Question

complete the table using your knowledge of the periodic table

Explanation:

Step1: Recall atomic number property

Atomic number = number of protons.
For Na: Atomic number = 11.
For K: Atomic number = 19 (since number of electrons = 19, and in neutral atom, electrons = protons).
For the element with 38 protons: Atomic number = 38.
For F: Atomic number = 9 (since number of electrons = 9).
For Ca: Number of protons = 20 (atomic number = 20).
For Sn: Number of protons = 50 (atomic number = 50).
For I: Number of protons = 53 (atomic number = 53).

Step2: Recall mass number formula

Mass number = number of protons + number of neutrons.
For Na: Mass number = 11 + 12 = 23.
For K: Number of neutrons = 39 - 19 = 20.
For the element with 38 protons: Mass number = 38 + 50 = 88.
For F: Mass number = 9 + 10 = 19.
For Ca: Number of neutrons = 40 - 20 = 20.
For Sn: Mass number = 50 + 69 = 119.
For I: Number of neutrons = 127 - 53 = 74.

Step3: Recall electron - proton relation in neutral atom

In a neutral atom, number of electrons = number of protons.
For Na: Number of electrons = 11.
For the element with 38 protons: Number of electrons = 38.
For F: Number of protons = 9.
For Ca: Number of protons = 20.
For Sn: Number of protons = 50.
For I: Number of electrons = 53.

Answer:

Symbol	Atomic Number	Mass Number	Number of Protons	Number of Electrons	Number of Neutrons
K	19	39	19	19	20
Sr (since atomic number = 38)	38	88	38	38	50
F	9	19	9	9	10
Ca	20	40	20	20	20
Sn	50	119	50	50	69
I	53	127	53	53	74