H Chem: Chapter 4 - Isotopes

H Chem: Chapter 4 - Isotopes

by Jennifer Haycraft

​Ions

• ​an atom that has either gained or lost one or more electrons.

• ​# electron do NOT = # protons

• ​Only electrons change; NEVER protons

• ​Gaining electrons = negatively-charged ion (ANION)

• ​Losing electrons = positively-charged ion (CATION)

Open Ended

$$\ _{\ \ 7}^{14}\ N\ ^{-3}$$  

How many protons?

How many neutrons?

How many electrons?

​Ions and Net Charge

• ​The net charge is the balance between the positive protons and the negative electrons.

• ​An atom has 20 protons and 18 electrons: Net Charge = +2

• ​An atom has 4 protons and 6 electrons: Net Charge = -2

​Average Atomic Mass

Open Ended

Carbon has two isotopes.  Carbon-12 is 98.89% abundant and carbon-13 is 1.11% abundant.  Carbon-12 has a mass of 12.000000 amu and carbon-13 has a mass of 13.00335 amu.  What is the average atomic mass?

Open Ended

The element chlorine has two common isotopes, chlorine-35 (75.63% abundant) and chlorine-37 (24.37% abundant).  The atomic masses of these two isotopes are 34.968 amu and 36.956 amu, respectively.  What is the average atomic mass of the element chlorine?

Open Ended

Lithium has an average atomic mass of 6.941 amu. Lithium has two common isotopes lithium-6 and lithium-7. If the atomic masses of these two isotopes are 6.0151 amu and 7.0160 amu, respectively. What are the percentage abundances of each of these isotopes?