Valence Electrons of Every Element

Outer-shell electron counts, the group rule that predicts them, and where that rule stops working.

Valence electrons are the outermost electrons — the ones that actually do chemistry. An atom's entire personality comes down to how many it has and how far it is from a full shell. Sodium has one it would rather be rid of; chlorine is one short and will take sodium's. That single fact is table salt.

The group rule

For main-group elements the column number gives the answer directly: groups 1 and 2 have 1 and 2 valence electrons, and groups 13 through 18 have the group number minus ten. Group 16 has 6, group 17 has 7, and group 18 has 8 — a full shell, which is precisely why the noble gases do nothing.

Where it stops working

In the d- and f-blocks the outer s electrons and the inner d or f electrons sit at similar energies, so the number that can participate in bonding varies with the compound. Rather than print a number we would have to qualify, this table marks those elements variable and shows their configuration instead.

Valence electron count for every element
#	Element	Valence electrons	Outer configuration	Group	Shells
1	HHydrogen	1	1s¹	1	1
2	HeHelium	2	1s²	18	2
3	LiLithium	1	2s¹	1	2, 1
4	BeBeryllium	2	2s²	2	2, 2
5	BBoron	3	2s² 2p¹	13	2, 3
6	CCarbon	4	2s² 2p²	14	2, 4
7	NNitrogen	5	2s² 2p³	15	2, 5
8	OOxygen	6	2s² 2p⁴	16	2, 6
9	FFluorine	7	2s² 2p⁵	17	2, 7
10	NeNeon	8	2s² 2p⁶	18	2, 8
11	NaSodium	1	3s¹	1	2, 8, 1
12	MgMagnesium	2	3s²	2	2, 8, 2
13	AlAluminum	3	3s² 3p¹	13	2, 8, 3
14	SiSilicon	4	3s² 3p²	14	2, 8, 4
15	PPhosphorus	5	3s² 3p³	15	2, 8, 5
16	SSulfur	6	3s² 3p⁴	16	2, 8, 6
17	ClChlorine	7	3s² 3p⁵	17	2, 8, 7
18	ArArgon	8	3s² 3p⁶	18	2, 8, 8
19	KPotassium	1	4s¹	1	2, 8, 8, 1
20	CaCalcium	2	4s²	2	2, 8, 8, 2
21	ScScandium	variable	4s² 3d¹	3	2, 8, 9, 2
22	TiTitanium	variable	4s² 3d²	4	2, 8, 10, 2
23	VVanadium	variable	4s² 3d³	5	2, 8, 11, 2
24	CrChromium	variable	3d⁵ 4s¹	6	2, 8, 13, 1
25	MnManganese	variable	4s² 3d⁵	7	2, 8, 13, 2
26	FeIron	variable	4s² 3d⁶	8	2, 8, 14, 2
27	CoCobalt	variable	4s² 3d⁷	9	2, 8, 15, 2
28	NiNickel	variable	4s² 3d⁸	10	2, 8, 16, 2
29	CuCopper	variable	4s¹ 3d¹⁰	11	2, 8, 18, 1
30	ZnZinc	variable	4s² 3d¹⁰	12	2, 8, 18, 2
31	GaGallium	3	4s² 3d¹⁰ 4p¹	13	2, 8, 18, 3
32	GeGermanium	4	4s² 3d¹⁰ 4p²	14	2, 8, 18, 4
33	AsArsenic	5	4s² 3d¹⁰ 4p³	15	2, 8, 18, 5
34	SeSelenium	6	4s² 3d¹⁰ 4p⁴	16	2, 8, 18, 6
35	BrBromine	7	4s² 3d¹⁰ 4p⁵	17	2, 8, 18, 7
36	KrKrypton	8	4s² 3d¹⁰ 4p⁶	18	2, 8, 18, 8
37	RbRubidium	1	5s¹	1	2, 8, 18, 8, 1
38	SrStrontium	2	5s²	2	2, 8, 18, 8, 2
39	YYttrium	variable	5s² 4d¹	3	2, 8, 18, 9, 2
40	ZrZirconium	variable	5s² 4d²	4	2, 8, 18, 10, 2
41	NbNiobium	variable	5s¹ 4d⁴	5	2, 8, 18, 12, 1
42	MoMolybdenum	variable	5s¹ 4d⁵	6	2, 8, 18, 13, 1
43	TcTechnetium	variable	5s² 4d⁵	7	2, 8, 18, 13, 2
44	RuRuthenium	variable	5s¹ 4d⁷	8	2, 8, 18, 15, 1
45	RhRhodium	variable	5s¹ 4d⁸	9	2, 8, 18, 16, 1
46	PdPalladium	variable	4d¹⁰	10	2, 8, 18, 18
47	AgSilver	variable	5s¹ 4d¹⁰	11	2, 8, 18, 18, 1
48	CdCadmium	variable	5s² 4d¹⁰	12	2, 8, 18, 18, 2
49	InIndium	3	5s² 4d¹⁰ 5p¹	13	2, 8, 18, 18, 3
50	SnTin	4	5s² 4d¹⁰ 5p²	14	2, 8, 18, 18, 4
51	SbAntimony	5	5s² 4d¹⁰ 5p³	15	2, 8, 18, 18, 5
52	TeTellurium	6	5s² 4d¹⁰ 5p⁴	16	2, 8, 18, 18, 6
53	IIodine	7	5s² 4d¹⁰ 5p⁵	17	2, 8, 18, 18, 7
54	XeXenon	8	5s² 4d¹⁰ 5p⁶	18	2, 8, 18, 18, 8
55	CsCesium	1	6s¹	1	2, 8, 18, 18, 8, 1
56	BaBarium	2	6s²	2	2, 8, 18, 18, 8, 2
57	LaLanthanum	variable	6s² 5d¹	f	2, 8, 18, 18, 9, 2
58	CeCerium	variable	6s² 4f¹ 5d¹	f	2, 8, 18, 19, 9, 2
