C2

• Ionic bonding is the transfer of electrons between metal to non metal
• an ionic bond attraction is when oppositely charged ions are strongly attracted to one another by electrostatic forces
• ions are charged particles
• when metals form ions lose electrons to form positive ions
• when non metals form ions they gain electrons to form negative ions
• number of electrons lost or gained is same as charge on ion
• metals and non metals form ionic bonds
• ionic compounds carry electric charge when molten or dissolved in water due to free movement of ions
• ionic compounds have high melting points because the strong electrostatic attractions between oppositely charged ions require large amounts of energy to overcome
• covalent bonding occurs when two atoms share pairs of electrons
• group 1 elements form 1+ ions
• group 2 elements form 2+ ions
• group 6 elements form 2- ions
• group 7 elements form 1- ions
• group 1 and 2 are metals and lose electrons forming positive ions (cations)
• group 5, 6 and 7 are nonmetals and gain electrons to become negative ions (anions)
• Ionic compounds have structure called giant ionic lattice
• in ionic compounds - ions are a closely packed regular lattice arrangement which have very strong electrostatic forces of attraction between oppositely charged ions in all directions of lattice
• Ionic compounds all have similar properties
• ionic compounds can't conduct electricity when they're solid because the ions are held in place
• Covalent bonds share electrons
• Covalent bonds are between non metals
• Covalent bonds are very strong due to the positively charged nuclei of the bonded atoms that are attracted to the shared pair pf electrons by electrostatic forces
• Atoms only share electrons in outer shell
• To display covalent bonds either use dot and cross diagram or displayed formula or 3D model
• substances containing covalent bonds usually have simpler molecular structures
• In simpler molecular structures atoms within molecules are held together by very strong covalent bonds, forces of attraction between the molecules are very weak though
• To melt or boil the simple molecular compound you just have to break the weak intermolecular forces and not the covalent bonds
• Melting and boiling points of simple molecular substances are very low because the bonds are easily parted
• Most molecular substances are gas or liquid at room temperature
• Molecular compounds don't conduct electricity because they aren't charged and don't have free electrons
• Polymers are long chains of repeating units which together form a long molecule of repeating section
• Polymers are long chains of repeating units which together form a long molecule of repeating section
• Polymers are long chains of repeating units
• In polymers lots of small units are joined together to form a long molecule that has repeating sections joined by strong covalent bonds
• Most polymers are solids at room temperature because intermolecular forces between polymer molecules are stronger than simple covalent molecules so more energy is needed to break them
• The intermolecular forces in polymers are weaker than ionic or covalent bonds
• Polymers usually have lower boiling points than ionic or giant molecular compounds
• In giant covalent structures all atoms are bonded to eachother by strong covalent bonds
• Giant covalent structures have very high melting and boiling points as lots of energy is needed to break the bonds between atoms