Everything on the left of the periodic table is metal which loses and everything on the right
Side is a nonmetal which gains. You use the dots or the criss cross method either way works
But the criss-cross method is shorter. I prefer the dots just to get a visual idea.

Explore key information about the chemical elements through this periodic table
Group 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Period
1
1
H
1.008
2
He
4.0026
2
3
Li
6.94
4
Be
9.0122
5
B
10.81
6
C
12.011
7
N
14.007
8
O
15.999
9
F
18.998
10
Ne
20.180
3
11
Na
22.990
12
Mg
24.305
13
Al
26.982
14
Si
28.085
15
P
30.974
16
S
32.06
17
Cl
35.45
18
Ar
39.948
4
19
K
39.098
20
Ca
40.078
21
Sc
44.956
22
Ti
47.867
23
V
50.942
24
Cr
51.996
25
Mn
54.938
26
Fe
55.845
27
Co
58.933
28
Ni
58.693
29
Cu
63.546
30
Zn
65.38
31
Ga
69.723
32
Ge
72.63
33
As
74.922
34
Se
78.96
35
Br
79.904
36
Kr
83.798
5
37
Rb
85.468
38
Sr
87.62
39
Y
88.906
40
Zr
91.224
41
Nb
92.906
42
Mo
95.96
43
Tc
[97.91]
44
Ru
101.07
45
Rh
102.91
46
Pd
106.42
47
Ag
107.87
48
Cd
112.41
49
In
114.82
50
Sn
118.71
51
Sb
121.76
52
Te
127.60
53
I
126.90
54
Xe
131.29
6
55
Cs
132.91
56
Ba
137.33
*
71
Lu
174.97
72
Hf
178.49
73
Ta
180.95
74
W
183.84
75
Re
186.21
76
Os
190.23
77
Ir
192.22
78
Pt
195.08
79
Au
196.97
80
Hg
200.59
81
Tl
204.38
82
Pb
207.2
83
Bi
208.98
84
Po
[208.98]
85
At
[209.99]
86
Rn
[222.02]
7
87
Fr
[223.02]
88
Ra
[226.03]
**
103
Lr
[262.11]
104
Rf
[265.12]
105
Db
[268.13]
106
Sg
[271.13]
107
Bh
[270]
108
Hs
[277.15]
109
Mt
[276.15]
110
Ds
[281.16]
111
Rg
[280.16]
112
Cn
[285.17]
113
Uut
[284.18]
114
Fl
[289.19]
115
Uup
[288.19]
116
Lv
[293]
117
Uus
[294]
118
Uuo
[294] *Lanthanoids *
57
La
138.91
58
Ce
140.12
59
Pr
140.91
60
Nd
144.24
61
Pm
[144.91]
62
Sm
150.36
63
Eu
151.96
64
Gd
157.25
65
Tb
158.93
66
Dy
162.50
67
Ho
164.93
68
Er