1. Starter Activity How are these Easter eggs like atoms? How are these eggs different?

2. Name that element Discuss with the person next to you What is the element above? EXPLAIN your answers 2 minutes To be able to recall some examples of isotopes

3. Each isotope reacts with oxygen to form water, however unlike hydrogen and deuterium, tritium is radioactive. Isotopes of Hydrogen H 1 1 H 1 2 H 1 3 1 proton, 1 electron, 0 neutrons 1 proton, 1 electron, 1 neutron 1 proton, 1 electron, 2 neutrons To be able to recall some examples of isotopes To be able to describe the physical properties for the isotopes of hydrogen

4. Defining Isotopes Individually write a definition for isotope (1 minute) In pairs share your definitions and come up with an agreed definition for isotope (1 minute) To be able to define isotope Atoms of the same element with a different number of neutrons

5. Mini Plenary How are these eggs like isotopes?

6. Other Isotopes Carbon 12 and Carbon 14 Hydrogen, Deuterium and Tritium Chlorine 35 and Chlorine 37 Nitrogen 13, Nitrogen 14 and Nitrogen 15 To be able to recall some examples of isotopes Key Question If their number of protons and electrons are the same, are their chemical and physical properties the same?

7. Properties Sometimes extra neutrons can make the nucleus unstable, so its radioactive. Different isotopes of the same element can have different physical properties, e.g. Density. Different isotopes of the same element ALWAYS the same chemical properties because their reactions depend on their electron structure. To be able to describe the physical properties for the isotopes of hydrogen

8. Mini Plenary Do all of these isotopes react with oxygen? Explain your answer

9. What is up with Chlorine? Where do we get 35.45 from? Relative atomic mass takes into consideration all the isotopes of the element and their abundance. To be able to calculate Relative atomic mass Chlorine has 2 isotopes Chlorine 35 and Chlorine 37 75% of one mole of atoms are Cl-35 25% of one mole of atoms are Cl-37 General Formula Ar = (Ar of isotope 1 x Abundance of isotope 1) + (Ar of isotope 2 x Abundance of isotope 2) 100 Chlorine Ar = (35 x 75) + (37 x 25) = 35.5 100

10. Have a go yourself Nitrogen N 14 = 99.64%N15 = 0.36% Carbon C 12 = 98.93%C13 = 1.07% Potassium K39 = 93.2%K41 = 6.8% Boron B10 = 19.9%B11 = 81.1% Silicon Si28 = 92.2% Si29 = 4.68 Si 30 = 3.08% To be able to calculate Relative atomic mass 14.0036 12.0107 39.136 10.911 28.0972

11. Mini Plenary The number of protons in an atom is called it number. The relative mass of a neutron compared with a proton is. Compared with the protons and neutrons have almost no mass. The total number and neutrons in an atom is called its number. Atoms of an element which have different numbers of neutrons are called. Electrons isotopesprotons mass atomic one atomic one Electrons protons mass isotopes