Step-by-step explanation:
Atomic number of sodium is 11 and it is a group 1 element. Hence, it is most reactive in nature.
Some properties of sodium are as follows.
- It is one of the most chemically reactive metals.
- When it is not stored properly, sodium reacts explosively with air or water.
Atomic number of calcium is 20 and it is a group 2 element. Some properties of calcium are as follows.
- Calcium is less reactive than sodium, but it is more reactive than most metals.
- Both sodium and calcium are always found as compounds in nature, and they are never present as elements.
Atomic number of iron is 26 and it is a d-block element. Therefore, it is also known as transition element.
Some properties of iron are as follows.
- Iron also reacts with oxygen, but it does so over a period of time.
- When not protected by a coating then iron will gradually turn to rust, a compound of iron and oxygen.
Atomic number of gold is 79 and it is also a transition element. A property of gold is that it does not react easily with other substances.