1. C2 Smart Teach 1: Atoms, Ions and separation techniques

2. Atomic Structure Nucleus Contains: Protons and Neutrons Electron Shell Name of particle Relative mass Relative charge proton electron neutron 1 v. small 1 +1 0

3. Atomic Structure The mass number of an atom = the number of protons + neutrons. Na 23 11 mass number Atomic number The sodium atom above contains _______ protons and _____ neutrons. To calculate the number of neutrons = Big number – Small number 1112 The atomic number = the number of protons and the number of electrons.

4. HINT Sometimes you see elements written as this: Chlorine-35 35 is the mass number The atomic number can be found in the periodic table

5. Isotope The same element with the same number of protons but a different number of neutrons Relative atomic mass Average mass of all of the isotopes of an element relative to carbon-12

6. How do you calculate relative atomic mass? ((% x mass number) + (% x mass number) etc ) / 100 Calculate the relative atomic mass of magnesium ((80 x 24) + (10 x 25) + (10 x 26)) / 100 = 24.3

7. Atomic Structure Each shell can only hold a certain number of electrons 1 st shell can hold 2 electrons 2 nd shell can hold 8 electrons 3rd shell Holds 8 electrons Eg Oxygen has an atomic number of 8 Therefore it has 8 electrons Electron configuration 2.6

8. Periods: Tell you the number of shells an atom has Groups: Tell you the number of electrons in the outer shell of an atom The periodic table Metals are on LHS, boron is the only non metal in group 3

9. The periodic table The similarities and differences between the modern periodic table and Mendeleev's periodic table: SimilaritiesDifferences Elements arranged in groups Elements arranged in periods Elements with similar properties were put in the same group Metals and non metals were separated Mendeleev's the elements are arranged in order of atomic mass. In the modern periodic table they are ordered by atomic number. Mendeleev’s: had gaps

10. Ions Ions are electrically charged atoms or groups of atoms Mg 2+ CO 3 2- Cl - Atoms become ions when they loose or gain electrons.

11. Atoms form ions to get a full outer shell Example Lithium atom Lithium ion X X X - X X Group 1 atoms loose 1 electrons to become 1+ ions Group 2 atoms loose 2 electrons to become 2+ ions Group 6 atoms gain 2 electrons to become 2- ions Group 7 atoms gain 1 electron to form 1- ions

12. Making ionic compounds We can put two ions together to make a compound. The total charge of the molecule must be 0 e.g.: Sodium chloride: Na + and Cl - give NaCl Magnesium fluoride: Mg 2+ and F - gives MgF 2 Calcium hydroxide: Ca 2+ and OH - gives Ca(OH) 2

13. IONTEST Na + Sodium Flame testYellow Flame K + Potassium Flame testLilac Flame Ca 2+ Calcium Flame testRed Flame Cu 2+ Copper Flame testGreen Flame CO 3 2- Carbonate Add hydrochloric and pass gas through limewater Limewater turns cloudy SO 4 2- Sulfate Add a few drops of dilute HCl, shake, add a few drops of Barium Chloride White precipitate formed Cl - Chloride Add a few drops of dilute nitric acid, shake, add a few drops of silver nitrate White precipitate formed

14. Barium Meal Before some X-rays, patients have to swallow a suspension of barium sulfate, known as a ‘barium meal’. Explain why it is safe for these patients to swallow the barium sulfate? Because it is insoluble and does not get absorbed into the blood stream

15. Separation Techniques Describe how to separate two immiscible liquids Use a separating funnel, run off the lower liquid Describe how you would obtain a pure dry sample of an insoluble salt Filter, precipitate gets trapped in filter paper, wash with water, leave to dry Describe how to separate oxygen from nitrogen using fractional distillation of air Cool air to – 200 degrees C to make it into a liquid Carry out fractional distillation Allow to warm in column Remove nitrogen from top of column Remove oxygen from bottom of column