Atomic Mass and Avogadro Number

by Dasa . 27 No 2021

The ‘mol’ is the SI (International System of Units) base unit for the amount of substance. A ‘mol’ contains 6.02214076×10²³ elementary entities, which may be atoms, molecules, ions, or electrons. The number 6.02214076×10²³ is called Avogadro’s Number.

1 mol = 6.02214076×10²³ elements.

The below table shows the details of protons, neutrons, electrons, mass number, and atomic mass for various elements in the Periodic Table.

Protons and neutrons have mass. But electrons do not have mass. So when you add up the number of protons & neutrons, we get the Mass Number. The last column of the table shows the atomic mass in gram/mol.

Isotopes:

Atomic mass & mass numbers should be the same. But, Some elements will have different quantities of the neutron in nature. So Atomic mass indicates the average of masses. These elements that differ in their number of neutrons are called Isotops.

For example,
Most Carbon in the earth will have six neutrons, but 1.1% of the carbon present has seven neutrons.

As per the table,

1 mol of H = 1 proton
= 1.0080 grams
That means,

1 mol of any element contains 6.02214076×10²³ elements.
6.02214076×10²³ elements of H = 1.0080 grams

1 element of H = $\dfrac{1.0080}{6.02214076 * 10^{23}}$ grams/element

= $1.6738 * 10^{-24}$ grams/element

Atomic Number	Symbol	Name	Protons	Neutrons	Electrons	Mass Number	Atomic Mass (g/mol)
1	H	Hydrogen	1	0	1	1	1.0080
2	He	Helium	2	2	2	4	4.0026
3	Li	Lithium	3	4	3	7	7.0000
4	Be	Beryllium	4	5	4	9	9.0122
5	B	Boron	5	6	5	11	10.8100
6	C	Carbon	6	6	6	12	12.0110
7	N	Nitrogen	7	7	7	14	14.0070
8	O	Oxygen	8	8	8	16	15.9990
9	F	Fluorine	9	10	9	19	18.9984
10	Ne	Neon	10	10	10	20	20.1800
11	Na	Sodium	11	12	11	23	22.9898
12	Mg	Magnesium	12	12	12	24	24.3050
13	Al	Aluminum	13	14	13	27	26.9815
14	Si	Silicon	14	14	14	28	28.0850
15	P	Phosphorus	15	16	15	31	30.9738
16	S	Sulfur	16	16	16	32	32.0700
17	Cl	Chlorine	17	18	17	35	35.4500
18	Ar	Argon	18	22	18	40	39.9000
19	K	Potassium	19	20	19	39	39.0983
20	Ca	Calcium	20	20	20	40	40.0800
21	Sc	Scandium	21	24	21	45	44.9559
22	Ti	Titanium	22	26	22	48	47.8670
23	V	Vanadium	23	28	23	51	50.9415
24	Cr	Chromium	24	28	24	52	51.9960
25	Mn	Manganese	25	30	25	55	54.9380
26	Fe	Iron	26	30	26	56	55.8400
27	Co	Cobalt	27	32	27	59	58.9332
28	Ni	Nickel	28	30	28	58	58.6930
29	Cu	Copper	29	36	29	65	63.5500
30	Zn	Zinc	30	35	30	65	65.4000
31	Ga	Gallium	31	38	31	69	69.7230
32	Ge	Germanium	32	41	32	73	72.6300
33	As	Arsenic	33	42	33	75	74.9216
34	Se	Selenium	34	45	34	79	78.9700
35	Br	Bromine	35	46	35	81	79.9000
36	Kr	Krypton	36	50	36	86	83.8000
37	Rb	Rubidium	37	48	37	85	85.4680
38	Sr	Strontium	38	50	38	88	87.6200
39	Y	Yttrium	39	50	39	89	88.9058
40	Zr	Zirconium	40	52	40	92	91.2200
41	Nb	Niobium	41	52	41	93	92.9064
42	Mo	Molybdenum	42	54	42	96	95.9500
43	Tc	Technetium	43	54	43	97	96.9064
