Atomic structure Atomic Structure The structure of the atom The Ancient Greeks used to believe that everything was made up of very small particles. I did some experiments in 1808 that proved this and called these particles ATOMS: Dalton NEUTRON – neutral, same mass as proton (“1”) PROTON – positive, same mass as neutron (“1”) ELECTRON – negative, mass nearly nothing The Atom Nucleus Shell or Orbit Electron The Atom Hydrogen Proton Electron Hydrogen has one proton, one electron and NO neutrons The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons Mass andRelative atomic number Mass Relative Charge Particle Proton Neutron Electron 1 1 0 1 0 -1 MASS NUMBER = number of protons + number of neutrons SYMBOL PROTON NUMBER = number of protons (obviously) The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons The Atom Lithium Protons Neutrons Electrons The Atom Beryllium Protons Electrons Neutrons Beryllium has four electrons, four protons and five neutrons. The Atom Boron Protons Neutrons Boron has five electrons, five protons and six neutrons. Electrons The Atom Carbon Protons Neutrons Carbon has six electrons, six protons and six neutrons. Electrons The Atom Nitrogen Protons Electrons Neutrons Nitrogen has seven electrons, seven protons and seven neutrons. The Atom Oxygen Protons Electrons Neutrons Oxygen has eight electrons, eight protons and eight neutrons. The Atom Fluorine Protons Electrons Neutrons Fluorine has nine electrons, nine protons and ten neutrons. The Atom Neon Protons Neutrons Neon has ten electrons, ten protons and ten neutrons. Electrons The Atom Sodium Protons Electrons Neutrons Sodium has eleven electrons, eleven protons and twelve neutrons. How many protons, neutrons and electrons? Periodic table The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Mendeleev Horizontal rows are called PERIODS The Periodic Table Fact 1: Elements in the same group have the same number of electrons in the outer shell (this correspond to their group number) H He Li Be B C N O F Na M g Al Si P S Cl Ar K Ca Fe Ni C u Zn Ag Pt E.g. all group 1 metals have __ electron in their outer shell A u Ne Br Kr I Xe H g These elements have __ electrons in their outer shells These elements have __ electrons in their outer shell The Periodic Table Fact 2: As you move down through the periods an extra electron shell is added: Li Be Na M g K Ca E.g. Lithium has 3 electron Hin the configuration 2,1 He Sodium has 11 electrons inFethe Ni configuration 2,8,1 Pt Potassium has 19 electrons in the configuration __,__,__ C u Zn Ag A u B C N O F Al Si P S Cl Ar Br Kr I H g Ne Xe The Periodic Table Fact 3: Most of the elements are metals: H These elements are metals He Li Be B C N O F Na M g Al Si P S Cl Ar K Ca Fe Ni C u Zn Ag Pt A u This line divides metals from nonmetals Ne Br Kr I Xe H g These elements are non-metals The Periodic Table Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is how I thought of the periodic table in the first place. This is called PERIODICITY. H He Li Be B C N O F Na M g Al Si P S Cl Ar K Ca Fe Ni C u Zn Br Kr Ag 1 metals. They all: I E.g. consider the group 1) Are soft Pt A u H g 2) Can be easily cut with a knife 3) React with water Ne Xe Group 1 – The alkali metals Li Na K Rb Cs Fr Group 1 – The alkali metals Some facts… 1) These metals all have ___ electron in their outer shell 2) Reactivity increases as you go _______ the group. This is because the electrons are further away from the _______ every time a _____ is added, so they are given up more easily. 3) They all react with water to form an alkali (hence their name) and __________, e.g: Potassium + water 2K(s) + 2H2O(l) potassium hydroxide + hydrogen 2KOH(aq) + Words – down, one, shell, hydrogen, nucleus H2(g) Group 0 – The Noble gases He Ne Ar Kr Xe Rn Group 0 – The Noble gases Some facts… 1) All of the noble gases have a full outer shell, so they are very _____________ 2) They all have low melting and boiling points 3) They exist as single atoms rather then diatomic molecules 4) Helium is lighter then air and is used in balloons and airships (as well as for talking in a silly voice) 5) Argon is used in light bulbs (because it is so unreactive) and argon , krypton and neon are used in fancy lights Group 7 – The halogens F Cl Br I At Group 7 – The Halogens 1) Reactivity DECREASES as you go down the group Decreasing reactivity Some facts… (This is because the electrons are further away from the nucleus and so any extra electrons aren’t attracted as much). 2) They exist as diatomic molecules (so that they both have a full outer shell): Cl Cl 3) Because of this fluorine and chlorine are liquid at room temperature and bromine is a gas 1) Halogen + metal: The halogens – some reactions + + Na Cl Halogen + metal Cl Na ionic salt 2) Halogen + non-metal: H + Cl Halogen + non-metal Cl H covalent molecule - How shells fill • The first electron shell can only hold a maximum of two electrons. • The second electron shell can hold a maximum of eight electrons. • The third electron shell can also hold a maximum of eight electrons. • The fourth electron shell can also hold eight electrons. Consider an atom of Potassium: Electron structure Potassium has 19 electrons. These are arranged in shells… Nucleus The inner shell has __ electrons The next shell has __ electrons The next shell has __ electrons The next shell has