chap 3 chemical bonding & structure

• element 


  pure substance that cannot be broken down into 2 or more simpler substances by chemical method
• elements have a fixed melting and boiling point
• compounds


  pure substance containing 2 or more pure substances combined in a fixed ratio
• compounds have different properties from its constituent elements
• compounds have a fixed melting and boiling point
• compounds can be separated into its constituents by chemical methods
• mixture


  impure substance made up of 2 or more substances in a varying ratio
• mixtures usually have the same properties to it constituent substances
• mixture melt and boil over a range of temperatures
• mixture can be separated into its constituent substances by physical methods
• matter exists as elements, compounds or mixtures
• matter can have different types of bonding like ionic, covalent and metallic
• atoms lose electrons to form a cation
• atoms gain electrons to form anions
• ionic bonding is between a metal and non- metal to form an ionic compound
• metal atoms tend to lose electrons to form cations
• non-metals atoms tend to gain electrons to form anions
• type of FOA in ionic compounds

  strong electrostatic force of attraction
• what is the structure of ionic compounds ?

  they have oppositely charged ions that are held together in their fixed positions in a giant ionic lattice structure by strong electrostatic forces of attraction
• ionic compounds have a high melting and boiling point
• why do ionic compounds have a high melting and boiling point ?

  they have oppositely charged ions that are held together in their fixed positions in a giant ionic lattice structure by strong electrostatic forces of attraction, which require a large amount of energy to overcome
• ionic compounds have low volatility
• ionic compounds conduct electricity in their molten and aqueous state
• why do ionic compounds conduct electricity in their molten and aqueous state ?

  the giant ionic lattice structure breaks down, causing oppositely charged ions to separate and they are free to move within the liquid to carry the charge
• why do ionic compounds not conduct electricity in their solid state ?

  the oppositely charged ions are held in their fixed positions by strong electrostatic forces of attraction, no mobile ions to carry the charge
• ionic compounds are hard. true/ false

  true
• why are ionic compounds hard ?

  they have strong electrostatic forces of attraction between oppositely charged ion that requires a large force to break
• ionic compounds are brittle. true/ false?

  true
• why are ionic compounds brittle ?

  when enough force is applied, ions move away from their lattice position and ions of the same charge approach each other. these repulsive forces are larger than the attractive forces and causes the structure to break
• ionic compounds are not brittle. true/ false?

  false
• ionic compounds are soluble in water but not organic solvents
• the 2 ionic compounds not soluble in water are copper (II) carbonate and silver chloride
• covalent bonding is between non- metals
• type of FOA in covalent bonding

  strong intermolecular force of attraction
• types of covalent molecules:

  simple covalent molecules, macromolecules and giant covalent molecule
• simple covalent molecules have a low melting and boiling point
• why do simple covalent molecules have a low melting and boiling point ?

  they have a simple molecular structure with weak intermolecular forces of attraction. a small amount of energy is required to overcome these forces of attraction
• simple covalent molecules are volatile
• simple covalent molecules do not conduct electricity
• why do simple covalent molecules not conduct electricity ?

  they are electrically neutral simple molecules and do not have mobile ions to carry the charge