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Elements and Bonding youtube/watch?v=cL6I1O1YHH0

Yr 10 Science. Elements and Bonding http://www.youtube.com/watch?v=cL6I1O1YHH0. Atoms are rarely found by themselves, but instead join with other atoms . WHY DO ELEMENTS BOND?. This question is best answered by examining the Noble gases .

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Elements and Bonding youtube/watch?v=cL6I1O1YHH0

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  1. Yr 10 Science Elements and Bondinghttp://www.youtube.com/watch?v=cL6I1O1YHH0

  2. Atoms are rarely found by themselves, but instead join with other atoms.

  3. WHY DO ELEMENTS BOND? This question is best answered by examining the Noble gases. This “group” of atoms are inert (non-reactive). In fact, Helium, Neon and Argon never react with other atoms, or even themselves. This is because they have either 8 electrons in their outer shells, or a full outer shell.

  4. Noble gases have a very “stable” electron configuration. Other atoms will react with other atoms so they can achieve a similar electron configuration by either: • gaining or losing outer shell electrons (Ionic Bonding), or • sharing electrons (Covalent Bonding).

  5. Compounds are formed when different atoms react or join together. There are three main ways in which these atoms may join together: 1. Ionic bonding 2. Covalent bonding 3. Metallic bonding

  6. IONIC BONDING This occurs when a metal atom joins to a non-metal atom and electrons are transferred from the metal to the non- metal atom. e.g. NaCl Na+ + Cl- NaCl (2, 8) (2, 8, 8)

  7. Lets look closely at NaCl

  8. e.g. MgO

  9. Mg2+ + 2Cl- MgCl2 (2, 8) (2, 8, 8)

  10. IONIC BONDING Metalatoms lose their outer shell electrons to non-metal atoms. The metal atoms then become positive ions (cations). Non-metalatoms gain outer shell electrons from metal atoms to become negative ions (anions).

  11. The charge on an ion is called its valency. The ratio of metal atoms to non-metal atoms in an ionic compound is determined by each ions valency. **Handout valency sheet*** Naming Ionic Compound Activity

  12. Oppositely charged ions (positive cations & negative anions) are attracted to each other through electrostatic attraction.

  13. Bond Master Activity

  14. Activities – Writing Formula for Ionic Compounds

  15. Complete the following table

  16. cation anion Sodium Na+ Aluminium Al3+ Calcium Ca2+ Magnesium Mg2+ Lithium Li2+ Chloride Cl- Oxide O2- Fluoride F- Sulphide S2- Nitrate NO3- Sulfate SO42- Phosphate PO43- Hydrogen carbonate HCO3- cation anion Sodium chloride NaCl

  17. Sodium Na+ Aluminium Al3+ Calcium Ca2+ Magnesium Mg2+ Lithium Li+ Chloride Cl- Sodium chloride NaCl Aluminium chloride AlCl3 Calcium chloride CaCl2 Magnesium chloride MgCl2 Lithium chloride LiCl Oxide O2- Sodium oxide Na2O Aluminium oxide Al2O3 Calcium oxide CaO Magnesium oxide MgO Lithium oxide Li2O Fluoride F- Sodium fluoride NaF Aluminium fluoride AlF3 Calcium fluoride CaF2 Magnesium fluoride MgF2 Lithium fluoride LiF Sulfide S2- Sodium sulpfide Na2S Aluminium sulfide Al2S3 Calcium sulfide CaS Magnesium sulfide MgS Lithium sulfide Li2S Nitrate NO3- Sodium nitrate NaNO3 Aluminium nitrate Al(NO3)3 Calcium nitrate Ca(NO3)2 Magnesium nitrate Mg NO3)2 Lithium nitrate Li NO3 cation anion

  18. Sodium Na+ Aluminium Al3+ Calcium Ca2+ Magnesium Mg2+ Lithium Li+ Sulfate SO42- Sodium sulfate Na2SO4 Aluminium sulfate Al2 (SO4)3 Calcium sulfate CaSO4 Magnesium sulfate MgSO4 Lithium sulfate Li2SO4 Phosphate PO43- Sodium phosphate Na3PO4 Aluminium phosphate AlPO4 Calcium phosphate Ca 3(PO4)2 Magnesium phosphate Mg3(PO4)2 Lithium phosphate Li3(PO4) Hydrogen carbonate HCO3- Sodium Hydrogen carbonate NaHCO3 Aluminium Hydrogen carbonate Al(HCO3)3 Calcium Hydrogen carbonate Ca(HCO3)2 Magnesium Hydrogen carbonate Mg(HCO3)2 Lithium Hydrogen carbonate LiHCO3 cation anion

  19. COVALENT BONDING This occurs when two or more non-metal atoms join together by sharing electrons. e.g. H2O and CO2.

  20. Why do they share electrons? e.g. Consider a H2 molecule. Both H atoms need to gain electrons in order to achieve a complete outershell. They achieve this complete outershell by sharing pairsof electrons and this is called a covalent bond.

  21. A covalent bond is the electrostatic attraction between the negatively charged shared pair of electrons and the positive nucleus of each atom. The electrostatic attraction holds the atoms together and forms the molecule.

  22. Metallic Bonding Metallic bonding is the bond formed by positive ions surrounded by a sea of valence electrons. Delocalised Electrons –freely moving around the cations LATTICE Positive ions (CATIONS) – in fixed positions

  23. The electrostatic forcesof attraction between the positively charged cations and negatively charged electrons hold the lattice together. Animation of Metallic Bonding http://www.drkstreet.com/resources/metallicbonding-animation.swf

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