Period 4 of the Periodic Table

Period 4 of the periodic table has 18 elements, from Potassium (K) to Krypton (Kr). The period number usually equals the number of electron shells of the atom, and in this period the 4s, 3d and 4p subshells are filled. Moving left to right across a period, the atomic number increases and the atomic radius usually decreases.

Element list

Atomic no.	Symbol	Name	Atomic mass	Phase	Short configuration
19	K	Potassium	39.098	Solid	[Ar] 4s¹
20	Ca	Calcium	40.078	Solid	[Ar] 4s²
21	Sc	Scandium	44.956	Solid	[Ar] 3d¹ 4s²
22	Ti	Titanium	47.867	Solid	[Ar] 3d² 4s²
23	V	Vanadium	50.942	Solid	[Ar] 3d³ 4s²
24	Cr	Chromium	51.996	Solid	[Ar] 3d⁵ 4s¹
25	Mn	Manganese	54.938	Solid	[Ar] 3d⁵ 4s²
26	Fe	Iron	55.845	Solid	[Ar] 3d⁶ 4s²
27	Co	Cobalt	58.933	Solid	[Ar] 3d⁷ 4s²
28	Ni	Nickel	58.693	Solid	[Ar] 3d⁸ 4s²
29	Cu	Copper	63.546	Solid	[Ar] 3d¹⁰ 4s¹
30	Zn	Zinc	65.38	Solid	[Ar] 3d¹⁰ 4s²
31	Ga	Gallium	69.723	Solid	[Ar] 3d¹⁰ 4s² 4p¹
32	Ge	Germanium	72.63	Solid	[Ar] 3d¹⁰ 4s² 4p²
33	As	Arsenic	74.922	Solid	[Ar] 3d¹⁰ 4s² 4p³
34	Se	Selenium	78.96	Solid	[Ar] 3d¹⁰ 4s² 4p⁴
35	Br	Bromine	79.904	Liquid	[Ar] 3d¹⁰ 4s² 4p⁵
36	Kr	Krypton	83.798	Gas	[Ar] 3d¹⁰ 4s² 4p⁶

Frequently asked questions

How many elements are in period 4 of the periodic table?

Period 4 of the periodic table has 18 elements.

Which elements are in period 4?

The elements of period 4 run from Potassium to Krypton: Potassium (K), Calcium (Ca), Scandium (Sc), Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Germanium (Ge), Arsenic (As), Selenium (Se), Bromine (Br) and Krypton (Kr).