Question

3 complete the table using your knowledge of the periodic table

Explanation:

Step1: Recall the relationship between atomic number, mass number, protons, electrons and neutrons

• For a neutral atom:
• Atomic number \(Z=\) Number of protons \(=\) Number of electrons.
• Mass number \(A=\) Number of protons \(+\) Number of neutrons.

Step2: Fill in the missing values

• For Na:
• Since it is a neutral atom, Number of electrons \(=\) Number of protons \( = 11\).
• For K:
• Number of neutrons \(=A - Z=39 - 19 = 20\).
• For Sr:
• Number of electrons \(=\) Number of protons \( = 38\).
• For Ca:
• Number of neutrons \(=A - Z=40 - 20 = 20\).
• For Sn:
• Mass number \(A=\) Number of protons \(+\) Number of neutrons \(=50 + 69 = 119\).
• For I:
• Number of electrons \(=\) Number of protons \( = 53\).
• Number of neutrons \(=A - Z=127 - 53 = 74\).

Answer:

Symbol	Atomic Number	Mass Number	Number of Protons	Number of Electrons	Number of Neutrons
K	19	39	19	19	20
Sr	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