SASS Chem Bonding Summary

Page 1 ST ANDREW’S SECONDARY SCHOOL NAME CLASS CHEMISTRY Chemical Bonding in Substances : A Summary Bonding ⟺ Structure ⟺ Properties TEMPLATE ○1 State the structure. ○2 Describe the structure. ○3 Relate the structure to its property. Bonding COVALENT METALLIC IONIC Structure Simple molecular Giant covalent Giant metallic Giant ionic Composition Molecules Non-metallic atoms Metal atoms Ions: Anions & Cations Example CO2 / I2 Diamond / Graphite Fe / Cu NaCl / MgO Properties Melting and Boiling points / Volatility ① (substance) has a simple molecular structure. ② It consists of discrete molecules held together by weak intermolecular forces of attraction. ③ Very little energy is sufficient to overcome these forces. Hence it has low melting and boiling points. Diamond ① Diamond has a giant covalent structure. ② Each carbon atom is covalently bonded to 4 other carbon atoms in a tetrahedral arrangement, forming a continuous covalent network for its structure. ③ These strong covalent bonds require large amount of energy to overcome. Hence, it has high melting and boiling points. Graphite ① Graphite has a giant covalent structure. ② Each carbon atom is covalently bonded to 3 other carbon atoms in a giant covalent network. ③ These strong covalent bonds require large amount of energy to overcome. Hence, it has high melting and boiling points. ① (metal) has a giant metallic structure. ② It is held together by strong electrostatic forces of attraction between the positively charged cations and the ‘sea’ of delocalised electrons. ③ Large amount of energy is required to overcome these forces. Hence, it has high melting and boiling points. (exception: Hg) ① (substance) has a giant ionic structure. ② It is held together by strong electrostatic forces of attraction between the oppositely charged ions in a giant ionic lattice. ③ Large amount of energy is required to overcome these forces. Hence, it has high melting and boiling points. Melting point Boiling point HIGH LOW Strongbondingbetween particlesWeakinteractionsbetween particlesConductsElectricity? YES NO Contains mobilecharge carriersDoes not contain mobile charge carriers

Page 2 Electrical Conductivity ① (substance) has a simple covalent structure. ② It consists of discrete molecules that are electrically neutral. ③ Since it does not contain any mobile charged particles, it cannot conduct electricity. Diamond ① Diamond has a giant covalent structure. ② Each carbon atom uses all 4 of its valence electrons to form covalent bonds with 4 other carbon atoms. ③ Hence, it does not have any mobile electrons to conduct electricity. Graphite ① Graphite has a giant covalent structure. ② Each carbon atom uses only 3 out of 4 of its valence electrons to form covalent bonds with 3 other carbon atoms in a giant covalent network. ③ Hence, each carbon atom has 1 mobile valence electron that is delocalised between