Atomic Number 20

Atomic Number 207
Atomic Number 20 To 30
Element With 20 Atomic Number
Atomic Number 20 Mass Number 42

Atomic Number 207

A neutral atom with atomic number 20 will have 20 electrons. The atomic number is, by definiton, the number of protons in an atom's nucleus but for a neutral atom it's also equal to the number of electrons. Each element has a different, unique number of protons that determines its identity.
The atomic number of an atom defines what element the atom is. It is the number of protons on the nucleus of the atom. The atomic number of Ca is 20, therefore it has 20 protons. Any atom that has 20 protons will always be a Ca atom. So the answer is. 20 protons, 25 neurons, 20 electrons.

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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)

Atomic Number Name Symbol Standard atomic weight Group Period. 1 Hydrogen H 1.00794(7)2 3 4 1 1. 2 Helium He 4.002602(2)2 4 18 1. 3 Lithium Li 6.941(2)2 3 4 5 1 2.

Notes: Bridge adobe download mac.
• 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.

Atomic Number 20 To 30

Abbreviations and Definitions:

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.

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): Can you download shows on hulu on mac. 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.

Element With 20 Atomic Number

Other resources related to the Periodic Table

Atomic Number 20 Mass Number 42

Chemical Evolution of the Universe