
34	78.960	Selenium	Se	217	685	4.79	1817	16	[Ar] 3d10 4s2 4p4	9.75
35	79.904	Bromine	Br	-7	59	3.12	1826	17	[Ar] 3d10 4s2 4p5	11.81
36	83.800	Krypton	Kr	-157	-153	3.75	1898	18	[Ar] 3d10 4s2 4p6	14.00
37	85.468	Rubidium	Rb	39	688	1.63	1861	1	[Kr] 5s1	4.18
38	87.620	Strontium	Sr	769	1,384	2.54	1790	2	[Kr] 5s2	5.69
39	88.906	Yttrium	Y	1,523	3,337	4.47	1794	3	[Kr] 4d1 5s2	6.22
40	91.224	Zirconium	Zr	1,852	4,377	6.51	0.03	1789	4	[Kr] 4d2 5s2	6.63
41	92.906	Niobium	Nb	2,468	4,927	8.57	1801	5	[Kr] 4d4 5s1	6.76
42	95.940	Molybdenum	Mo	2,617	4,612	10.22	1781	6	[Kr] 4d5 5s1	7.09
43	*	98.000	Technetium	Tc	2,200	4,877	11.50	1937	7	[Kr] 4d5 5s2	7.28
44	101.070	Ruthenium	Ru	2,250	3,900	12.37	1844	8	[Kr] 4d7 5s1	7.36
45	102.906	Rhodium	Rh	1,966	3,727	12.41	1803	9	[Kr] 4d8 5s1	7.46
46	106.420	Palladium	Pd	1,552	2,927	12.02	1803	10	[Kr] 4d10	8.34
47	107.868	Silver	Ag	962	2,212	10.50	ancient	11	[Kr] 4d10 5s1	7.58
48	112.411	Cadmium	Cd	321	765	8.65	1817	12	[Kr] 4d10 5s2	8.99
49	114.818	Indium	In	157	2,000	7.31	1863	13	[Kr] 4d10 5s2 5p1	5.79
50	118.710	Tin	Sn	232	2,270	7.31	ancient	14	[Kr] 4d10 5s2 5p2	7.34
51	121.760	Antimony	Sb	630	1,750	6.68	ancient	15	[Kr] 4d10 5s2 5p3	8.61
52	127.600	Tellurium	Te	449	990	6.24	1783	16	[Kr] 4d10 5s2 5p4	9.01
53	126.905	Iodine	I	114	184	4.93	1811	17	[Kr] 4d10 5s2 5p5	10.45
54	131.293	Xenon	Xe	-112	-108	5.90	1898	18	[Kr] 4d10 5s2 5p6	12.13
55	132.906	Cesium	Cs	29	678	1.87	1860	1	[Xe] 6s1	3.89
56	137.327	Barium	Ba	725	1,140	3.59	0.05	1808	2	[Xe] 6s2	5.21
57	138.906	Lanthanum	La	920	3,469	6.15	1839	3	[Xe] 5d1 6s2	5.58
58	140.116	Cerium	Ce	795	3,257	6.77	1803	101	[Xe] 4f1 5d1 6s2	5.54
59	140.908	Praseodymium	Pr	935	3,127	6.77	1885	101	[Xe] 4f3 6s2	5.47
60	144.240	Neodymium	Nd	1,010	3,127	7.01	1885	101	[Xe] 4f4 6s2	5.53
61	*	145.000	Promethium	Pm	1,100	3,000	7.30	1945	101	[Xe] 4f5 6s2	5.58
62	150.360	Samarium	Sm	1,072	1,900	7.52	1879	101	[Xe] 4f6 6s2	5.64
63	151.964	Europium	Eu	822	1,597	5.24	1901	101	[Xe] 4f7 6s2	5.67
64	157.250	Gadolinium	Gd	1,311	3,233	7.90	1880	101	[Xe] 4f7 5d1 6s2	6.15
65	158.925	Terbium	Tb	1,360	3,041	8.23	1843	101	[Xe] 4f9 6s2	5.86
66	162.500	Dysprosium	Dy	1,412	2,562	8.55	1886	101	[Xe] 4f10 6s2	5.94
67	164.930	Holmium	Ho	1,470	2,720	8.80	1867	101	[Xe] 4f11 6s2	6.02
68	167.259	Erbium	Er	1,522	2,510	9.07	1842	101	[Xe] 4f12 6s2	6.11
69	168.934	Thulium	Tm	1,545	1,727	9.32	1879	101	[Xe] 4f13 6s2	6.18
70	173.040	Ytterbium	Yb	824	1,466	6.90	1878	101	[Xe] 4f14 6s2	6.25
71	174.967	Lutetium	Lu	1,656	3,315	9.84	1907	101	[Xe] 4f14 5d1 6s2	5.43
