Drawing dot- and- cross diagrams, showing the electrons in the outermost shells.

You will need to use the periodic table to determine the Group of the elements.

I will go through this section using examples.

Part 1: Dot- and- cross diagram for atom


Question: Draw a dot- and- cross diagram for oxygen atom, showing the electrons in the outermost shells.



Oxygen is in Group VI --> 6 valence electrons.


oxygen atom, dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and - cross diagram of oxygen atom



Question: Draw a dot- and- cross diagram for calcium atom, showing the electrons in the outermost shells.

Calcium is in Group II --> 2 valence electrons.




calcium atom, dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of calcium atom



Part 2: Dot- and- cross diagram for Ionic Compounds

Recap - Ionic compounds are made of metals and non- metals.



Question: Draw a dot- and- cross diagram for calcium oxide, showing the electrons in the outermost shells.



Answer:
Calcium --> Group II --> 2 valence electrons --> charge is +2, so take away all the valence electrons --> go to the inner shell --> 8 electrons.

Oxygen --> Group VI --> 6 valence electrons --> charge -2, so add 2 electrons --> total 6+2 =8 valence electrons.

  
ionic compound,  dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of calcium oxide 


Question: Draw a dot- and- cross diagram for magnesium fluoride, showing the electrons in the outermost shells.


Answer:
Formula of magnesium fluoride is MgF2.


Magnesium--> Group II --> 2 valence electrons --> charge is +2, so take away all the valence electrons --> go to the inner shell --> 8 electrons.

Fluorine --> Group VII --> 7 valence electrons --> charge -1, so add 1 electrons --> total 7+1 =8 valence electrons.
ionic compound,  dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of magnesium fluoride



Part 3: Dot- and- cross diagrams for simple molecules (covalent molecules).

Recap - Covalent molecules are made up of two of more atoms of non- metals.


Question: Draw a dot- and- cross diagram for oxygen molecule, O2, showing the electrons in the outermost shells.



Answer:

oxygen molecule, covalent molecules,   dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of oxygen molecule




Question: Draw a dot- and- cross diagram for chlorine molecule, Cl2showing the electrons in the outermost shells.

Answer:

chlorine molecule, covalent molecules,   dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of chlorine




Question: Draw a dot- and- cross diagram for ammonia, NH3, showing the electrons in the outermost shells.



Answer:

ammonia molecule, covalent molecules, covalent compounds,  dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of ammonia





Question: Draw a dot- and- cross diagram for methane, CH4, showing the electrons in the outermost shells.

Answer:

methane molecule, covalent molecules, covalent compounds,   dot and cross diagram, showing outermost shells only, valence electrons only
Dot- and- cross diagram of methane

1 comment:

  1. This is a great article for my research. Keep posting. Thank you.

    Bob
    www.gofastek.com

    ReplyDelete