Explain arrangement of electrons in atoms of elements having atomic number from 1 to 20.
Answers
Atomic Number Name of the Element Electronic Configuration
1 Hydrogen (H) 1s1
2 Helium (He) 1s2
3 Lithium (Li) [He] 2s1
4 Beryllium (Be) [He] 2s2
5 Boron (B) [He] 2s2 2p1
6 Carbon (C) [He] 2s2 2p2
7 Nitrogen (N) [He] 2s2 2p3
8 Oxygen (O) [He] 2s2 2p4
9 Fluorine (F) [He] 2s2 2p5
10 Neon (Ne) [He] 2s2 2p6
11 Sodium (Na) [Ne] 3s1
12 Magnesium (Mg) [Ne] 3s2
13 Aluminium (Al) [Ne] 3s2 3p1
14 Silicon (Si) [Ne] 3s2 3p2
15 Phosphorus (P) [Ne] 3s2 3p3
16 Sulphur (S) [Ne] 3s2 3p4
17 Chlorine (Cl) [Ne] 3s2 3p5
18 Argon (Ar) [Ne] 3s2 3p6
19 Potassium (K) [Ar] 4s1
20 Calcium (Ca) [Ar] 4s2
Explanation:
Element Atomic no. Electronic configuration
1.Hydrogen 1 1
2.Helium 2 2
3.Lithium 3 2,1
4.Beryllium 4 2,2
5.Boron 5 2,3
6.Carbon 6 2,4
7.Nitrogen 7 2,5
8.Oxygen 8 2,6
9. Fluorine 9 2,7
10. Neon 10 2,8
11.Sodium 11 2,8,1
12.Magnesium 12 2,8,2
13.Aluminum 13 2,8,3
14.Silicon 14 2,8,4
15.Phosphorus 15 2,8,5
16.Sulphur 16 2,8,6
17.Clorine 17 2,8,7
18.Argon 18 2,8,8
19.Potassium 19 2,8,8,1
20.Calcium 20 2,8,8,2
Elements Valency (Octet) Symbol
1.Hydrogen 1 H
2.Helium 0 He
3.Lithium 1 Le
4.Beryllium 2 Br
5.Boron 3 B
6.Carbon 4 C
7.Nitrogen 3 N
8.Oxygen 2 O
9. Fluorine 1 F
10. Neon 0 Ne
11.Sodium 1 Na
12.Magnesium 2 Mg
13.Aluminum 3 Al
14.Silicon 4 Si
15.Phosphorus 3 P
16.Sulphur 2 S
17.Clorine 1 Cl
18.Argon 0 Ar
19.Potassium 1 K
20.Calcium 2 Ca
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