Chapter 2 Questions in Class PDF

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Atomic Symbols

The symbol for tin is: (a)  Ti (b)  Tn (c)  T (d)  Sn (e)  Si

Tin has the symbol Sn (Latin: stannum). Tinstone (tin dioxide) mined from Cornwall. elements.vanderkrogt.net

Nuclide Symbol: An Example Example: What is the shorthand notation for the nuclide chlorine-35?

(a)

(b)

(c)

17 35 35 17

17

Cl

A X Z

Cl

Cl

35

What is the atomic symbol for chlorine?

Cl

What is the atomic number (Z) for chlorine?

17

What is the mass number (A) for chlorine-35?

35

Chlorine-35

35 17

Cl

Average Atomic Masses What is the average atomic mass of an element that has the following distribution of naturally occurring isotopes? ISOTOPE

ISOTOPIC MASS (amu) 34.97 36.97

#1 #2

PERCENTAGE ABUNDANCE 75.78 % 24.22 %

The average atomic mass of the element is: (a)  35.97 amu (b)  35.45 amu (c)  36.17 amu (75.78 x 34.97) + (24.22 x 36.97) 100 = 35.45 amu

The element is chlorine and the isotopes are 35Cl and 37Cl.

Naming Ionic Compounds What is the most appropriate name of the following ionic compound? BaO (a)  barium oxide (b)  barium(I) oxide (c)  barium(II) oxide Barium(I) oxide is incorrect because the oxidation state of barium is +2. Barium(II) is not strictly incorrect, but since barium has only one oxidation state, it is not necessary to specify it.

The Formula: Examples Example: What is the formula of the ionic compound of Mg2+ and N3-? The common multiple of the charges is 6 so we need three Mg2+ and two N3-. The resulting formula is: 3 x (+2) = 6

2 x (-3) = -6

Mg3N2 Example: What is the formula of the ionic compound of Ca2+ and PO43-? The common multiple of the charges is 6 so we need three Ca2+ and two PO43-. The resulting formula is: 3 x (+2) = 6

2 x (-3) = -6

Ca3(PO4)2

Chemical Formulas for Ionic Compounds What is the chemical formula for potassium carbonate?

(a)  (b)  (c)  (d) 

KCO3 K2CO3 KCO2 K2CO2

Potassium only forms one ion, i.e. K+. The carbonate ion is CO32-. The ions K+ and CO32- form K2CO3

Name the following molecular compounds

Nitrogen dioxide

Boron Trifluoride

Chlorine monofluoride

Hydrogen selenide

Balance the Following Equation

O2 +

PCl3

POCl3

(a)

O2 +

PCl3

POCl3

(b)

O2 + 2 PCl3

2 POCl3

(c)

2 O2 +

PCl3

2 POCl3

Balance the Following Equation

P4 +

N2 O

(a)

4 P4 +

6 N2 O

P4O6 + 6N2

(b)

2 P4 + 12 N2O

8 P4O6 + 12N2

6 N2 O

P4O6 + 6N2

(c)

P4 +

P4O6 +

N2

Balance the Following Equation

As4S3 +

O2

As4O3 + SO2

(a) 2 As4S3 +

9 O2

2As4O3 + 6SO2

As4S3 +

O2

As4O3 + SO2

4 As4S3 + 18 O2

4 As4O3 + 6SO2

(b)

(c)...