What are the first 20 elements? What is its mass number? Trick to find mass number.
Element - Symbol (Mass number).
1. Hydrogen - H (1)
2. Helium - He (4)
3. Lithium - Li (7)
4. Beryllium - Be (9)
5. Boron - B (11)
6. Carbon - C (12)
7. Nitrogen - N (14)
8. Oxygen - O (16)
9. Fluorine - F (19)
10. Neon - Ne (20)
11. Sodium - Na (23)
12. Magnesium - Mg (24)
13. Aluminium - Al (27)
14. Silicon - Si (28)
15. Phosphorus - P (31)
16. Sulfur -S (32)
17.Chlorine - Cl (35.5)
18. Argon - Ar (40)
19. Potassium - K (39)
20. Calcium - Ca (40)
How to find the mass number: (Just a trick, only for first 20 elements )
1. If atomic number (Z) is odd, then the mass number is
(Z x 2) +1
2. If atomic number (Z) is even, then the mass number is
(Z x 2) + 0
3. The bold elements are exceptional from the given tricks to find mass number
4. The atomic number is the S.no (here).
