Page 103 - Chemistry eBook

Base your answers to questions 51 through 53 on the information below and on your knowledge of chemistry.
When magnesium is ignited in air, the magnesium reacts with oxygen and nitrogen. The reaction between magnesium and nitrogen is represented by the unbalanced equation
below.
51 Balance the equation in your answer booklet for the reaction between magnesium and nitrogen, using the smallest whole-number coefficients. [1]
52 In the ground state, which noble gas has atoms with the same electron configuration as a magnesium ion? [1]
53 Explain, in terms of electrons, why an atom of the metal in this reaction forms an ion that has a smaller radius than its atom. [1]
Base your answers to questions 54 through 56 on the information below and on your knowledge of chemistry.
54 Identify the type of chemical bond in a molecule of the reactant. [1]
Mg(s) 􏰀 N2(g) → Mg3N2(s)
Sample Regents Questions
The balanced equation below represents a reaction. O2(g) 􏰀 energy → O(g) 􏰀 O(g)
June 2013 #52
Answer
55 In the space in your answer booklet, draw a Lewis electron-dot diagram of one oxygen atom. [1]
Answer: Ne
56 Explain, in terms of bonds, why energy is absorbed during this reaction. [1]
Explanation:
1. Let’s find the electron configuration of a magnesium ion:
a. Find the symbol for magnesium on Reffy, Table S (p. 10).
b. The symbol is Mg.
2. Find Mg on the Periodic Table on Reffy p. 9. The electron configuration of the Mg
atom is 2-8-2. But it forms a +2 ion, which means that it gives away 2 electrons.
Therefore, the electron configuration of the Mg ion is 2-8.
3. Now let’s look at Group 18 (noble gases) on the Periodic Table. Which element has an
electron configuration of 2-8? Ne.
UNIT 3: PERIODIC TABLE OF ELEMENTS © 103