Page 226 - Chemistry eBook

Answer all questions in this part.
Directions (51–65): Record your answers in the spaces provided in your answer booklet. Some questions may require the use of the 2011 Edition Reference Tables for Physical Setting/Chemistry.
Sample Regents Questions
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.
Mg(s) 􏰀 N2(g) → Mg3N2(s)
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]
June 2013 #51
Base your answers to questions 54 through 56 on the information below and on your knowledge of chemistry. The balanced equation below represents a reaction.
55 In the space in your answer booklet, draw a Lewis electron-dot diagram of one oxygen Explanation: atom. [1]
1. List the elements and number of elements on each from each side of the equation.
ergy is absorbed during this reaction. [1]
2. N has equal values on both sides. Don’t add any coefficient to the N atom. 3. There is 1 Mg on the right side, and 3 on the left side.
Add a coefficient of three to Mg on the left to make it 3Mg + N2 Mg3N2 4. Check
O (g) 􏰀 energy → O(g) 􏰀 O(g)
2
54 Identify the type of chemical bond in a molecule of the reactant. [1]
3Mg + N2 Mg3N2
Answer
Element
LEFT SIDE: Mg + N2
RIGHT SIDE: Mg3N2
Mg 56
Explain, in terms o
1
f bonds, why en
3
N
2
2
Element
LEFT SIDE: Mg + N2
RIGHT SIDE: Mg3N2
Are both sides equal?
Mg
1 x 3=3
3

N
2
2

225 © UNIT 6: MATH IN CHEMISTRY