kids encyclopedia robot

Period (periodic table) facts for kids

Kids Encyclopedia Facts

A period in the periodic table is like a horizontal row of elements. Think of the periodic table as a big chart that organizes all the known chemical elements. Each row helps us understand how elements change as their atomic numbers increase.

The elements in a period are arranged by their atomic numbers, which means the number of protons in their atoms. As you move from left to right across a period, the atomic number goes up by one for each element.

Elements on the left side of a period are usually very metallic, like sodium or calcium. As you move to the right, the elements become less metallic and more nonmetallic, like oxygen or chlorine.

The first period has only 2 elements. The second and third periods each have 8 elements. The fourth and fifth periods each have 18 elements. The sixth and seventh periods each have 32 elements because they include the special f-block elements.

The Periodic Table Periods

Here is the standard periodic table, showing how elements are organized into periods and groups.

Group → 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Period ↓
1 1
H

2
He
2 3
Li
4
Be

5
B
6
C
7
N
8
O
9
F
10
Ne
3 11
Na
12
Mg

13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4 19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5 37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6 55
Cs
56
Ba
*
Lanthanides
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7 87
 Fr
88
Ra
*Actinides
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og
8 119
 Uue
120
 Ubn
*Superactinides

* Lanthanide Series 57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
** Actinide Series 89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
** Superactinide Series 121
Ubu
122
Ubb
123
Ubt
124
Ubq
125
Ubp
126
Ubh
127
Ubs
128
Ubo
129
Ube
130
Utn
131
Utu
132
Utb


Chemical Series of the Periodic Table

This section explains the different types of elements you see in the table, based on their properties and where they are located.

Superactinides


State at standard temperature and pressure

The color of the number (atomic number) above the element symbol shows what state the element is in at normal room temperature and pressure.

  • those in blue are gases
  • those in green are liquids
  • those in black are solid

Images for kids

kids search engine
Period (periodic table) Facts for Kids. Kiddle Encyclopedia.