59	PrPraseodymium	variable	6s² 4f³	f	2, 8, 18, 21, 8, 2
60	NdNeodymium	variable	6s² 4f⁴	f	2, 8, 18, 22, 8, 2
61	PmPromethium	variable	6s² 4f⁵	f	2, 8, 18, 23, 8, 2
62	SmSamarium	variable	6s² 4f⁶	f	2, 8, 18, 24, 8, 2
63	EuEuropium	variable	6s² 4f⁷	f	2, 8, 18, 25, 8, 2
64	GdGadolinium	variable	6s² 4f⁷ 5d¹	f	2, 8, 18, 25, 9, 2
65	TbTerbium	variable	6s² 4f⁹	f	2, 8, 18, 27, 8, 2
66	DyDysprosium	variable	6s² 4f¹⁰	f	2, 8, 18, 28, 8, 2
67	HoHolmium	variable	6s² 4f¹¹	f	2, 8, 18, 29, 8, 2
68	ErErbium	variable	6s² 4f¹²	f	2, 8, 18, 30, 8, 2
69	TmThulium	variable	6s² 4f¹³	f	2, 8, 18, 31, 8, 2
70	YbYtterbium	variable	6s² 4f¹⁴	f	2, 8, 18, 32, 8, 2
71	LuLutetium	variable	6s² 4f¹⁴ 5d¹	f	2, 8, 18, 32, 9, 2
72	HfHafnium	variable	6s² 4f¹⁴ 5d²	4	2, 8, 18, 32, 10, 2
73	TaTantalum	variable	6s² 4f¹⁴ 5d³	5	2, 8, 18, 32, 11, 2
74	WTungsten	variable	6s² 4f¹⁴ 5d⁴	6	2, 8, 18, 32, 12, 2
75	ReRhenium	variable	6s² 4f¹⁴ 5d⁵	7	2, 8, 18, 32, 13, 2
76	OsOsmium	variable	6s² 4f¹⁴ 5d⁶	8	2, 8, 18, 32, 14, 2
77	IrIridium	variable	6s² 4f¹⁴ 5d⁷	9	2, 8, 18, 32, 15, 2
78	PtPlatinum	variable	6s¹ 4f¹⁴ 5d⁹	10	2, 8, 18, 32, 17, 1
79	AuGold	variable	6s¹ 4f¹⁴ 5d¹⁰	11	2, 8, 18, 32, 18, 1
80	HgMercury	variable	6s² 4f¹⁴ 5d¹⁰	12	2, 8, 18, 32, 18, 2
81	TlThallium	3	6s² 4f¹⁴ 5d¹⁰ 6p¹	13	2, 8, 18, 32, 18, 3
82	PbLead	4	6s² 4f¹⁴ 5d¹⁰ 6p²	14	2, 8, 18, 32, 18, 4
83	BiBismuth	5	6s² 4f¹⁴ 5d¹⁰ 6p³	15	2, 8, 18, 32, 18, 5
84	PoPolonium	6	6s² 4f¹⁴ 5d¹⁰ 6p⁴	16	2, 8, 18, 32, 18, 6
85	AtAstatine	7	6s² 4f¹⁴ 5d¹⁰ 6p⁵	17	2, 8, 18, 32, 18, 7
86	RnRadon	8	6s² 4f¹⁴ 5d¹⁰ 6p⁶	18	2, 8, 18, 32, 18, 8
87	FrFrancium	1	7s¹	1	2, 8, 18, 32, 18, 8, 1
88	RaRadium	2	7s²	2	2, 8, 18, 32, 18, 8, 2
89	AcActinium	variable	7s² 6d¹	f	2, 8, 18, 32, 18, 9, 2
90	ThThorium	variable	7s² 6d²	f	2, 8, 18, 32, 18, 10, 2
91	PaProtactinium	variable	7s² 5f² 6d¹	f	2, 8, 18, 32, 20, 9, 2
92	UUranium	variable	7s² 5f³ 6d¹	f	2, 8, 18, 32, 21, 9, 2
93	NpNeptunium	variable	7s² 5f⁴ 6d¹	f	2, 8, 18, 32, 22, 9, 2
94	PuPlutonium	variable	7s² 5f⁶	f	2, 8, 18, 32, 24, 8, 2
95	AmAmericium	variable	7s² 5f⁷	f	2, 8, 18, 32, 25, 8, 2
96	CmCurium	variable	7s² 5f⁷ 6d¹	f	2, 8, 18, 32, 25, 9, 2
97	BkBerkelium	variable	7s² 5f⁹	f	2, 8, 18, 32, 27, 8, 2
98	CfCalifornium	variable	7s² 5f¹⁰	f	2, 8, 18, 32, 28, 8, 2
99	EsEinsteinium	variable	7s² 5f¹¹	f	2, 8, 18, 32, 29, 8, 2
100	FmFermium	variable	5f¹² 7s²	f	2, 8, 18, 32, 30, 8, 2
101	MdMendelevium	variable	7s² 5f¹³	f	2, 8, 18, 32, 31, 8, 2
102	NoNobelium	variable	7s² 5f¹⁴	f	2, 8, 18, 32, 32, 8, 2
103	LrLawrencium	variable	7s² 5f¹⁴ 6d¹	f	2, 8, 18, 32, 32, 9, 2
104	RfRutherfordium	variable	7s² 5f¹⁴ 6d²	4	2, 8, 18, 32, 32, 10, 2
105	DbDubnium	variable	7s² 5f¹⁴ 6d³	5	2, 8, 18, 32, 32, 11, 2
106	SgSeaborgium	variable	7s² 5f¹⁴ 6d⁴	6	2, 8, 18, 32, 32, 12, 2
107	BhBohrium	variable	7s² 5f¹⁴ 6d⁵	7	2, 8, 18, 32, 32, 13, 2
108	HsHassium	variable	7s² 5f¹⁴ 6d⁶	8	2, 8, 18, 32, 32, 14, 2
109	MtMeitnerium	variable	7s² 5f¹⁴ 6d⁷ (calculated)	9	2, 8, 18, 32, 32, 15, 2
110	DsDarmstadtium	variable	7s² 5f¹⁴ 6d⁸	10	2, 8, 18, 32, 32, 16, 2
111	RgRoentgenium	variable	7s² 5f¹⁴ 6d⁹	11	2, 8, 18, 32, 32, 17, 2
112	CnCopernicium	variable	7s² 5f¹⁴ 6d¹⁰	12	2, 8, 18, 32, 32, 18, 2
113	NhNihonium	3	5f¹⁴ 6d¹⁰ 7s² 7p¹	13	2, 8, 18, 32, 32, 18, 3
114	FlFlerovium	4	7s² 7p² 5f¹⁴ 6d¹⁰	14	2, 8, 18, 32, 32, 18, 4
115	McMoscovium	5	7s² 7p³ 5f¹⁴ 6d¹⁰	15	2, 8, 18, 32, 32, 18, 5
116	LvLivermorium	6	7s² 7p⁴ 5f¹⁴ 6d¹⁰	16	2, 8, 18, 32, 32, 18, 6
117	TsTennessine	7	7s² 7p⁵ 5f¹⁴ 6d¹⁰	17	2, 8, 18, 32, 32, 18, 7
118	OgOganesson	8	7s² 7p⁶ 5f¹⁴ 6d¹⁰	18	2, 8, 18, 32, 32, 18, 8

