Question

q1 chemistry: do now: for each multiple - choice question below, use strong annotations to find the correct answer. the word \isoelectronic\ is used for two different ions or atoms that have the same number of electrons. iso - means equal and electronic means electron structure. apply this term in the questions below. 1. which ion is isoelectronic to mg+2? a. ca+2 b. cl−1 c. na+1 d. s−2 2. which pair has identical electron configurations? a. s−2 and cl−1 b. s0 and ar0 c. k0 and na+1 d. cl−1 and k0 3. how do you know? 4. why might it be important to identify isoelectronic ions/atoms? 5. which set of symbols represents atoms with valence electrons in the same electron shell? a. ba,br,bi b. sr,sn,i c. o,s,te d. mn,hg,cu for each of the pairs of ions/neutral atoms below, determine the difference in total electrons between the two, and match one of the answer choices below. a. difference of 0 electrons b. difference of 2 electrons c. difference of 3 electrons d. difference of 8 electrons 6. __ ne and cl−1 7. be+2 and h+1 8. c+4 and he 9. __ si−4 and p

Explanation:

Step1: Find electrons in Mg²⁺

Magnesium (Mg) has atomic number 12. Mg²⁺ has 12 - 2=10 electrons.

Step2: Analyze each option for question 1

• a. Ca²⁺: Calcium has atomic number 20. Ca²⁺ has 20 - 2 = 18 electrons.
• b. Cl⁻: Chlorine has atomic number 17. Cl⁻ has 17+1 = 18 electrons.
• c. Na⁺: Sodium has atomic number 11. Na⁺ has 11 - 1=10 electrons.
• d. S²⁻: Sulfur has atomic number 16. S²⁻ has 16 + 2=18 electrons. So for question 1, the answer is c.

Step3: Analyze electron - configurations for question 2

• a. S²⁻ has 18 electrons (16 + 2) and Cl⁻ has 18 electrons (17+1). Their electron - configurations are identical.
• b. S⁰ has 16 electrons and Ar⁰ has 18 electrons.
• c. K⁰ has 19 electrons and Na⁺ has 10 electrons.
• d. Cl⁻ has 18 electrons and K⁰ has 19 electrons. So for question 2, the answer is a.

Step4: Answer question 3

I know because I calculated the number of electrons in each ion/atom based on their atomic numbers and the charge on the ion.

Step5: Answer question 4

Identifying isoelectronic ions/atoms is important because they have similar chemical and physical properties due to the same electron - structure.

Step6: Analyze valence - shell electrons for question 5

• a. Ba is in period 6, Br is in period 4, Bi is in period 6.
• b. Sr, Sn, I are all in period 5. Their valence electrons are in the same electron shell.
• c. O is in period 2, S is in period 3, Te is in period 5.
• d. Mn is in period 4, Hg is in period 6, Cu is in period 4. So for question 5, the answer is b.

Step7: Calculate electron differences for questions 6 - 9

• 6. Ne has 10 electrons and Cl⁻ has 18 electrons. The difference is 18 - 10 = 8 electrons (D).
• 7. Be²⁺ has 4 - 2 = 2 electrons and H⁺ has 1 - 1 = 0 electrons. The difference is 2 - 0=2 electrons (B).
• 8. C⁴⁺ has 6 - 4 = 2 electrons and He has 2 electrons. The difference is 2 - 2 = 0 electrons (A).
• 9. Si⁻⁴ has 14+4 = 18 electrons and P has 15 electrons. The difference is 18 - 15 = 3 electrons (C).

Answer:

1. c. Na⁺
2. a. S⁻² and Cl⁻¹
3. I calculated the number of electrons in each ion/atom based on their atomic numbers and the charge on the ion.
4. They have similar chemical and physical properties due to the same electron - structure.
5. b. Sr, Sn, I
6. D. Difference of 8 electrons
7. B. Difference of 2 electrons
8. A. Difference of 0 electrons
9. C. Difference of 3 electrons