Starter Activity

1. Starter Activity Draw what you think an atom looks like and for extra CHALLENGE, label each part of the atom with its name and charge

2. Combined Science (1-9): RadioactivityAtomic Models

3. Objectives: • 6.1 Describe an atom as a positively charged nucleus, consisting of protons and neutrons, surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus • 6.2 Recall the typical size (order of magnitude) of atoms and small molecules • 6.3 Describe the structure of nuclei of isotopes using the terms atomic (proton) number and mass (nucleon) number and using symbol format • 6.4 Recall that the nucleus of each element has a characteristic positive charge, but that isotopes of an element differ in mass by having different numbers of neutrons • 6.5 Recall the relative masses and relative electric charges of protons, neutrons, electrons and positrons • 6.6 Recall that in an atom the number of protons equals the number of electrons and is therefore neutral • 6.17 Describe how and why the atomic model has changed over time including reference to the plum pudding model and Rutherford alpha particle scattering leading to the Bohr model

4. Draw a line under last lesson’s work and write today’s title in your book... 20/06/2017 c/w The Atomic Model

5. FLASHBACK FLASHBACK: Jot down the order of the electromagnetic spectrum from smallest to longest wavelength and provide the use and danger of three divisions

6. Atomic Structure An atom consists of a combination of protons, neutronsand electrons You’ll cover this in greater detail later but protons and neutrons come under the grouping of nucleons as they are found in the nucleus (the core) The much smaller electrons are found orbiting in shells around the nucleus

7. Atomic Structure You will need to know the relative mass and charge of each of these particles. QUESTION: Looking back at the atom above, what would be the OVERALL/TOTAL charge on this atom?

8. Size Comparison People don’t often realise how small atoms and the particles that make them up actually are! An interesting fact is that: “there are more atoms in a grain of sand than there are grains of sand on the Earth” Just let that sink in…

9. 4 He 2 What does the image below show?

10. MASS NUMBER (A) = number of protons + number of neutrons 4 SYMBOL of the element He ATOMIC NUMBER (Z) = number of protons 2 Elements (unique atoms) How many protons, neutrons and electrons does this element have?

11. How many protons, neutrons and electrons do each of these elements have (if uncharged)? 1 11 16 H B O 1 5 8 23 35 238 Na Cl U 11 17 92

12. 16 O 17 18 O O 8 8 8 What are the similarities and differences in these elements?

13. 16 O 17 18 O O 8 8 8 Each isotope has 8 protons – this is what “makes” it oxygen. Isotopes of Elements ISOTOPES = atoms of the same element that have a different number of neutrons. Look at your Periodic Table and choose another element, invent two isotopes for that element

14. What happens if an atom loses electrons? Overall Charge: Neutral Positive (ion) Remember, as an electron is negatively charged, by losing some of this negativity, the atom has become overall more positive

15. What could cause an atom to be ionised (i.e. lose or gain an electron)?

16. Explore What can cause an atom to lose electrons?

17. There are three types of radiation that can create ions – called IONising Radiation gamma beta alpha This is smaller as it is simply one electron This is the largest particle and is made of two protonsand two neutrons (aka a helium nucleus) This has no mass as it is an EM wave but it has a lot of energy Where do they come from?

18. You will be given 60 SECONDS to memorise this….. Atomic Theory Timeline Democritus -400BC Existence of atoms first suggested. Atoms can be determined by their mass and combine to make compounds Dalton 1803 Plum pudding model. Negative electros are scattered throughout a positive ‘dough’ Thomson 1906 Nuclear model. Charge mostly concentrated in a central core. Most of the space is empty with electrons orbiting 1911 Rutherford 1913 Electrons limited to specific energy orbits they can jump between Bohr

19. You can speed up the motor by: • Increasing the current • Increasing the length of wire (number of turns) • Increasing the magnetic field Now attempt to recreate it! Atomic Theory Timeline Democritus -400BC Existence of atoms first suggested. Atoms can be determined by their mass and combine to make compounds Dalton 1803 Plum pudding model. Negative electrons are scattered throughout a positive ‘dough’. Disproved by rutherford Thomson 1906 Nuclear model. Charge mostly concentrated in a central core. Most of the space is empty with electrons orbitting 1911 Rutherford 1913 Electrons limited to specific energy orbits they can jump between Bohr

20. Old Theories- Plum Pudding A scientist named Thomson new that atoms were made up of smaller particles and that these were a combination of different charges. His model was like a plum pudding, where a big cloud of positive charge (dough) contained smaller negatively charged particles (raisins)

21. Alpha Particle Scattering Experiment

22. Alpha Particle Scattering Experiment Rutherford (Geiger and Marsden) • Fired Alpha Particles at a thin piece of gold foil • Different deflection angles proved the structure of atoms Most of atom is empty space 0-10° Deflection Central concentration of charge 10-90° Deflection Most mass is concentrated in centre 90-180° Deflection

23. Nuclear Structure MINI quiz • Label the Atomic Mass • Label the Atomic/Proton Number • Explain what an Isotope is • Which quantity is labelled ‘Z’ and which is labelled ‘A’? • Explain why the atomic mass of chlorine is 35.5

24. Exam Question Describe the structure of the atom with reference to charge and relative mass and size. How has our model of the atom changed over the years?(6 marks)

25. Describe the structure of the atom with reference to relative charge, mass and size. How has our model of the atom changed over the years?(6 marks) Mark Scheme • Atoms consist of smaller particles • Nucleus contains protons and neutrons • Electrons orbit the nucleus • Reference to relative masses (1, 1, 0) • Reference to relative charge (+1, -1, 0) • Reference to (Thompson’s) plum pudding model • Alpha Particle Scattering Experiment aimed alpha particles at gold nuclei/thin gold foil • Different deflection angles AND an explanation of the result (proved a centralised mass and charge)