72	178.490	Hafnium	Hf	2,150	5,400	13.31	1923	4	[Xe] 4f14 5d2 6s2	6.83
73	180.948	Tantalum	Ta	2,996	5,425	16.65	1802	5	[Xe] 4f14 5d3 6s2	7.55
74	183.840	Tungsten	W	3,410	5,660	19.35	1783	6	[Xe] 4f14 5d4 6s2	7.86
75	186.207	Rhenium	Re	3,180	5,627	21.04	1925	7	[Xe] 4f14 5d5 6s2	7.83
76	190.230	Osmium	Os	3,045	5,027	22.60	1803	8	[Xe] 4f14 5d6 6s2	8.44
77	192.217	Iridium	Ir	2,410	4,527	22.40	1803	9	[Xe] 4f14 5d7 6s2	8.97
78	195.078	Platinum	Pt	1,772	3,827	21.45	1735	10	[Xe] 4f14 5d9 6s1	8.96
79	196.967	Gold	Au	1,064	2,807	19.32	ancient	11	[Xe] 4f14 5d10 6s1	9.23
80	200.590	Mercury	Hg	-39	357	13.55	ancient	12	[Xe] 4f14 5d10 6s2	10.44
81	204.383	Thallium	Tl	303	1,457	11.85	1861	13	[Xe] 4f14 5d10 6s2 6p1	6.11
82	207.200	Lead	Pb	327	1,740	11.35	ancient	14	[Xe] 4f14 5d10 6s2 6p2	7.42
83	208.980	Bismuth	Bi	271	1,560	9.75	ancient	15	[Xe] 4f14 5d10 6s2 6p3	7.29
84	*	209.000	Polonium	Po	254	962	9.30	1898	16	[Xe] 4f14 5d10 6s2 6p4	8.42
85	*	210.000	Astatine	At	302	337	0.00	1940	17	[Xe] 4f14 5d10 6s2 6p5	9.30
86	*	222.000	Radon	Rn	-71	-62	9.73	1900	18	[Xe] 4f14 5d10 6s2 6p6	10.75
87	*	223.000	Francium	Fr	27	677	0.00	1939	1	[Rn] 7s1	4.07
88	*	226.000	Radium	Ra	700	1,737	5.50	1898	2	[Rn] 7s2	5.28
89	*	227.000	Actinium	Ac	1,050	3,200	10.07	1899	3	[Rn] 6d1 7s2	5.17
90	232.038	Thorium	Th	1,750	4,790	11.72	1829	102	[Rn] 6d2 7s2	6.31
91	231.036	Protactinium	Pa	1,568	0	15.40	1913	102	[Rn] 5f2 6d1 7s2	5.89
92	238.029	Uranium	U	1,132	3,818	18.95	1789	102	[Rn] 5f3 6d1 7s2	6.19
93	*	237.000	Neptunium	Np	640	3,902	20.20	1940	102	[Rn] 5f4 6d1 7s2	6.27
94	*	244.000	Plutonium	Pu	640	3,235	19.84	1940	102	[Rn] 5f6 7s2	6.03
95	*	243.000	Americium	Am	994	2,607	13.67	1944	102	[Rn] 5f7 7s2	5.97
96	*	247.000	Curium	Cm	1,340	0	13.50	1944	102	5.99
97	*	247.000	Berkelium	Bk	986	0	14.78	1949	102	6.20
98	*	251.000	Californium	Cf	900	0	15.10	1950	102	6.28
99	*	252.000	Einsteinium	Es	860	0	0.00	1952	102	6.42
100	*	257.000	Fermium	Fm	1,527	0	0.00	1952	102	6.50
101	*	258.000	Mendelevium	Md	0	0	0.00	1955	102	6.58
102	*	259.000	Nobelium	No	827	0	0.00	1958	102	6.65
103	*	262.000	Lawrencium	Lr	1,627	0	0.00	1961	102	4.90
104	*	261.000	Rutherfordium	Rf	0	0	0.00	1964	4	0.00
105	*	262.000	Dubnium	Db	0	0	0.00	1967	5	0.00
106	*	266.000	Seaborgium	Sg	0	0	0.00	1974	6	0.00
107	*	264.000	Bohrium	Bh	0	0	0.00	1981	7	0.00
108	*	277.000	Hassium	Hs	0	0	0.00	1984	8	0.00
109	*	268.000	Meitnerium	Mt	0	0	0.00	1982	9	0.00
No.		Atomic weight	Name	Sym.	M.P. (°C)	B.P. (°C)	Density* (g/cm3)	Earth crust (%)*	Discovery (Year)	Group*	Electron configuration	Ionization energy (eV)

