1. Atoms, Molecules And Ions
Chapter 2
Atoms, Molecules
And Ions

4. Bromine has two naturally occurring isotopes. One has a mass of 78
Bromine has two naturally occurring isotopes. One has a mass of and an abundance of 50.69%. The other isotope has a mass of and an abundance of 49.31%.
Calculate the atomic weight of bromine.

5. Mass Spectrometer
An instrument that is used to determine the mass of an unknown element.
Will show the mass of all the isotopes of the element with their relative abundance.

6. Mass Spectrometer
The mass spectrum of Neon. The three isotopes of Neon are shown (20, 21 and 22). The major isotope has a mass of 20.

7. Coulomb’s Law The higher the charge – the stronger the attraction
The closer the ions – the stronger the attraction
p. 76

8. Fig. 2-21, p. 76

9. Which Compound has the higher melting point
and why?
Al2O3 or NaCl

10. Which Compound has the higher melting point
and why?
Al2O3 or NaCl
Al2O3 (melting point = 2072C) Al+3 and O-2
NaCl (melting point = 801C) Na+1 and Cl-1

11. Review Questions
Page 78
Answers are in the back of the book

12. Example 2.10, page 89 Br2 + O3 BrxOy
You react 1.25 grams of Br2 with excess O3 to form grams of BrxOy.
Determine the empirical formula for BrxOy
1.876 g – 1.25 g = g of O
You can use either g of O or O3 to solve the problem

13. Br: g Br mole Br mole Br
160 g Br mole Br2
= moles Br
O: g O mole O
16 g O
= moles O
O: g O mole O mole O
48 g O mole O3
= moles O

14. mol
Br:
= 1 O:
mol
mol
= 2.50
Br1O2.5
Br2O5