topic 6 chemical bonding

• Why are noble gases monoatomic

  Noble gases (with the exception of helium) have eight valence electrons.

  They have full or complete outer shells

  Noble gases have stable electronic arrangements. They do not have to lose, gain or share electrons.

  As such, they do not combine with other atoms, but remain as unreactive elements. They exist as monoatomic elements
• Why do other atoms want to bond together

  All atoms sim to e like the noble gases ( Group 18) where they all have a stable electronic configuration.

  Only valence electrons are involved in bonding. Valency is the number of electrons an atom uses to form bonds.
• What are the three ways how atoms are bonded

  Ionic bonding (Transfer of electrons)

  covalent bonding (sharing of electrons)

  Metallic bonding ( only found in metals)
• What is the structure for ionic bonding

  Giant crystal lattice structure
• What is the structure for covalent bonding

  simple molecular structure

  Giant covalent structure
• What is the structure for metallic bonding

  metallic structure
• Formation of ions

  Atoms lose or gain electrons in order to achieve stable octlet or duplet configuration.

  When atoms lose or gain electrons, ions are formed

  Metallic atoms lose their valence electron to achieve the stable octet or duplet configuration

  They form positive ions (cations)
• What is ionic bonding

  Ionic bonds are form between metals and non-mental

  A transfer of electrons from a metal atom to a non-metal enables both to achieve the stable octet or duplet configuration.

  he resulting oppositely charged ions formed then attracted each other via strong electrostatic forces of attration. A giant crystal lattice structure is formed
• Properties of ionic compounds

  Ionic compounds have high melting and boiling points

  Ionic compounds cannot conduct electricity in the solid state.

  Most ionic compounds are hard but brittle

  Most ionic compounds are soluble in water but insoluble in organic compounds like oil

  Ionic compounds can conduct electricity when molten or dissolved in water
• What is the chemical formula for ammonium

  NH4
• What is the chemical formula for hydrogen

  H+
• What is the chemical formula for silver

  Ag+
• What is the chemical formula for copper(II)

  Cu2+
• What is the chemical formula for iron (II)

  Fe2+
• What is the chemical formula for lead

  Pb2+
• What is the chemical formula for Zinc 


  Zn2+
• What is the chemical formula for iron (III)

  Fe3+
• What is the chemical formula for hydroxide

  OH-
• What is the chemical formula for Nitrate

  NO3-
• What is the chemical formula for Carbonate

  CO32-
• What is the chemical formula for sulfate

  SO42-
• Why does ionic compounds have high boiling and melting points

  Large amount of energy is required to overcome the strong electrostatic forces of attraction between oppositely charged ions
• Why does ionic compound cannot produce electricity in solid state

  In solid state they are in fixed position. Thus they cannot move and cannot act as charge carriers to carry charges from one another
• Why can ionic compounds conduct electricity when molten or dissolved in water

  When in molten or aqueous state, the ions are mobile and moving ad act as charge carriers to carry charges from one another
• Why are most ionic compounds hard but brittle

  When a force is applied, ions with similar charge align and repel each other, causing shattering
• Why are most ionic compounds soluble in water but insoluble in organic compounds such as oil

  Water molecules are attracted to ion. This weakens the electrostatic forces between ions. As a result, the ions are pulled from the lattice structure and the compound dissolves.
• What is covalent bonding

  Covalent bonds are usually formed between atoms and non-metals by sharing electrons to form molecules.

  Sharing of electrons between the atoms allows them to achieve the octet or duplet configuration, forming a simple molecular structure.

  Each atoms contributes an equal number of electrons for sharing
• Structures of covalent substances exist in a wide range of structures

  Simple convalent molecules

  Giant covalent molecules ( diamond and graphite )

  Marcomolecules ( polymers)
• Structure and bonding of simple molecular substances

  structure: Most convalent substances exist as simple molecules

  Bonding: Within each molecule, the atoms are held by strong covalent bonds.

  Between the molecules there are weak intermolecular forces of attraction
• Properties of simple covalent molecules

  Simple covalent molecules have low melting and boiling points

  Convalent compounds cannot conduct electricity under all conditions

  Most covalent compounds are insoluble in water but soluble in organic solvents
• Why does simple covalent molecules have low melting and boiling points

  Little energy is required to overcome the weak intermolecular forces of attraction present between molecules

  Due to their low melting and boiling points, convalent molecules are gases or liquid at room temperature. They are volatile
• Why can't convalent compounds conduct electricity under all conditions

  There are no mobile ions or electrons to act as charge carriers to carry charges from one end to another
• What is giant covalent structure

  A structure with a giant molecular lattice structure made up of atoms held together in an extensive network by covalent bonds.

  Such solids are said to have giant covalent structure and are macromolecules
• Diamonds

  In diamonds, all carbon atoms are bonded together by strong covalent bonds throughout the solid ad are form in a tetranedral arrangement which makes it strong and rigid