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Understanding Atomic Model: Ionic and Covalent Bonds

Review of the atomic model, types of bonds (ionic and covalent), and compounds formed, with explanations of the octet rule, ionic charges, writing rules, transition metals, polyatomic ions, and naming conventions.

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Understanding Atomic Model: Ionic and Covalent Bonds

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  1. Review of Atomic Model

  2. Elements are pure substances containing one type of atom – found on the Periodic Table. The atomis the smallest part that retains all the properties of that element.

  3. Octet rule: atoms react to acquire a full outer shell: • Give away an e- to another atom. • Take an e- from another atom. • Share an e-with another atom. Ionic bond Covalent bond An ION is an atom that has lost or gained an electron. H : neutral atom H+ : positive cation H- : negative anion

  4. +1 +3 -3 -2 -1 +2 +4/-4 Remember: The number of the column is equal to the valence electron number. Know that and you figure out the number of electrons lost or gained – the ionic charge

  5. Ionic NaCl Covalent HCl A compound has different characteristic properties than the atoms which form it.

  6. Ionic Compounds Contain a METAL and a NON-METAL atom. Formed by TRANSFERING valence electrons to fill outer shell – octet rule. • A formula unit is the smallest unit of an ionic compound. Metal + Non-metal = ionic bonding

  7. Writing Rule 1: Write the symbol of the metallic element first. Beryllium combines with Chlorine + 2 - 1 Be Cl Rule 2: Place the combiningcapacityof one element as a subscript of the other element.

  8. Rule 3:Leave subscripts with a value of 1 out. Be Cl2 1 • Two Naming rules: • Write the full name of the metal ionfirst. • Name the non-metal iondropping the last • part of the name and adding the suffix “ide”. beryllium chlor ide

  9. Rule 4: Reduce the subscripts if possible. Magnesium combines with Sulfur + 2 - 2 Mg S MgS magnesium sulph ide

  10. Transition metals

  11. Transition metals can give away different numbers of electrons. To avoid confusion: Brackets are used to show how many electrons the Transition metal is giving away.

  12. Iron (II) chloride Iron (III) chloride + 2 - + 3 - 1 1 Fe Cl Fe Cl FeCl2 FeCl3

  13. Write the name of the ionic compound: +4 -2 Remember: Always look at the anion to see if it has been reduced. If it has, so has the metal. - + Pb O PbO 2 1 lead oxide (IV)

  14. Polyatomic Ions(poly = many) Groups of covalently bonded atoms that act as ionsin ionic bonding. Polyatomic ions function as one unit with one charge – lose or gain electrons. NEVER change the subscripts of polyatomic ions. Al(C2H3O2)3

  15. Write the name of the ionic compound: + - 1 Al C2H3O2 Al(C2H3O2) 3 aluminum acetate

  16. Ni(NO3)2 • magnesium sulfate • KMnO4 • iron (III) hydroxide • Ca(C2H3O2)2 • silver chromate • PbCO3 • tin (IV) sulfate • Na2HPO4 • ammonium nitrite nickel (II) nitrate MgSO4 potassium permanganate Fe(OH)3 calcium acetate Ag2CrO4 lead (II) carbonate Sn(SO4)2 sodium hydrogen phosphate NH4NO2

  17. Covalent Compound Contain two or more NON-METAL atoms. Formed by SHARING valence electrons to fill outer shell – octet rule. • A molecule is the smallest unit of a covalent compound. Non-metal + Non-metal = covalent bonding

  18. Step 1: firstnon-metal is named with a prefix to show the number of atoms. We do not use “mono” for the first non-metal. Step 2: secondnon-metal is named with a prefix AND with the “ide” ending. N O 2 4 nitrogen oxide di tetra dinitrogen tetroxide

  19. Writing formulas Step 1: Write the symbol of each element. Step 2: Use a subscriptto show the number of each type of atom given by the prefix. Do not reducecovalent formulas. di phosphorus oxide penta PO 2 5

  20. Does it have a metal? YES (ionic) Is it a transition? NO (covalent) Polyatomic • Find charges • Reverse Criss-cross • Don’t change ending • NO charges • NO criss-cross • Use prefixs • Ends in “ide” Fe(NO3)2 iron (II) nitrate NO YES OCl2 oxygen dichloride • Find charges • Criss-cross • Ends in “ide” • Find charges • Reverse Criss-cross • Use Brackets • Ends in “ide” MgCl2 magnesium chloride CuCl2 copper (II) chloride

  21. Many reactions are similar • Chemists have classified5 types of reactions BIG PICTURE IDEA: • If you know the reactants- you can guess the typeof reaction AND predict the products

  22. Synthesis A + B  C Decomposition C  A + B Single replacement A + BC  B + AC Double replacement AC + BD  AD + BC Carbon Combustion CxHy + O2  CO2 + H2O

  23. Diatomic Elements: Elements that are most commonly found in a covalent bond with itself. I Have No Bright Or Clever Friends I2H2N2Br2 O2Cl2F2

  24. Explain the difference between isotope and radioisotope • Explain average atomic mass using isotopes and their relative abundance Additional KEY Terms Radioactive decay Half-life

  25. The atomic number (Z) is the number of protons in the nucleus of an atom - identifies an element. The atomic mass (A) is the number of protonsplus the number of neutrons.

  26. Isotopes: Atoms with the but a different number of neutrons. same number of protons Hydrogen Atomic Mass = 1 Atomic Number = 1 Deuterium Atomic Mass = 2 Atomic Number = 1 Atomic mass is actually an average of isotopes of an element based on relativeabundance in nature.

  27. Mass spectrometer determines the mass of individual atoms or isotopes. Sends atoms through a magnetic field which bends their paths. The heavier the atom – the less it bends.

  28. Potassium isotopes: 1. 19 protons and 20 neutrons - mass number of 39 (potassium-39 39K) 2. 19 protons and 21 neutrons - mass number of 40 (potassium-40 40K) 3. 19 protons and 22 neutrons - mass number of 41 (potassium-41 41K)

  29. Magnesium exists as three isotopes in the world: 78.99% is 24Mg (23.985 μ) 10.00% is 25Mg (24.986 μ) 11.01% is 26Mg (25.982 μ) Calculate the average atomic mass of magnesium: (0.7899)(23.985 μ) = 18.95 μ + (0.1000)(24.986 μ) = 2.499 μ = 24.31 μ (0.1101)(25.982 μ) = 2.861 μ

  30. helium 5He 6He The nucleus of some isotopes are unstable and break apart over time - radioactivity.

  31. Radioisotopes - unstable nuclei releasing energy and/or particles. Release of energy is called radioactive decay. Atom may be converted into another isotope or a completely different element. Half-life - amount of time it takes for half the radioisotope to be converted into another particle.

  32. Many different types of decay: alpha decay, beta decay, gamma decay

  33. CAN YOU / HAVE YOU? • Explain the difference between isotope and radioisotope • Explain average atomic mass using isotopes and their relative abundance Additional KEY Terms Radioactive decay Half-life

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