The chemical context of life

Key concepts –Matter consists of chemical elements in pure form and in combinations called compounds –An element’s properties depend on the structure of its atoms –The formation and function of molecules depend on chemical bonding between atoms –Chemical reactions make and break chemical bonds

Key concepts –Matter consists of chemical elements in pure form and in combinations called compounds –An element’s properties depend on the structure of its atoms –The formation and function of molecules depend on chemical bonding between atoms –Chemical reactions make and break chemical bonds

The formation and function of molecules depend on chemical bonding between atoms Different types of bonds Covalent bonds (strongest) - involves the sharing of electrons (i.e. H 2 ) Electrons may be spread equally across the bond (non-polar bond) Electrons may not be spread equally across the bond (polar bond)

The formation and function of molecules depend on chemical bonding between atoms Different types of bonds Covalent bonds (strongest) - involves the sharing of electrons (i.e. H 2 ) Electrons may be spread equally across the bond (non- polar bond) Electrons may not be spread equally across the bond (polar bond) Ionic bonds- Charge-charge interactions An interaction between a positive and negative charge Can form after one atoms strips a valence electron from another (ie. NaCl) forming a salt

The formation and function of molecules depend on chemical bonding between atoms Ionic bond Electron transfer forms ions Na Sodium atom Cl Chlorine atom Na + Sodium ion (a cation) Cl – Chloride ion (an anion)

Which elements will most likely form an ionic bond? a. Li and F b. C and O c. N and O d. Si and Cl e. H and H

The formation and function of molecules depend on chemical bonding between atoms Different types of bonds (weak) Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom

The formation and function of molecules depend on chemical bonding between atoms Different types of bonds (weak) Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom This impacts the properties of water!

The formation and function of molecules depend on chemical bonding between atoms Different types of bonds (weak) Hydrogen bonds- involve polar covalent bonds, form when a hydrogen atom is bonded to a more electronegative atom Vander Waals interactions- involve non-polar covalent bonds, occur when an electron accumulation arises by chance

The formation and function of molecules depend on chemical bonding between atoms

Chemical reactions make and break chemical bonds

Chemical reaction- making a breaking of chemical bonds leading to changes in the composition of matter

Chemical reactions make and break chemical bonds Chemical reaction- making a breaking of chemical bonds leading to changes in the composition of matter 6 CO H 2 O C 6 H 12 O 6 + 6O 2

Chemical reactions make and break chemical bonds

Key concepts –Matter consists of chemical elements in pure form and in combinations called compounds –An element’s properties depend on the structure of its atoms –The formation and function of molecules depend on chemical bonding between atoms –Chemical reactions make and break chemical bonds