Question

write elements symbols atomic number atomic mass electronic configuration and valency of 1 to 20 Modern Periodic Table​

Answer 1

Answer:

first 20 elements atomic masses

Explanation:

it is rounded off and can be used in ordinary calculation

Answer 2

The electronic configuration, atomic number, atomic mass and valency of the first 20 elements with atomic numbers are as follows-

• The element with the atomic number 1 is H and has the atomic mass of 1. Its valency is 1. Its electronic configuration is-

${1s}^{1}$

• The element with the atomic number 2 is He and has the atomic mass of 4. Its valency is 0. Its electronic configuration is-

${1s}^{2}$

• The element with the atomic number 3 is Li and has an atomic mass of 7. Its valency is 1. Its electronic configuration is-

${1s}^{2} {2s}^{1}$

• The element with the atomic number 4 is Be and has the atomic mass of 9. Its valency is 0. Its electronic configuration is-

${1s}^{2} {2s}^{2}$

• The element with the atomic number 5 is B and has an atomic mass of 11. Its valency is 3. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{1}$

• The element with the atomic number 6 in C has an atomic mass of 12. Its valency is 4. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{2}$

• The element with the atomic number 7 is N and has an atomic mass of 14. Its valency is 3. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{3}$

• The element with atomic number 8 is Oxygen (O) and has an atomic mass of 16. Its valency is 2. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{4}$

• The element with the atomic number 9 is F and has an atomic mass of 19. Its valency is 1. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{5}$

• The element with the atomic number 10 is Ne and has an atomic mass of 20. Its valency is 0. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6}$

• The element with the atomic number 11 is Na and has an atomic mass of 23. Its valency is 1. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{1}$

• The element with the atomic number 12 is Mg and has an atomic mass of 24. Its valency is 2. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2}$

• The element with the atomic number 13 is Al and has an atomic mass of 27. Its valency is 3. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{1}$

• The element with the atomic number 14 is Si and has an atomic mass of 28. Its valency is 4. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{2}$

• The element with the atomic number 15 is P and has an atomic mass of 31. Its valency is 3. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{3}$

• The element with atomic number 16 is S and has an atomic mass of 32 Its valency is 2. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{4}$

• The element with the atomic number 17 is Cl and has an atomic mass of 35. Its valency is 1. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{5}$

• The element with the atomic number 18 is Ar and has an atomic mass of 36. Its valency is 0. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{6}$

• The element with atomic number 19 is K and has an atomic mass of 39. Its valency is 1. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{6} {4s}^{1}$

• The element with the atomic number 20 is Ca and has an atomic mass of 40. Its valency is 2. Its electronic configuration is-

${1s}^{2} {2s}^{2} {2p}^{6} {3s}^{2} {3p}^{6} {4s}^{2}$