Notes:
• Density of elements with boiling points below 0°C is given in g/l. In a sorted list, these elements are shown before other elements that have boiling points >0°C.
• Earth crust composition average values are from a report by F. W. Clarke and H. S. Washington, 1924. Elemental composition of crustal rocks differ between different localities (see article).
• Group: There are only 18 groups in the periodic table that constitute the columns of the table. Lanthanoids and Actinoids are numbered as 101 and 102 to separate them in sorting by group.
• The elements marked with an asterisk (in the 2nd column) have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Abbreviations and Definitions:

The number of protons of a neutral atom and its ion is the same. 40 Ca and 40 Ca 2+ both have 20 protons. 40 Ca has 20 electrons. 40 Ca 2+ has 18 electrons. The +2 charge on 40 Ca 2+ indicates that 40 Ca 2+ has 2 less electrons than 40 Ca. 35 Cl-and 40 Ca 2+ have the same number of electrons.

No. - Atomic Number; M.P. - melting point; B.P. - boiling point

Atomic number: The number of protons in an atom. Each element is uniquely defined by its atomic number.

Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, ¹²C, that is taken as a standard element with an atomic mass of 12. This isotope of carbon has 6 protons and 6 neutrons. Thus, each proton and neutron has a mass of about 1 amu.

Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus. Elements have more than one isotope with varying numbers of neutrons. For example, there are two common isotopes of carbon, ¹²C and ¹³C which have 6 and 7 neutrons respectively. The abundances of different isotopes of elements vary in nature depending on the source of materials. For relative abundances of isotopes in nature see reference on Atomic Weights and Isotopic Compositions.

Ca Atomic Number Of Protons And Electrons

Atomic weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure Appl. Chem. 73:667-683, 2001). The elements marked with an asterisk have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.

Electron configuration: See next page for explanation of electron configuration of atoms.

Ionization energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground level. The table lists only the first IE in eV units. To convert to kJ/mol multiply by 96.4869. Reference: NIST Reference Table on Ground states and ionization energies for the neutral atoms. IE decreases going down a column of the periodic table, and increases from left to right in a row. Thus, alkali metals have the lowest IE in a period and Rare gases have the highest.

Other resources related to the Periodic Table

• Chemical Evolution of the Universe
  

We remember from our school chemistry course that every element has its own specific atomic number. It is the same as the number of protons that the atom of each element has, so sometimes atomic number is called proton number. It is always the whole number and it ranges from 1 to 118, according to the number of the element in the Periodic Table. This number can be really important and something essential to know, in relation to a certain chemical element which is the issue of our interest at the moment.

Why is this so? Why is the atomic number so important? First of all, it is the number that makes elements different from one another as it shows the number of protons in their nuclei. Also, knowing the atomic number of an element can give us an idea about the position of the element in the Periodic Table. Atomic number of an element never changes: for example, the atomic number of oxygen is always 8, and the atomic number of Chlorine is always 18. The atomic number is marked with the symbol Z, taken from a German word zahl (or atomzahl, which is 'atomic number' in German).

This website is created for those who need to know the atomic number of a central chemical element. By using our website, you can do it in just one click and receive short and correct information on this matter. There is also some extra summary on every each chemical element which can be found at our website, including the atomic weight of each element, as well as physical and chemical properties of every element and its importance. Use this website at any time when you need to get fast and precise information about atomic or proton number of chemical elements.

List of chemical elements in periodic table with atomic number, chemical symbol and atomic weight. You can sort the elements by clicking on the table headers. Please click on the element name for complete list of element properties.

