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Atomic structure

Atomic structure. Atomic Structure. ELECTRON – negative, mass nearly nothing. NEUTRON – neutral, same mass as proton (“1”). PROTON – positive, same mass as neutron (“1”).

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Atomic structure

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  1. Atomic structure

  2. Atomic Structure

  3. ELECTRON – negative, mass nearly nothing NEUTRON – neutral, same mass as proton (“1”) PROTON – positive, same mass as neutron (“1”) The Ancient Greeks believed that everything was made up of very small particles. In 1808 John Dalton proved this and called these particles ATOMS: The structure of the atom Dalton

  4. The Atom Electron Nucleus Shell or Orbit

  5. The Atom Hydrogen Proton Electron Hydrogen has one proton, one electron and NO neutrons

  6. The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons

  7. The Atom Helium Proton Electron Neutron Helium has two electrons, two protons and two neutrons

  8. The Atom Lithium Electrons Protons Neutrons

  9. The Atom Beryllium Electrons Protons Neutrons Beryllium has four electrons, four protons and five neutrons.

  10. The Atom Boron Electrons Protons Neutrons Boron has five electrons, five protons and six neutrons.

  11. The Atom Carbon Electrons Protons Neutrons Carbon has six electrons, six protons and six neutrons.

  12. The Atom Nitrogen Electrons Protons Neutrons Nitrogen has seven electrons, seven protons and seven neutrons.

  13. The Atom Oxygen Electrons Protons Neutrons Oxygen has eight electrons, eight protons and eight neutrons.

  14. The Atom Fluorine Electrons Protons Neutrons Fluorine has nine electrons, nine protons and ten neutrons.

  15. The Atom Neon Electrons Protons Neutrons Neon has ten electrons, ten protons and ten neutrons.

  16. The Atom Sodium Electrons Protons Neutrons Sodium has eleven electrons, eleven protons and twelve neutrons.

  17. MASS NUMBER = number of protons + number of neutrons 4 He SYMBOL 2 PROTON NUMBER = number of protons (obviously) Mass and Atomic Number

  18. Describing Atoms • Atomic Number = number of protons • In a neutral atom, the # of protons = the # of electrons • Atomic Mass= the number of protons + the number of neutrons

  19. Isotopes • The number of protons for a given atom never changes. • The number of neutrons can change. • Two atoms with the same number of protons but different numbers of neutrons are called isotopes. • Isotopes have the same atomic # • Isotopes have different atomic Mass #’s

  20. Isotopes

  21. The periodic table arranges all the elements in groups according to their properties. Vertical columns are called GROUPS Mendeleev Periodic table Horizontal rows are called PERIODS

  22. These elements have __ electrons in their outer shell E.g. all group 1 metals have __ electron in their outer shell These elements have __ electrons in their outer shells 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)

  23. E.g. Lithium has 3 electron in the configuration 2,1 Sodium has 11 electrons in the configuration 2,8,1 Potassium has 19 electrons in the configuration __,__,__ The Periodic Table Fact 2: As you move down through the periods an extra electron shell is added:

  24. These elements are metals This line divides metals from non-metals These elements are non-metals The Periodic Table Fact 3: Most of the elements are metals:

  25. E.g. consider the group 1 metals. They all: • Are soft • Can be easily cut with a knife • React with water The Periodic Table Fact 4: (Most important) All of the elements in the same group have similar PROPERTIES. This is called PERIODICITY.

  26. Group 1 – The alkali metals

  27. 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.

  28. Potassium + water potassium hydroxide + hydrogen 2K(s) + 2H2O(l) 2KOH(aq) + H2(g) 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: Words – down, one, shell, hydrogen, nucleus

  29. Group 17(7A) – The Halogens

  30. Decreasing reactivity Cl Cl Group 17(7A) – The Halogens Some facts… 1) Reactivity DECREASES as you go down the group (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): 3) Because of this fluorine and chlorine are liquid at room temperature and bromine is a gas

  31. Group 18 (8A)– The Noble Gases

  32. Group 18(8A) – 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 3) Helium is lighter then air and is used in balloons and airships (as well as for talking in a silly voice) • Argon is used in light bulbs (because it is so unreactive) and argon , krypton and neon are used in fancy lights

  33. The Nobel gases • The Nobel gases have full outer shells and they are found in group 18 (8A) of the periodic table. Helium, Neon, Argon, Krypton, Xenon and Radon.

  34. 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.

  35. 39 K 19 Nucleus Consider an atom of Potassium: Electron structure Potassium has 19 electrons. These are arranged in shells… 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

  36. Ions • An atom that carries an electrical charge is called an ion • If the atom loses electrons, the atom becomes positively charged (because the number of positively charged protons will be more the number of electrons= cation). • If the atom gains electrons, the atom becomes negatively charged (because there are more negative charges than positive = anion).

  37. Ions • The number of protons does not change in an ion. • The number of neutrons does not change in an ion. • So, both the atomic number and the atomic mass remain the same.

  38. Ions This atom has lost an electron. Now it has one more proton than electron. One more proton means one more positive charge. This makes the total charge of the atom POSITIVE. This atom has gained an electron. Now it has one less proton than electron. One less proton means one less positive charge. This makes the total charge of the atom NEGATIVE.

  39. H H Cl Cl metal + halogen ionic salt Na + - Cl Na Cl non-metal + halogen covalent molecule The halogens – some reactions 1) Metal + halogen: + 2) Non-metal+ halogen +

  40. Fluorine reacts with sodium to produce – sodium florideWhich equation correctly shows this reaction? • F2 + 2Na  2NaF • F + Na  NaF • 2F + 2Na  2NaF

  41. 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.

  42. Group 7 • Fluorine ,Chlorine, Bromine and Iodine. • They all have 7 electrons in their outer shell. • They form metal halides with group 1 metals.

  43. 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.

  44. Reactions • Sodium and Chlorine react to form  • Sodium Chloride. • Iron and Chlorine react to form  • Iron Chloride. • 2Na + Cl2  2NaCl. • Fe + Cl2  FeCl2.

  45. 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.

  46. Group 18 (8A) • 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

  47. How many protons, neutrons and electrons? Review 1 11 16 H B O 1 5 8 23 35 238 Na Cl U 11 17 92

  48. THE END

  49. Four factors affecting Reaction Rate

  50. Catalyst • A catalyst speeds up or slows down a reaction but does not get used up by the reaction.

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