More on the periodic table

Interactive periodic tableAll 118 elements Charges & oxidation statesWhat ion each element forms Electron configurationsFull and shorthand notation Atomic mass tableIUPAC standard atomic weights ElectronegativityPauling values, every element Groups & periodsAll 18 groups explained Printable periodic tablesFree PDFs to print Element quizTest yourself on symbols

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Frequently Asked Questions

What are valence electrons?

Valence electrons are the electrons in an atom's outermost shell — the ones close enough to the surface to take part in bonding. Everything an element does chemically is essentially decided by how many it has and how many it needs to reach a full shell.

How do you find the number of valence electrons?

For main-group elements, read the group number. Groups 1 and 2 have 1 and 2 valence electrons. Groups 13 to 18 have the group number minus 10, so group 15 has 5 and group 17 has 7. Helium is the exception: it sits in group 18 but has only 2. Alternatively, count the electrons in the highest-numbered shell of the electron configuration.

How many valence electrons do transition metals have?

There is no single correct answer, which is why this table shows them as variable. Their outer s electrons and inner d electrons are close enough in energy that both can participate in bonding, and how many actually do depends on the compound. Iron uses two in Fe²⁺ and three in Fe³⁺.

What is the octet rule?

Most main-group atoms are most stable with eight valence electrons — a full s and p outer shell, the configuration the noble gases already have. Atoms gain, lose or share electrons to get there, which explains why group 1 forms +1 ions and group 17 forms −1 ions. Hydrogen and helium are content with two, and elements in period 3 and beyond can exceed eight.