1. 4.3 Atomic #, Mass #, Atomic Mass & Isotopes

2. Atomic Number  What are the 3 subatomic particles?  Which of the subatomic particles identifies an element? PROTONS! Each element has a different number of protons, thus making it unique. PROTONS! Each element has a different number of protons, thus making it unique.  Atomic Number: the # of protons in the nucleus of an atom  The # of protons is equal to the # of electrons. Why? Why?

3. Atomic Number

4. Problems:  How many protons are in Al? 13 13  How many protons are in V? 23 23  How many electrons are in Copper? 29 29

5. Mass Number  In an atom, where is most of the mass located? In the nucleus In the nucleus  What subatomic particles are in the nucleus? Protons & Neutrons Protons & Neutrons  Mass number is the mass found in the nucleus mass number: # of protons + # of neutrons  You can find mass number by looking at the shorthand notation.

6. Shorthand Notation  Used to show the mass # and atomic number of an element.  14 is the mass #  7 is the atomic #  N is the symbol for nitrogen

7. Shorthand Notation  Can also be written as: element-mass # Examples Nitrogen-14, Nitrogen-15, Nitrogen- 16 Examples Nitrogen-14, Nitrogen-15, Nitrogen- 16  How many neutrons are in each of the above elements?  What is the shorthand notation for gold-197?

8. Try These  What is the mass number of 40 Ca? 40 40  How many neutrons are in germanium-73? 41 41  How many protons, electrons & neutrons does zinc-65 have? Protons: 30 Protons: 30 Electrons: 30 Electrons: 30 Neutrons: 35 Neutrons: 35

9. Isotopes  Think about pizza…..  Isotopes are similar forms of the same element.  More specifically, isotopes have the same number of protons, but different number of neutrons.  If neutrons change, what else changes? Mass Mass

10. Atomic Mass  We must take in account all of the isotopes in order to get an accurate mass.  The mass on the PT is a weighted average of all the naturally occurring isotopes of an element.  This is called atomic mass.

11. Carbon Isotopes  Carbon has several isotopes  The two most naturally occurring isotopes are carbon-12 and carbon-13  This means C-12 and C-13 account for all of the atomic mass.  So how do we calculate atomic mass?

12. Carbon Isotopes  Carbon-12 Mass: 12.000 amu Mass: 12.000 amu (amu: atomic mass unit) (amu: atomic mass unit) Abundance: 98.89% Abundance: 98.89% How many neutrons are in carbon-12? How many neutrons are in carbon-12?  Carbon-13 Mass: 13.003 amu Abundance: 1.11% How many neutrons are in carbon-13?

13. Carbon Isotopes  Atomic mass=(mass of isotope 1 x abundance) + (mass of isotope 2 x abundance) + (mass of isotope 3 x abundance)  (12.000 x.9889) + (13.001 x.0111)=12.011 amu  Find this value on your PT!  Try #23 on page 117

14. Hydrogen Isotopes  Hydrogen-1  Name: protium  Hydrogen-2  Name: deuterium 1e 1 p 0 n 1e 1 p 1 n

15. Hydrogen Isotopes  Hydrogen-3  Name: tritium 1e 1 p 2 n  Try # 20 on page 113