Question

iodine
126.905
atomic # =
atomic mass =
mass number =

of protons =

of neutrons =

of electrons =

argon
39.948
atomic # =
atomic mass =
mass number =

of protons =

of neutrons =

of electrons =

h
1.008
atomic # =
atomic mass =
mass number =

of protons =

of neutrons =

of electrons =

Explanation:

Step1: Recall atomic number definition

Atomic number = number of protons. For Iodine (I), atomic number is 53. For Argon (Ar), atomic number is 18. For Hydrogen (H), atomic number is 1.

Step2: Identify atomic mass

Given in the element box. For Iodine, atomic mass = 126.905. For Argon, atomic mass = 39.948. For Hydrogen, atomic mass = 1.008.

Step3: Determine mass number

Mass number is the closest whole - number to atomic mass. For Iodine, mass number = 127. For Argon, mass number = 40. For Hydrogen, mass number = 1.

Step4: Calculate number of neutrons

Number of neutrons = mass number - number of protons. For Iodine, number of neutrons = 127 - 53=74. For Argon, number of neutrons = 40 - 18 = 22. For Hydrogen, number of neutrons = 1 - 1 = 0.

Step5: Find number of electrons

In a neutral atom, number of electrons = number of protons. For Iodine, number of electrons = 53. For Argon, number of electrons = 18. For Hydrogen, number of electrons = 1.

Answer:

Iodine:
Atomic # = 53
Atomic Mass = 126.905
Mass Number = 127

of Protons = 53

of Neutrons = 74

of Electrons = 53

Argon:
Atomic # = 18
Atomic Mass = 39.948
Mass Number = 40

of Protons = 18

of Neutrons = 22

of Electrons = 18

Hydrogen:
Atomic # = 1
Atomic Mass = 1.008
Mass Number = 1

of Protons = 1

of Neutrons = 0

of Electrons = 1