the remaining __ electron Electron structure = 2,8,8,1 How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Hydrogen 1 electron 0 electron 0 electron 0 electron H Helium He 2 electron 0 electron 0 electron 0 electron How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Lithium Li 2 electron 1 electron 0 electron 0 electron Beryllium 2 electron 2 electron 0 electron 0 electron Be How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Boron B 2 electron 3 electron 0 electron 0 electron Carbon C 2 electron 4 electron 0 electron 0 electron How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Nitrogen N 2 electron 5 electron 0 electron 0 electron Oxygen O 2 electron 6 electron 0 electron 0 electron How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Fluorine F 2 electron 7 electron 0 electron 0 electron Neon Ne 2 electron 8 electron 0 electron 0 electron How the shells fill with electrons Element Shell 1 Sodium Na Shell 2 Shell 3 Shell 4 2 electron 8 electron 1 electron 0 electron Magnesium 2 electron 8 electron Mg 2 electron 0 electron How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Aluminium 2 electron 8 electron Al 3 electron 0 electron Silicon Si 4 electron 0 electron 2 electron 8 electron How the shells fill with electrons Element Shell 1 Shell 2 Shell 3 Shell 4 Phosphorus 2 electron 8 electron P 5 electron 0 electron Sulphur S 6 electron 0 electron 2 electron 8 electron How the shells fill with electrons Element Shell 1 Chlorine Cl Argon Ar Shell 2 Shell 3 Shell 4 2 electron 8 electron 7 electron 0 electron 2 electron 8 electron 8 electron 0 electron How the shells fill with electrons Element Shell 1 Potassium Calcium Ca Shell 2 Shell 3 Shell 4 2 electron 8 electron 8 electron 1 electron 2 electron 8 electron 8 electron 2 electron The First Twenty Elements • • • • • • • Hydrogen 1,0,0,0 Helium 2,0,0,0 Lithium 2,1,0,0 Beryllium 2,2,0,0 Boron 2,3,0,0 Carbon 2,4,0,0 Nitrogen 2,5,0,0 First 20 Elements continued • • • • • • • Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon 2,6,0,0 2,7,0,0 2,8,0,0 2,8,1,0 2,8,2,0 2,8,3,0 2,8,4,0 First 20 Elements continued • • • • • • Phosphorus Sulphur Chlorine Argon Potassium Calcium 2,8,5,0 2,8,6,0 2,8,7,0 2,8,8,0 2,8,8,1 2,8,8,2 The Alkali metals • Lithium, Sodium and Potassium have one electron in their outer shell and this is why they are found in group one of the periodic table. The Nobel gases • The Nobel gases have full outer shells and they are found in group 0 of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon. The Halogens • Fluorine, Chlorine, Bromine and Iodine are the Halogens and they all have seven electrons in their outer shell. This is why they are found in group 7 of the periodic table. Displacement • Fluorine can displace Chlorine, Bromine and Iodine. F Cl Br I Displacement • Chlorine can displace Bromine and Iodine but it cannot displace Fluorine Cl Br I F Displacement • Bromine can displace Iodine but it cannot displace Fluorine or Chlorine Br I F Cl Displacement • Iodine cannot displace Iodine Fluorine, Chlorine or Bromine I F Cl Br Fluorine reacts with sodium chloride. Which equation is correctly shows this reaction? • • • F2 + 2Na à 2NaF F + Na à NaF 2F + 2Na à 2NaF Which will displace? • • • • • • • 2NaF + Cl2 à Yes or No 2NaBr + Cl2 à Yes or No 2KI + I2 à Yes or No 2LiCl + I2 à Yes or No 2NaBr + I2 à Yes or No 2NaBr + F2à Yes or No Cl2 + 2NaBr à Yes or No Four factors affecting Reaction Rate Catalysts Concentration Temperature Surface Area Catalyst • A catalyst speeds up or slows down a reaction but does not get used up by the reaction. Temperature • If we increase the temperature of a reaction by 100C the rate will double this means the reaction will be complete in half the time. Concentration • If we increase the concentration of a reactant the number of particles increase that in turn increases the chance of a collision and initiates a chemical reaction. Surface area • The larger the particle size the smaller the relative area the slower the reaction. • The smaller the particle size the greater the relative surface area and the faster the reaction. Group 1 • Lithium, sodium and potassium are all in group 1. • They all have one electron in the outer shell. • They are all metals. • They react with group 7 to form metal halides. Group 7 • Fluorine ,Chlorine, Bromine and Iodine. • They all have 7 electrons in their outer shell. • They are all coloured. • They form metal halides with group 1 metals. Group 0 • • • • • • • These are the noble gases. They have complete electron shells. The electron shells are full. They are unreactive. They are inert. They do not react. They include, Helium, Neon, Argon, Krypton, Xenon and Radon Halogens Name Colour Fluorine Pale Yellow State Gas M.P. -220 B.P. -188 Chlorine Green Gas -101 -34 Bromine Brown Liquid -7 59 Iodine Solid 114 184 Slate grey Reactions • • • • • • Sodium and Chlorine react to form à Sodium Chloride. Iron and Chlorine react to form à Iron Chloride. 2Na + Cl2 à 2NaCl. Fe + Cl2 à FeCl2. Uses of the Halogens • Fluorine is put into water supplies to kill harmful bacteria and to help keep teeth healthy. • Chlorine is used in swimming pools to bacteria in the water. • Bromine is used in pesticides. Silver bromide is used in photography. • Iodine is an antiseptic on cuts and grazes.
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