1. Atomic Structure Topic 2.1

2. 2.1.1 State the position of protons, neutrons and electrons in the atom. 2.1.2 State the relative masses and relative charges of protons, neutrons and electrons 5x10 -4

3. 2.1.3 Define the terms mass number (A), atomic number (Z) and isotopes of an element.

4. Examples! State the atomic number and atomic mass of the following. 2 4 He 6 12 C 6 14 C hmmm...but why does Carbon have 2 masses?

5. They are ISOTOPES! Isotopes are atoms of the same element with the same number of protons, but have a different number of neutrons So the same atomic number, but different atomic mass 6 12 C 6 14 C

6. 2.1.4 Deduce the symbol for an isotope given its mass number and atomic number. Example: A sample of Carbon is found to have a mass of 15 atomic mass unit (AMU). Write the standard notation for this element. Hint: use your periodic table!

7. More examples... Two samples of silver are found. One sample has an average mass of 107 AMU, the other 109 AMU. Write the standard notation for both.

8. What about electrons? Atomic number = number of protons Atomic mass = number of protons + neutrons If neutral, protons = electrons If an ion, look at the charge and deduce the difference between protons and electrons

9. 2.1.5 Calculate the number of protons, neutrons and electrons in atoms and ions from the mass number, atomic number and charge Let’s use the previous example to start! 107 47 Ag 109 47 Ag Protons: Neutrons: Electrons:

10. Ion Examples 12 24 Mg +2 Protons: Neutrons: Electrons: Remember, it’s a CATION and should have less electrons than protons!!!

11. Ion Examples 35 81 Br - Protons: Neutrons: Electrons: Remember, it’s an ANION and should have more electrons than protons!!!

12. 2.1.6 Compare the properties of the isotopes of an element. Chemical properties will remain the same, however, physical properties will differ. ie) Obviously the mass, but also density, rate of diffusion, melting/boiling point...

13. 2.1.7 Discuss the uses of radioisotopes Radioisotopes are radioactive isotopes They have several important uses in our society There are both good and bad impacts made by these isotopes

14. RadioCarbon Dating Carbon-14 exists in a set ratio with Carbon-12 When the organism dies, C-14 decays, but C-12 does not The percentage of C-14 decreases as the age of the dead organism increases. This percentage is used to estimate the age of the organism.

15. Homework 1) Research one of the following radioisotopes: Iodine-125 or Iodine-131 or Cobalt-60 2) Complete the Atomic Structure Worksheet