IGCSE Simple molecules & Covalent bonds

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IGCSE Chemistry Notes Simple molecules  & Covalent bonds 

Topic:Atoms, elements and compounds

Sub Topic: 2-5-simple-molecules-and-covalent-bonds

Syllabus Objectives

Core :

  •  State that a covalent bond is formed when a pair of electrons is shared between two atoms leading to noble gas electronic configurations
  •  Describe the formation of covalent bonds in simple molecules, including H2, Cl 2, H2O, CH4, NH3 and HCl.
  • Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules
  • Describe in terms of structure and bonding the properties of simple molecular compounds: 

           a) low melting points and boiling points

           b) poor electrical conductivity

EXTENDED/SUPPLEMENT

  • Describe the formation of covalent bonds in simple molecules, including CH3OH, C2H4, O2, CO2 and N2.
  • Use dot-and-cross diagrams to show the electronic configurations in these and similar molecules
  •  Explain in terms of structure and bonding the properties of simple molecular compounds:
  • (a) low melting points and boiling points in terms of weak intermolecular forces (specific types of intermolecular forces are not required)
  • (b) poor electrical conductivity

Video Lectures

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Topic: Simple Molecules and Covalent Bonds / Test your Understanding

Click the highlighted blanks to reveal the correct answer.

1. A covalent bond is formed when a pair of
________________ electrons
is shared between two
________________ atoms
.
2. Covalent bonding helps atoms achieve
________________ noble gas
electronic configurations.
4. Dot-and-cross diagrams are used to show
________________ electronic configurations
in molecules.
5. In simple molecular compounds, melting points and boiling points are usually
________________ low
.
6. Simple molecular compounds have poor electrical
________________ conductivity
.
 
8. The low melting and boiling points of simple molecular compounds are due to weak
________________ intermolecular forces
.
9. Specific types of intermolecular forces are
________________ not required
at this level.
10. In H2, two hydrogen atoms share
________________ one pair of electrons
.
11. In Cl2, each chlorine atom shares
________________ one electron
to form a single covalent bond.
12. In water, oxygen forms
________________ two
covalent bonds with hydrogen atoms.
13. In methane, carbon forms
________________ four
covalent bonds.
14. In ammonia, nitrogen forms
________________ three
covalent bonds with hydrogen atoms.
15. In hydrogen chloride, hydrogen and chlorine share
________________ one pair of electrons
.
16. Simple molecular compounds conduct electricity poorly because they do not contain
________________ free ions or electrons
.
17. Covalent bonds are usually formed between
________________ non-metal
atoms.
18. O2 contains a
________________ double bond
between the two oxygen atoms.
19. N2 contains a
________________ triple bond
between the two nitrogen atoms.
20. CO2 contains
________________ two double bonds
between carbon and oxygen atoms.
21. C2H4 contains a
________________ double bond
between the two carbon atoms.
22. CH3OH is the formula for
________________ methanol
.
23. The properties of simple molecular compounds can be explained by their
________________ structure and bonding
.

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