44	Ru	Ruthenium	44	57	44	101	101.1000
45	Rh	Rhodium	45	58	45	103	102.9055
46	Pd	Palladium	46	60	46	106	106.4200
47	Ag	Silver	47	61	47	108	107.8680
48	Cd	Cadmium	48	64	48	112	112.4100
49	In	Indium	49	66	49	115	114.8180
50	Sn	Tin	50	69	50	119	118.7100
51	Sb	Antimony	51	71	51	122	121.7600
52	Te	Tellurium	52	76	52	128	127.6000
53	I	Iodine	53	74	53	127	126.9045
54	Xe	Xenon	54	77	54	131	131.2900
55	Cs	Cesium	55	78	55	133	132.9055
56	Ba	Barium	56	81	56	137	137.3300
57	La	Lanthanum	57	82	57	139	138.9055
58	Ce	Cerium	58	82	58	140	140.1160
59	Pr	Praseodymium	59	82	59	141	140.9077
60	Nd	Neodymium	60	84	60	144	144.2400
61	Pm	Promethium	61	84	61	145	144.9128
62	Sm	Samarium	62	88	62	150	150.4000
63	Eu	Europium	63	89	63	152	151.9640
64	Gd	Gadolinium	64	93	64	157	157.2000
65	Tb	Terbium	65	94	65	159	158.9254
66	Dy	Dysprosium	66	97	66	163	162.5000
67	Ho	Holmium	67	98	67	165	164.9303
68	Er	Erbium	68	99	68	167	167.2600
69	Tm	Thulium	69	100	69	169	168.9342
70	Yb	Ytterbium	70	103	70	173	173.0500
71	Lu	Lutetium	71	104	71	175	174.9668
72	Hf	Hafnium	72	106	72	178	178.4900
73	Ta	Tantalum	73	108	73	181	180.9479
74	W	Tungsten	74	110	74	184	183.8400
75	Re	Rhenium	75	111	75	186	186.2070
76	Os	Osmium	76	114	76	190	190.2000
77	Ir	Iridium	77	115	77	192	192.2200
78	Pt	Platinum	78	117	78	195	195.0800
79	Au	Gold	79	118	79	197	196.9666
80	Hg	Mercury	80	121	80	201	200.5900
81	Tl	Thallium	81	123	81	204	204.3830
82	Pb	Lead	82	125	82	207	207.0000
83	Bi	Bismuth	83	126	83	209	208.9804
84	Po	Polonium	84	125	84	209	208.9824
85	At	Astatine	85	125	85	210	209.9872
86	Rn	Radon	86	136	86	222	222.0176
87	Fr	Francium	87	136	87	223	223.0197
88	Ra	Radium	88	138	88	226	226.0254
89	Ac	Actinium	89	138	89	227	227.0278
90	Th	Thorium	90	142	90	232	232.0380
91	Pa	Protactinium	91	140	91	231	231.0359
92	U	Uranium	92	146	92	238	238.0289
93	Np	Neptunium	93	144	93	237	237.0482
94	Pu	Plutonium	94	150	94	244	244.0642
95	Am	Americium	95	148	95	243	243.0614
96	Cm	Curium	96	151	96	247	247.0704
97	Bk	Berkelium	97	150	97	247	247.0703
98	Cf	Californium	98	153	98	251	251.0796
99	Es	Einsteinium	99	153	99	252	252.0830
100	Fm	Fermium	100	157	100	257	257.0951
101	Md	Mendelevium	101	157	101	258	258.0984
102	No	Nobelium	102	157	102	259	259.1010
103	Lr	Lawrencium	103	163	103	266	266.1200
104	Rf	Rutherfordium	104	163	104	267	267.1220
105	Db	Dubnium	105	163	105	268	268.1260
106	Sg	Seaborgium	106	163	106	269	269.1280
107	Bh	Bohrium	107	163	107	270	270.1330
108	Hs	Hassium	108	161	108	269	269.1336
109	Mt	Meitnerium	109	168	109	277	277.1540
110	Ds	Darmstadtium	110	172	110	282	282.1660
111	Rg	Roentgenium	111	171	111	282	282.1690
112	Cn	Copernicium	112	174	112	286	286.1790
113	Nh	Nihonium	113	173	113	286	286.1820
114	Fl	Flerovium	114	176	114	290	290.1920
115	Mc	Moscovium	115	175	115	290	290.1960
116	Lv	Livermorium	116	177	116	293	293.2050
117	Ts	Tennessine	117	177	117	294	294.2110
118	Og	Oganesson	118	176	118	295	295.2160