Part 3- Chemical Bonds. Valence Bond Method, and Molecular Shapes Reference: Chapter 9-10 in textbook
1 PART 3 – Chemical Bonds, Valence Bond Method, and Molecular Shapes Reference: Chapter 9—10 in textbook
∨ alence electrons Valence electron Define: the outer shell electrons Important for determination of chemical properties Valence electrons AⅢAⅢ AA VA VIAⅦAWA Li·Be·B :N·:O::F::Ne In general the number of valence electrons of a representative element is equal to the group number
Valence Electrons Valence Electron Define: the outer shell electrons Important for determination of chemical properties 2
lonic Bond lonic bond Define: Attraction between cation (s )and anion(s) Cl Sodium atom Chlorine atom Sodium ion Chloride ion (a cation) (an anion) Sodium chloride(nacd Usually ionic bond is formed between an active metal atom and an active non-metal atom 3
Ionic Bond Ionic bond Define: Attraction between cation(s) and anion(s) Usually ionic bond is formed between an active metal atom and an active non-metal atom. 3
lonic Bonds Which compounds have ionic bonds? Cation: formed from active metal atoms, ( Group IA and lIA),e.g. Li, Na, Mg, K, Ca Anion: formed from active non-metal atoms, (Group VIA and VIIA), e.gO, F, S, Cl, Br, I How to represent ionic bonds? Cation and anions are written in brackets with the outmost shell of electrons and charges
Ionic Bonds Which compounds have ionic bonds? Cation: formed from active metal atoms, (Group IA and IIA), e.g. Li, Na, Mg, K, Ca, … Anion: formed from active non-metal atoms, (Group VIA and VIIA), e.g. O, F, S, Cl, Br, I, … How to represent ionic bonds? Cation and anions are written in brackets, with the outmost shell of electrons and charges. 4
Covalent bond Covalent bond formed between two(or more)non-metals, or one non-metal and one metal with low activity Atoms are connected by one pair(or more pairs)of shared electrons Examples H2, O2, N2, HCl, H2O, Co2, Co, C2 Br2 GaAs, ZnSe, Hgs
Covalent Bond Covalent bond: formed between two (or more) non-metals, or one non-metal and one metal with low activity. Atoms are connected by one pair (or more pairs) of shared electrons. Examples: H2, O2, N2, HCl, H2O, CO2, CO, C2Br2. GaAs, ZnSe, HgS 5