Write the Lewis dot structure of Argon. 2. Write Lewis dot structure for Boron. 3. Write Lewis dot structure for S
ion. 4. Which of the following compounds is ionic? (circle one answer) (a) ICI (b) CS
(c) CO
(d) CCl
(e) KF 5. Which pair of element would be most likely to form an ionic compound (a) F and Al (b) P and Br (c) Al and Rb (d) Zn and K (e) C and S 6. Write the correct formula for Copper(II) phosphate. 7. Write the chemical formula for Iron(II) nitrate.
The Correct Answer and Explanation is:
Lewis Dot Structure of Argon (Ar):
Argon (Ar) is a noble gas with an atomic number of 18. This means it has 18 electrons. In its Lewis dot structure, Argon has 8 electrons in its valence shell, which are arranged in pairs around the symbol Ar as follows:
makefileCopyEditAr: • •
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Argon is chemically inert because its valence shell is complete with 8 electrons, fulfilling the octet rule.
2. Lewis Dot Structure for Boron (B):
Boron (B) has an atomic number of 5, meaning it has 5 electrons. The Lewis dot structure for Boron shows that it has 3 valence electrons:
cssCopyEditB: • • •
Boron typically forms covalent bonds by sharing these 3 electrons to complete its octet when bonding with other atoms.
3. Lewis Dot Structure for Sulfide Ion (S²⁻):
Sulfur (S) has an atomic number of 16, so it has 6 valence electrons. The sulfide ion (S²⁻) has gained 2 electrons to form a stable 2⁻ charge, making its valence electron count 8. The Lewis dot structure for S²⁻ looks like:
makefileCopyEditS: • • •
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The 2 extra electrons fill the valence shell, completing the octet and giving the ion a full, stable configuration.
4. Which of the following compounds is ionic?
Answer: (e) KF
Explanation: Potassium (K) is a metal that easily loses its 1 electron to form a K⁺ ion, and Fluorine (F) is a non-metal that gains that electron to form an F⁻ ion. The opposite charges between K⁺ and F⁻ lead to an ionic bond, making KF an ionic compound.
5. Which pair of elements would be most likely to form an ionic compound?
Answer: (a) F and Al
Explanation: Fluorine (F) is a highly electronegative non-metal that readily gains 1 electron to form F⁻, while Aluminum (Al) is a metal that can lose 3 electrons to form Al³⁺. The large difference in electronegativity between these two elements makes them highly likely to form an ionic bond.
6. Correct Formula for Copper(II) Phosphate:
Copper(II) refers to copper in the +2 oxidation state (Cu²⁺), and phosphate is a polyatomic ion with the formula PO₄³⁻. To balance the charges, we need 3 Cu²⁺ ions for every 2 PO₄³⁻ ions. The correct formula is:
Cu₃(PO₄)₂
7. Chemical Formula for Iron(II) Nitrate:
Iron(II) refers to iron in the +2 oxidation state (Fe²⁺), and nitrate is a polyatomic ion with the formula NO₃⁻. To balance the charges, we need 1 Fe²⁺ ion for every 2 NO₃⁻ ions. The correct formula is:
Fe(NO₃)₂
In summary, the Lewis dot structures represent the valence electrons of elements and ions, while ionic compounds are formed through the transfer of electrons between a metal and a non-metal.
