Question

The table on the next page is made on the basis of the modern periodic table.write in it the electronic configuration of the first 20 elements below the symbol ,and write the valency (as shown in a separate box.)

Answer 1

Answer:

Name Atomic Number Electron Configuration

Period 1

Hydrogen 1 1s1

Helium 2 1s2

Period 2

Lithium 3 1s2 2s1

Beryllium 4 1s2 2s2

Boron 5 1s2 2s22p1

Carbon 6 1s2 2s22p2

Nitrogen 7 1s2 2s22p3

Oxygen 8 1s2 2s22p4

Fluorine 9 1s2 2s22p5

Neon 10 1s2 2s22p6

Period 3

Sodium 11 1s2 2s22p63s1

Magnesium 12 1s2 2s22p63s2

Aluminum 13 1s2 2s22p63s23p1

Silicon  14  1s2 2s22p63s23p2

Phosphorus 15 1s2 2s22p63s23p3

Sulfur 16 1s2 2s22p63s23p4

Chlorine 17 1s2 2s22p63s23p5

Argon 18 1s2 2s22p63s23p6

Period 4

Potassium 19 1s2 2s22p63s23p64s1

Calcium 20 1s2 2s22p63s23p64s2