Atomic Number	Chemical Symbol	Element Name	Atomic Weight (u)
1	H	Hydrogen	1.008
2	He	Helium	4.003
3	Li	Lithium	6.94
4	Be	Beryllium	9.012
5	B	Boron	10.81
6	C	Carbon	12.011
7	N	Nitrogen	14.007
8	O	Oxygen	15.999
9	F	Fluorine	18.998
10	Ne	Neon	20.18
11	Na	Sodium	22.99
12	Mg	Magnesium	24.305
13	Al	Aluminium	26.982
14	Si	Silicon	28.085
15	P	Phosphorus	30.974
16	S	Sulfur	32.06
17	Cl	Chlorine	35.45
18	Ar	Argon	39.948
19	K	Potassium	39.098
20	Ca	Calcium	40.078
21	Sc	Scandium	44.956
22	Ti	Titanium	47.867
23	V	Vanadium	50.942
24	Cr	Chromium	51.996
25	Mn	Manganese	54.938
26	Fe	Iron	55.845
27	Co	Cobalt	58.933
28	Ni	Nickel	58.693
29	Cu	Copper	63.546
30	Zn	Zinc	65.38
31	Ga	Gallium	69.723
32	Ge	Germanium	72.63
33	As	Arsenic	74.922
34	Se	Selenium	78.971
35	Br	Bromine	79.904
36	Kr	Krypton	83.798
37	Rb	Rubidium	85.468
38	Sr	Strontium	87.62
39	Y	Yttrium	88.906
40	Zr	Zirconium	91.224
41	Nb	Niobium	92.906
42	Mo	Molybdenum	95.95
43	Tc	Technetium	98
44	Ru	Ruthenium	101.07
45	Rh	Rhodium	102.906
46	Pd	Palladium	106.42
47	Ag	Silver	107.868
48	Cd	Cadmium	112.414
49	In	Indium	114.818
50	Sn	Tin	118.71
51	Sb	Antimony	121.76
52	Te	Tellurium	127.6
53	I	Iodine	126.904
54	Xe	Xenon	131.293
55	Cs	Caesium	132.905
56	Ba	Barium	137.327
57	La	Lanthanum	138.905
58	Ce	Cerium	140.116
59	Pr	Praseodymium	140.908
60	Nd	Neodymium	144.242
61	Pm	Promethium	145
62	Sm	Samarium	150.36
63	Eu	Europium	151.964
64	Gd	Gadolinium	157.25
65	Tb	Terbium	158.925
66	Dy	Dysprosium	162.5
67	Ho	Holmium	164.93
68	Er	Erbium	167.259
69	Tm	Thulium	168.934
70	Yb	Ytterbium	173.045
71	Lu	Lutetium	174.967
72	Hf	Hafnium	178.49
73	Ta	Tantalum	180.948
74	W	Tungsten	183.84
75	Re	Rhenium	186.207
76	Os	Osmium	190.23
77	Ir	Iridium	192.217
78	Pt	Platinum	195.084
79	Au	Gold	196.967
80	Hg	Mercury	200.592
81	Tl	Thallium	204.38
82	Pb	Lead	207.2
83	Bi	Bismuth	208.98
84	Po	Polonium	209
85	At	Astatine	210
86	Rn	Radon	222
87	Fr	Francium	223
88	Ra	Radium	226
89	Ac	Actinium	227
90	Th	Thorium	232.038
91	Pa	Protactinium	231.036
92	U	Uranium	238.029
93	Np	Neptunium	237
94	Pu	Plutonium	244
95	Am	Americium	243
96	Cm	Curium	247
97	Bk	Berkelium	247
98	Cf	Californium	251
99	Es	Einsteinium	252
100	Fm	Fermium	257
101	Md	Mendelevium	258
102	No	Nobelium	259
103	Lr	Lawrencium	266
104	Rf	Rutherfordium	267
105	Db	Dubnium	268
106	Sg	Seaborgium	269
107	Bh	Bohrium	270
108	Hs	Hassium	277
109	Mt	Meitnerium	278
110	Ds	Darmstadtium	281
111	Rg	Roentgenium	282
112	Cn	Copernicium	285
113	Nh	Nihonium	286
114	Fl	Flerovium	289
115	Mc	Moscovium	290
116	Lv	Livermorium	293
117	Ts	Tennessine	294
118	Og	Oganesson	294

Lists of Elements in Periodic Table

You can also list the elements in various ordered properties with printable tables below.

Ca Atomic Number

Lists of Elements by Group Number in Periodic Table

Calcium Atom

Ca Ka Atomic Number

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