Topic2 Structure and bonding

• Ionic bonding is formed by the transfer of electrons between atoms
• Metals lose electrons and become Cations - positive
• Non-metals gain electrons and become anions - negative
• Strong electrostatic attractionS between non-metal and metal
• Ionic compounds : will dissolve in water , Very high melting point to break the electrostatic attractions
• Covalent bond is when a pair of electrons are shared between atoms
• non-metals react to make covalent bonds
• Covalent molecules dont have high melting point because of weak intermolecular forces between molecules
• Molecular compounds don’t conduct electricity because there are no free electrons
• Most molecular substances are liquids/gases at room temperature
• Metals have very high melting points as it takes energy to overcome the strong metallic bonds
• Metal atoms have strong metallic bonds due to lots of positive ions held together by delocalised electrons
• Metallic bonding allows layers of lattice to slide
• metals are malleable
• positive metal ions are surrounded by a sea of negative delocalised electrons
• atoms in covalent molecules are held together by strong covalent bonds
• ionic compounds conduct electricity when dissolved or molten because the ions can move
• stick diagram shows bonds and the elements that are present
• 3D show shape of molecule and different sizing of elements
• Dot-cross diagram show electrons that are involved in bonding and single & double bonds