1. CHEMISTRY November 13, 2014 ISOTOPES

2. SCIENCE STARTER Read the Science starter and annotate the text. Make sure to indicate in your annotation where you found the answer to the question/prompt. You have 7 minutes to complete the Science Starter. You are seated and silent

3. ANNOUNCEMENT MIDTERM – Next Friday

4. AIM/GUIDING QUESTION Give evidence to justify which isotope of oxygen can be found more in the glaciers of the polar region?

5. ISOTOPES Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.element – OR Isotopes are atoms of the same element that have the same atomic number but different mass numberselement

6. REMEMBER The number of protons in the nucleus of an atom is the Atomic Number of that atom and defines which type of atom it is, that is - which element the atom is a particle of.atomelement

7. MASS NUMBER The number of neutrons in the nucleus of an atom is the Mass Number (or "Atomic Mass") of the atom - the Atomic number of the atom

8. ISOTOPE NOTATIONS

9. ATOMIC MASS – The weighted average mass of all the naturally occurring isotopes of an element. – Need relative abundance and atomic mass to calculate the weighted average mass or average atomic mass

10. CALCULATING ATOMIC MASS Example: Carbon has two naturally occurring isotopes - 98.89% Carbon-12 and 1.108% Carbon-13 Solution: Convert the percentages to decimals and multiply the mass of each isotope by the relative abundance and add together. Percent x mass.9889 x 12 = 11.87.01108 x 13 = + 0.1440 Total: 12.01

11. ELECTRON WKSHT (4) Electron Configuration represents the distribution of all electrons for an element. – The electron configuration shown on the periodic table is at ground state. Adding the number shown in the electron configuration will give the number of electrons for an element. Example: 2-7-2 = 11 electrons