AL MA’ARIFA INTL. PVT. SCHOOL
Grade-8/ science/ Term-1
Homework 3:
Chap 8/ Lesson 1/ Electrons and Energy Levels
Date: Sep. 28, 2021
1) Using the periodic table, complete the following chart. (6 points) (0.5
point each)
Remember, only the valence electrons are represented in electron dot diagram, not the total
number of electrons.
Element
Chemical
symbol
Potassium
K
Beryllium
Be
Neon
Ne
Sulfur
S
Total
number of
electrons
Number of
valence
electrons
Electron dot
diagram
2) Which element is the most chemically stable? Why? (1 point)
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3) Given the following neutral sodium atom. (3 points)
a.
Determine the mass number A (0.5 point)
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b.
Determine the atomic number (Z) (0.5 point)
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c.
Find the number of electrons and explain how you got it (1
points)
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d. Knowing that sodium atom belongs to group one, tell
whether it is stable or not. Explain your answer. (1 point)
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