Write the symbol for every chemical element that has atomic number greater than 7 and atomic mass less than 24.0 u.

The elements and there symbols are as follows:

Oxygen ⇒ O

fluorine ⇒ F

Neon ⇒ Ne

Sodium ⇒ Na

The periodic table is arranged base on the atomic number of elements from left to right.

The atomic number is the number of proton of an element.

The atomic mass is the mass of an atom which is the average weight of an element form. it is measured in amu.

The symbols of elements with atomic numbers greater than 7 and atomic mass less than 24 amu are as follows.

Oxygen ⇒ O ⇒ atomic mass of 15.9994

fluorine ⇒ F⇒ atomic mass of 18.9984

Neon ⇒ Ne ⇒ atomic mass of 20.1797

Sodium ⇒ Na ⇒ atomic mass of 22.9897

The atomic number of Oxygen is 8 so, the numbering has to start from Oxygen. The atomic mass of sodium is approximately 23 amu so, the naming should stop there. The next chemical element(magnesium) has an atomic mass slightly greater than 24 amu

Check here for more information on periodic table:

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