Answer:
The first 50 elements along with their valences are given below :
1. Hydrogen = 1
2. Helium = 0
3. Lithium = 1
4. Beryllium = 2
5. Boron = 3
6. Carbon = 4
7. Nitrogen = 3
8. Oxygen = 2
9. Fluorine = 1
10. Neon = 0
11. Sodium = 1
12. Magnesium = 2
13. Aluminium = 3
14. Silicon = 4
15. Phosphorus = 3
16. Sulphur = 2
17. Chlorine = 1
18. Argon = 0
19. Potassium = 1
20. Calcium = 2
21. Scandiun = 3
22. Titanium = 3
23. Vanadium = 4
24. Chromium = 3
25. Manganese = 4
26. Iron = 2
27. Cobalt = 2
28. Nickel = 2
29. Copper = 2
30. Zinc = 2
31. Gallium = 3
32. Germanium = 4
33. Arsenic = 3
34. Selenium = 2
35. Bromine = 1
36. Krypton = 0
37. Rubidium = 1
38. Strontium = 2
39. Yttrium = 3
40. Zirconium = 4
41. Niobium = 3
42. Molybdenum = 3
43. Technetium = 7
44. Ruthenium = 4
45. Rhodium = 3
46. Palladium = 4
47. Sliver = 1
48. Cadmium = 2
49. Indium = 3
50. Tin = 4
<u>Note</u> :
An element like Iron, copper can have more than one valencies.
The answer to this question would be: alkaline earth metal
Alkali earth metal is the second column group of the periodic table. In this group, the element has 2 extra electrons in their outer cells. That is why most of this metal has 2+ charge.
Their neighbor is the alkali metal which was the first column of the periodic table. The name is similar so don't confused and mix them each other.
Explanation:
Tc - 99 is technetium 99.
It is a radioactive element that decays spontaneously. It has a half-life of 211,000 years and decays to stable ruthenium.
- On the periodic table, it has an atomic number of 43;
Mass number = 99
Atomic number = number of protons = number of electrons in atom
Number of protons in Tc is 43
electron is 43
Mass number = number of protons + number of neutrons
Number of neutrons = mass number - number of protons = 99-43 = 56
learn more:
Atomic number brainly.com/question/2057656
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