Question

1. fill in the following table.

isotope symbol	atomic number	mass number	number of protons	number of neutrons
$_{9}^{18}f$
	16		15

Explanation:

Step1: Recall atomic - related concepts

The atomic number ($Z$) is equal to the number of protons. The mass number ($A$) is the sum of the number of protons and neutrons. The isotope symbol is written as $_{Z}^{A}X$, where $X$ is the chemical symbol of the element.

For the isotope $_{9}^{18}F$:

Step2: Calculate the number of neutrons

Number of neutrons = Mass number - Number of protons. Given $A = 18$ and $Z=9$ (number of protons), so number of neutrons $=18 - 9=9$.

For the third - row where number of protons is 15 and atomic number is 16:

Step3: Identify the element

The element with atomic number 16 is sulfur (S).

Step4: Calculate the mass number

Mass number = Number of protons+Number of neutrons. Given number of protons = 15 and number of neutrons = 16, so mass number $=15 + 16=31$. The isotope symbol is $_{15}^{31}P$ (since the element with 15 protons is phosphorus).

Answer:

Number of Neutrons	Number of Protons	Mass Number	Atomic Number	Isotope Symbol
16	15	31	15	$_{15}^{31}P$