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Bell Work

Bell Work. Write the electron configuration for an element with an atomic number of 23. Then, draw the electrons in their proper orbitals. . Physical Science – Lecture 38. Introduction to Bonding. Valence Electrons. 1A = 1 valence electron 2A = 2 valence electrons

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Bell Work

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  1. Bell Work • Write the electron configuration for an element with an atomic number of 23. Then, draw the electrons in their proper orbitals.

  2. Physical Science – Lecture 38 Introduction to Bonding

  3. Valence Electrons • 1A = 1 valence electron • 2A = 2 valence electrons • 3A = 3 valence electrons • 4A = 4 valence electrons • 5A = 5 valence electrons • 6A = 6 valence electrons • 7A = 7 valence electrons • 8A = 8 valence electrons

  4. Electron Dot Structures • Indicates the number of electrons surrounding an element in the outer energy level. • Represents valence shell electrons

  5. Valence Electrons • Equal to the group number • Represents electrons in the outer energy level • Elements want valence electrons equal to noble gases (group 8A)

  6. Octet Rule • All elements want 8 electrons in their outer shell. • They want 8 valence electrons to be complete. • Only exception – Hydrogen and Helium only want 2.

  7. Becoming a Noble Gas • Elements can lose or gain electrons to become “noble like”. • Loss of electrons = cation (+ charge) • Gain of electrons = anion (- charge) • How do we remember each one?

  8. Cations • Elements lose electrons to become positive • Positive charge comes from an abundance of protons. • For every electron lost, elements becomes +1.

  9. Example • If 2 electrons are lost, element becomes +2. • Mg → Mg2+ + 2e-

  10. Anions • Elements gain electrons to become negative • Negative charge comes from an abundance of electrons. • For every electron gained, elements becomes -1.

  11. Example • If 3 electrons are gained, element becomes -3. • N + 3e- → N3-

  12. 1+ Cations • H+ Hydrogen • Li+ Lithium • Na+ Sodium • K+ Potassium • Ag+ Silver • NH4+ Ammonium • Also, all group 1 elements

  13. +2 Cations • Mg2+ Magnesium • Ca2+ Calcium • Ba2+ Barium • Sn2+ Tin(II) • Pb2+ Lead(II) • Mn2+ Manganese(II) • Fe2+ Iron(II) or ferrous • Hg22+Mercury (I) or mercurous • Co2+ Cobalt(II) • Ni2+ Nickel(II) • Cu2+ Copper(II) • Zn2+ Zinc • Hg2+ Mercury(II) or mercuric • Also all group 2 elements.

  14. +3 Cations • Al3+ Aluminum • Cr3+ Chromium(III) • Fe3+ Iron(III) or ferric • Also all group 3 elements.

  15. -1 Anions • F- Fluoride • Cl- Chloride • Br- Bromide • I- Iodide • OH- Hydroxide • CN- Cyanide • NO3- Nitrate • NO2- Nitrite • MnO4- Permanganate • Also all group 7 elements.

  16. -2 Anions • O2- Oxide • S2- Sulfide • SO3 2- Sulfite • SO4 2- Sulfate • CO3 2- Carbonate • CrO4 2- Chromate • Cr2O7 2- Dichromate • Also all group 6 elements.

  17. -3 Anions • PO43- Phosphate • Also all group 5 elements.

  18. Forming Cations/Anions • Group 1 (1A) = forms +1 Cations • Group 2 (2A) = forms +2 Cations • Group 13 (3A) = forms +3 Cations • Group 14 (4A) = forms +4 Cations or -4 Anions • Group 15 (5A) = forms -3 Anions • Group 16 (6A) = forms -2 Anions • Group 17 (7A) = forms -1 Anions • Group 18 (8A) = Already Noble-like

  19. Why is this useful?

  20. BONDING!

  21. How to Bond. • Elements can share or take/receive electrons to make them have 8 outer electrons.

  22. Two types of Bonding • Covalent – between two non-metals. They share electrons. • A metal will give its electrons to a non-metal to have a completed octet in the octet below its valence shell (becoming a cation). • A non-metal will take electrons from a metal to fulfill its outer valence shell (becoming an anion).

  23. Ionic – between a metal and a non-metal or a cation and an anion. They steal or give away electrons to each other. • Two non-metals will share electrons to make them both think that they have a full outer shell.

  24. Ionic Example

  25. Bonding

  26. Covalent Example

  27. Covalent Bonding • Must designate through the name how many of each compound are present (since there are no charges to cancel out).

  28. Example – Carbon dioxide

  29. Forming Ionic Compounds • Ionic compounds come from ions. • The charges cancel out

  30. Compounds • Form together in whole number ratios • Formula unit = lowest whole number ratio

  31. Practice • Can Mg and F form a compound? • What will this compound look like?

  32. How many valence electrons are in Mg? • What is it’s charge when it becomes noble like? • What is the electron dot structure?

  33. How many valence electrons are in F? • What is it’s charge when it becomes noble like? • What is the electron dot structure?

  34. How many of each do we need to balance the charges? • What will the new electron dot structure look like when they bond?

  35. Electron dot structure of Mg and F

  36. Writing Chemical Formulas • Cation always goes first • Anion always goes last • Numbers of each written as subscripts

  37. Chemical Formula of Mg and F

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