Question

atoms of which element will contain 18 neutrons? *
18
ar
argon
39.95
9
f
fluorine
18.99
argan
fluorine
17
cl
chlorine
35.45
35
br
bromine
79.90
chlorine
bromine

Explanation:

Step1: Recall neutron calculation formula

The number of neutrons in an atom is calculated by the formula: \( \text{Number of neutrons} = \text{Atomic mass (approximate, using the mass number)} - \text{Atomic number} \). The atomic number is the top number on the element tile, and the mass number is approximately the atomic mass (the bottom number, we can use the whole number approximation for simplicity here).

Step2: Calculate neutrons for Argon

For Argon (\( \text{Ar} \)): Atomic number (\( Z \)) = 18, Atomic mass (approximate mass number) ≈ 40 (since 39.95 is close to 40). Number of neutrons = \( 40 - 18 = 22 \).

Step3: Calculate neutrons for Fluorine

For Fluorine (\( \text{F} \)): Atomic number (\( Z \)) = 9, Atomic mass ≈ 19 (since 18.99 is close to 19). Number of neutrons = \( 19 - 9 = 10 \).

Step4: Calculate neutrons for Chlorine

For Chlorine (\( \text{Cl} \)): Atomic number (\( Z \)) = 17, Atomic mass ≈ 35 (since 35.45 is close to 35). Number of neutrons = \( 35 - 17 = 18 \).

Step5: Calculate neutrons for Bromine

For Bromine (\( \text{Br} \)): Atomic number (\( Z \)) = 35, Atomic mass ≈ 80 (since 79.90 is close to 80). Number of neutrons = \( 80 - 35 = 45 \).

Answer:

Chlorine (the option with the Chlorine tile, or the third option in the layout: the one with atomic number 17, symbol Cl, name Chlorine, and atomic mass 35.45)