Microsoft Word - Chemsheets GCSE 1002 (Structure of atoms 2).docx © www.CHEMSHEETS.co.uk 01-January-2016 Chemsheets GCSE 1002 Atom Atomic number Mass number Number of protons Number of neutrons Number...

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Microsoft Word - Chemsheets GCSE 1002 (Structure of atoms 2).docx © www.CHEMSHEETS.co.uk 01-January-2016 Chemsheets GCSE 1002 Atom Atomic number Mass number Number of protons Number of neutrons Number of electrons C!!" Cl!"!" F 9 19 Kr 84 36 B 5 5 Al 14 13 Au!"!"# Br 35 44 N!!" P!"!" Li 3 7 Ne 10 10 Ca 40 20 Be 5 4 Cl 17 18 W 110 74 U 92 146 Mo 42 96 Fe 56 26 Ni 28 30 I 127 53 STRUCTURE OF ATOMS 2 S.L.O.P Shed Loads of Practice! S.L.O.P Shed Loads of Practice! AQA Chemistry Unit 1 Atomic Structure & The Periodic Table Element Made from only one type of atom. Atom The smallest part of an element. Symbols One or two letters, first letter always capital, second letter always lower case e.g. Na Mg N Cl Fe Al Atomic Structure + + + + + ++ - - - - - - - Nucleus Electron Shell Proton Neutron 14 N 7 Mass number = Protons + Neutrons in the nucleus Atomic number = Protons = Electrons Atoms have no overall charge as the number of positive protons is equal to the number of negative electrons, their opposite charges cancel. Subatomic particle Location Relative mass Relative charge Proton Nucleus 1 +1 Neutron Nucleus 1 0 Electron Shells 1/2000th -1 The radius of the whole atom is about 0.1nm which is 1 x 10-10 m The radius of the nucleus is 1/10,000th that of the whole atom (1 x 10-14 m) , however it contains almost all of the atom’s mass. This means the atom is mostly empty space, except for its tiny nucleus. Electronic Structure • The negative electrons (x) occupy shells (energy levels) orbiting the nucleus of the atom. • The shells are filled from the lowest energy level (innermost/first shell) outwards. • The first (innermost) shell is full when it contains 2 electrons. • All other shells are full when they contain 8 electrons. Na x x x x x x x x x x x 23 Na 11 • Sodium (Na) has 11 electrons. • The first shell takes 2. • The next shell takes 8. • This leaves 1 for the outer shell. • Sodium is in group 1 of the periodic table, because it has 1 electron in its outermost shell. 2,8,1 How to work out the number of protons, neutrons and electrons in an atom: Isotopes – Versions of an element with a different number of neutrons. 12 C 6 vs. Protons = 6 Neutrons = 7 Electrons = 6 Protons = 6 Neutrons = 6 Electrons = 6 • Both are carbon as they both have 6 protons. • Therefore they have the same number of electrons (6). • They are isotopes of carbon as they contain a different number of neutrons 6 vs. 7. • This means they also have different atomic masses. You must state the numbers of each particle to gain the marks! 13 C 6 7 Li 3 • Protons = atomic number = 3 • Electrons = protons = 3 • Neutrons = atomic mass – atomic number 7 - 3 = 4 - Questions: Atomic Structure, Isotopes & Electronic Structure 1. Define the keyword atom. 2. Define the keyword element. 3. Draw a labelled diagram of a lithium atom, showing the protons, neutrons and electrons. 4. Explain what the mass number and atomic number tell us. 5. What is the mass of a proton? 6. What is the charge of a proton? 7. What is the mass of a neutron? 8. What is the charge of a neutron? 9. What is the mass of an electron? 10. What is the charge of an electron? 11. What fraction of the atomic radius, is the radius of the nucleus of an atom? 12. Give the number of protons (P+), neutrons (N) and electrons (e- ) for the following atoms: a) Na b) S c) Br d) Ca e) K f) F g) He h) O i) H j) Fe k) Zn l) Pb m) Li n) Al 13. Define the keyword isotope 14. Compare the similarities and differences between these two isotopes of oxygen (READ THE GUIDE!). 8 18O vs 8 16O 15. Compare the similarities and differences between these two isotopes of chlorine (READ THE GUIDE!). 17 37Cl vs 17 35Cl 16. What is the maximum number of electrons that can fill the first shell? 17. What is the maximum number of electrons that can fill the second shell? 