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Ionic Bonding …electrons are transferred. Guiding Questions? What is that? How do we figure out what the chemical formula is? What does it mean to be.

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Presentation on theme: "Ionic Bonding …electrons are transferred. Guiding Questions? What is that? How do we figure out what the chemical formula is? What does it mean to be."— Presentation transcript:

1 Ionic Bonding …electrons are transferred

2 Guiding Questions? What is that? How do we figure out what the chemical formula is? What does it mean to be "free of chemicals"?

3 Keeping Track of Electrons  The electrons responsible for the chemical properties of atoms are those in the outer energy level.  Valence electrons - The s and p electrons in the outer energy level.  Core electrons -those in the energy levels below.

4 Keeping Track of Electrons  Atoms in the same column  Have the same outer electron configuration.  Have the same valence electrons.  Easily found by looking up the group number on the periodic table.  Group 2A - Be, Mg, Ca, etc.-  2 valence electrons

5 Electron Dot diagrams AA way of keeping track of valence electrons. HHow to write them WWrite the symbol. PPut one dot for each valence electron DDon’t pair up until they have to X

6 The Electron Dot diagram for Nitrogen l Nitrogen has 5 valence electrons. l First we write the symbol. N l Then add 1 electron at a time to each side. l Until they are forced to pair up.

7 Mg Write the electron dot diagram for  Na  Mg CC OO FF  Ne  He 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 1s22s22p21s22s22p2 1s22s22p41s22s22p4 1s22s22p51s22s22p5 1s22s22p61s22s22p6 1s21s2 Na C O F He Ne

8 Electron Configurations for Cations  Metals lose electrons to attain noble gas configuration.  They make positive ions.  If we look at electron configuration it makes sense.  Na 1s 2 2s 2 2p 6 3s valence electron  Na + 1s 2 2s 2 2p 6 -noble gas configuration

9 Ca +2 Electron Dots For Cations  Metals will have few valence electrons  These will come off  Forming positive ions Ca s22s22p63s21s22s22p63s2

10 Electron Configurations for Anions  Nonmetals gain electrons to attain noble gas configuration.  They make negative ions.  If we look at electron configuration it makes sense.  S 1s 2 2s 2 2p 6 3s 2 3p valence electrons  S -2 1s 2 2s 2 2p 6 3s 2 3p 6 -noble gas configuration. (anions)

11 Electron Dots For Anions  Nonmetals will have many valence electrons.  They will gain electrons to fill outer shell. P P -3

12 Stable Electron Configurations  All atoms react to achieve noble gas configuration.  Noble gases have two s and six p electrons.  Eight valence electrons.  Also called the octet rule. Ar

13 Ionic Bonding  Anions and cations are held together by opposite charges.  Ionic compounds are called salts.  Simplest ratio is called the formula unit.  The bond is formed through the transfer of electrons.  Electrons are transferred to achieve noble gas configuration.

14 Ionic Bonding NaCl transfer of electron + - NaCl

15 Ionic Bonding  All the electrons must be accounted for! CaP

16 Ionic Bonding CaP

17 Ionic Bonding Ca +2 P

18 Ionic Bonding Ca +2 P Ca

19 Ionic Bonding Ca +2 P -3 Ca

20 Ionic Bonding Ca +2 P -3 Ca P

21 Ionic Bonding Ca +2 P -3 Ca +2 P

22 Ionic Bonding Ca +2 P -3 Ca +2 P Ca

23 Ionic Bonding Ca +2 P -3 Ca +2 P Ca

24 Ionic Bonding Ca +2 P -3 Ca +2 P -3 Ca +2

25 Ca +2 P -3 Ca +2 P AAll the electrons must be accounted for! Ionic Bonding Ca -3

26 Ionic Bonding Ca 3 P 2 Formula Unit Ca 2+ P 3- Ca 2+ P 3- Ca 2+ P 3- Ca 2+

27 Properties of Ionic Compounds  Crystalline structure.  A regular repeating arrangement of ions in the solid.  Ions are strongly bonded.  Structure is rigid.  High melting points- because of strong forces between ions.

28 Crystalline structure

29 Do they Conduct?  Conducting electricity is allowing charges to move.  In a solid, the ions are locked in place.  Ionic solids are insulators.  When melted, the ions can move around.  Melted ionic compounds conduct.  First get them to 800ºC.  Dissolved in water they conduct.

30 Metallic Bonds  How atoms are held together in the solid.  Metals hold onto there valence electrons very weakly.  Think of them as positive ions floating in a “sea of electrons”.

31 Sea of Electrons  Electrons are free to move through the solid.  Metals conduct electricity.

32 Metals are Malleable HHammered into shape (bend). DDuctile - drawn into wires. EElectrons allow atoms to slide by

33 Ionic solids are brittle Force Strong repulsion breaks crystal apart.


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