How to Find the Charge of a Compound

Atoms of the elements display a range of charges, but you can predict the most common charge of most elements using its element group.

Here is a chart of element charges and an explanation of how to find the charge of an element if you don't know it. The difference between charge, oxidation state, and valence is explained, too. You can download and print these graphics and tables for references.

How to Find the Charge of an Element

There are four ways to find the charge of an element:

1. Use the periodic table. The usual charge of an element is common to its group.
   Group 1 (Alkali Metals): 1+
   Group 2 (Alkaline Earth Metals): 2+
   Groups 3-12 (Transition Metals): Variable positive charges
   Lanthanide and Actinide Series: Variable positive charges
   Group 13: 3+
   Group 14: 4+ or 4-
   Group 15: 3-
   Group 16: 2-
   Group 17 (Halogens): 1-
   Group 18 (Noble Gases): 0
   
2. Use a chart. Charts come from empirical data on the real behavior of elements, which may differ somewhere from the periodic table predictions. Here are two charts. The first shows common element charges, while the second shows all the element charges for the first 45 elements (most common charges in bold).
3. For a single atom, the charge is the number of protons minus the number of electrons.
4. Find the charge by balancing charge in a compound.

Number	Element	Charge
1	hydrogen	1+
2	helium	0
3	lithium	1+
4	beryllium	2+
5	boron	3-, 3+
6	carbon	4+
7	nitrogen	3-
8	oxygen	2-
9	fluorine	1-
10	neon	0
11	sodium	1+
12	magnesium	2+
13	aluminum	3+
14	silicon	4+, 4-
15	phosphorus	5+, 3+, 3-
16	sulfur	2-, 2+, 4+, 6+
17	chlorine	1-
18	argon	0
19	potassium	1+
20	calcium	2+
21	scandium	3+
22	titanium	4+, 3+
23	vanadium	2+, 3+, 4+, 5+
24	chromium	2+, 3+, 6+
25	manganese	2+, 4+, 7+
26	iron	2+, 3+
27	cobalt	2+, 3+
28	nickel	2+
29	copper	1+, 2+
30	zinc	2+
31	gallium	3+
32	germanium	4-, 2+, 4+
33	arsenic	3-, 3+, 5+
34	selenium	2-, 4+, 6+
35	bromine	1-, 1+, 5+
36	krypton	0
37	rubidium	1+
38	strontium	2+
39	yttrium	3+
40	zirconium	4+
41	niobium	3+, 5+
42	molybdenum	3+, 6+
43	technetium	6+
44	ruthenium	3+, 4+, 8+
45	rhodium	4+
46	palladium	2+, 4+
47	silver	1+
48	cadmium	2+
49	indium	3+
50	tin	2+, 4+
51	antimony	3-, 3+, 5+
52	tellurium	2-, 4+, 6+
53	iodine	1-
54	xenon	0
55	cesium	1+
56	barium	2+
57	lanthanum	3+
58	cerium	3+, 4+
59	praseodymium	3+
60	neodymium	3+, 4+
61	promethium	3+
62	samarium	3+
63	europium	3+
64	gadolinium	3+
65	terbium	3+, 4+
66	dysprosium	3+
67	holmium	3+
68	erbium	3+
69	thulium	3+
70	ytterbium	3+
71	lutetium	3+
72	hafnium	4+
73	tantalum	5+
74	tungsten	6+
75	rhenium	2+, 4+, 6+, 7+
76	osmium	3+, 4+, 6+, 8+
77	iridium	3+, 4+, 6+
78	platinum	2+, 4+, 6+
79	gold	1+, 2+, 3+
80	mercury	1+, 2+
81	thallium	1+, 3+
82	lead	2+, 4+
83	bismuth	3+
84	polonium	2+, 4+
85	astatine	?
86	radon	0
87	francium	?
88	radium	2+
89	actinium	3+
90	thorium	4+
91	protactinium	5+
92	uranium	3+, 4+, 6+

Table of common element charges

All element valence charges for hydrogen through rhodium.

Charge, Valence, and Oxidation State

In many texts, the terms charge (or formal charge), valence, and oxidation number are used interchangeably. These three terms are related, but have slightly different definitions:

• Charge (Formal Charge): Charge is the electrical charge of an atom when all of its ligands are removed homolytically. In homolytic cleavage, electrons sharing a bond are split equally between the two atoms.
• Oxidation State (Oxidation Number): Oxidation state is the charge on an atom when all of its ligands are removed heterolytically. In this case, the more electronegative atom gets the electrons.
• Valence: Valence is the number of electrons used by an atom to form a chemical bond.

Confused? Usually, what you want to know is the oxidation state, which carries both a number and a positive or negative sign. For example, in HCl, both H and Cl have a valence of 1. One electron from each atom participates in chemical bond formation. But, hydrogen has an oxidation state of +1, while chloride has an oxidation state of -1. From the oxidation state, you know the charge (or vice versa). We write the charges of the atoms as H⁺ and Cl^–.

References

• Karen, P.; McArdle, P.; Takats, J. (2016). "Comprehensive definition of oxidation state (IUPAC Recommendations 2016)".Pure Appl. Chem.88 (8): 831–839. doi:10.1515/pac-2015-1204
• Parkin, Gerard (May 2006). "Valence, Oxidation Number, and Formal Charge: Three Related but Fundamentally Different Concepts".Journal of Chemical Education.83 (5): 791. doi:10.1021/ed083p791

How to Find the Charge of a Compound

Source: https://sciencenotes.org/element-charges-chart-how-to-know-the-charge-of-an-atom/

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