18. Draw electronic structures for the following elements: a) H b) He c) Li d) C e) O f) S g) Ca h) Na i) Al j) S k) Ne 19. What group of the periodic table is oxygen in and why? 20. What group of the periodic table is magnesium in and why? 21. What group of the periodic table is chlorine in and why? 22. Why are the noble gases all in group 0? + Compound Two or more different elements bonded together. Reaction equations When different elements and/or compounds react with each other we write word and symbol equations. Word equation: Sodium + Chlorine  Sodium Chloride Symbol equation: 2 Na(s) + Cl2 (g)  2 NaCl (g) State symbols: Written in symbol equations to tell you the state of matter for each substance. (s) – Solid (l) – Liquid (g) – Gas (aq) – aqueous Balancing equations: The number of atoms of each element either side of the equation must be the same. 1. Count the number of atoms of each element on both sides. Al = 1 O = 2 Al = 2 O = 3 2. Find common denominators between the numbers and multiply so they match. __ Al + __ O2  __ Al2O3 Al = 1 O = 2 Al = 4 O = 3 __ Al + __ O2  __ Al2O3 = 4 x 2 = 6 x 4 = 4 x 3 = 6 3. Put the numbers you multiplied by in the equation’s gaps. Al = 1 O = 2 Al = 2 x 2 O = 3 __ Al + __ O2  __ Al2O3 = 4 x 2 = 6 x 4 = 4 x 3 = 6 4 3 2 Chemical Formulae Tell us how many atoms of each element a molecule or compound contains. Cl2 = 2 atoms of Cl bonded as molecule 2 Cl2 = 2 molecules of Cl2 Cl Cl Cl Cl Cl Cl Conservation of mass Mass is conserved, so it will be equal on both sides of a chemical equation. 4 Al + 3 O2  2 Al2O3 So five grams of aluminium and 3 grams of oxygen will give 8 grams of aluminium oxide! O O Ca CAl Al O O O O Al2O3 CaCO3 El em en t C o m p o u n d Development of the atomic model. New evidence has led to the atomic model changing over time. The Plum Pudding model of the atom: The Rutherford alpha particle experiment: Niels Bohr: Niels Bohr suggested that the electrons occupied energy levels (shells surrounding the atom). James Chadwick: James Chadwick discovered that the nucleus also contains neutrons. - - - - - - - - - When the electron was discovered, J.J Thomson suggested the atom was a positively charged sphere with negatively charged electrons embedded in it. Protons and neutrons were not included in the plum pudding as they had yet to be discovered. Ernest Rutherford tested the plum pudding model by firing positively charged alpha particles at gold atoms. Most of the alpha particles passed straight through, which suggested the atom was mostly empty space. A tiny proportion positive alpha particles scattered off in different directions, this suggests they collided with, and were repelled by, a tiny nucleus of positive charge. This new evidence proved that the plum pudding model was wrong. + α2+α2+α2+α2+α2+ α2+ α2+α2+α2+α2+ El em en t C o m p o u n d H Cl H Cl 2 HCl + 2 H2O M ix tu re o f C o m p o u n d s O H H O H H Mixture Two or more elements or compounds not chemically combined. The chemical properties of each substance in a mixture remain unchanged. Physical processes Physical processes can be used to separate mixtures. They do not result in a chemical reaction. Filtration Filtration is used to separate a mixture of a liquid and solid for example, sand and water. Crystallisation Crystallisation is used to obtain a solid form of a dissolved substance, for example getting solid salt from salty water. Distillation Distillation is used to separate mixtures of liquids with different boiling points. For example, ethanol and water. Chromatography Chromatography is used to separate mixtures containing colours, such as pen inks or food colourings. Filter funnel Filter paper Solid collects in filter paper Conical flask Liquid collects in conical flask Water evaporates Solution heated with Bunsen Burner Solution of dissolved substance Evaporating Basin Gauze Tripod Solid crystals remain Round bottomed flask Collection flask Water in Water out HEAT Mixture of liquids with different boiling points Evaporation Vapours rise up sill head into water condenser Thermometer 1. The mixture of liquids is heated. 2. The substance with the lowest boiling point evaporates first. 3. Its vapours rise up the sill head and are cooled in the water condenser. 4. The vapours condense into a liquid and collect in the