Chemical Bonding

2 (duplet configuration) / 8 (octet configuration) valence electrons: stable electronic configuration; lack of reactivity

tendency for atoms to lose/gain/share electrons until there are 8 valence electrons *exception to this rule applies to atoms with only 1 electron shell, requiring only 2 valence electrons for stability

atom or group of atoms that have electrical charges

cation: positively charged ion (lose electrons) anion: negatively charged ion (gain electrons)

atoms of metals tend to form cations by losing their valence electron(s) to attain the noble gas configuration positive charge arises as there are now more protons than electrons *most metals have 1-3, easier to lose 1-3 than to gain 5-7

atoms of non-metals tend to form anions by gaining valence electron(s) to attain the noble gas configuration positive charge arises as there are now more electrons than protons *most metals have 4-7, easier to gain 1-3 than to gain 5-7

ionic charge of an ion is dependent on number of valence electrons its atom contains elements in the same group have the same number of valence electrons hence, they form ions of the same charges and have similar chemical properties

they are metals

they tend to be monatomic as their atoms have stable electronic structure and do not usually form compounds

they are non-metals *can also form covalent bonds

ionic bond defined as the strong electrostatic forces of attraction between the positively charged ion (metals, cations) and negatively charged ion (non-metals, anions)

generally occurs between atoms of metals and atoms of non-metals involves gain/loss of electrons (transfer of electrons) to achieve stability forms oppositely charged ions *include legend for dot-and-cross diagrams

covalent bond defined as the electrostatic forces of attraction between the shared electrons and the 2 positively charged nuclei of the atoms

generally occurs between atoms of non-metals involves sharing of electrons to achieve noble gas electronic configuration forms molecules

H - O - H single bond

O = O double bond

N ≡ N triple bond

they have a giant ionic crystal lattice structure a lot of energy is needed to overcome the strong electrostatic forces of attraction between the oppositely charged ions

in the solid state, the ions are held in their fixed positions by strong electrostatic forces of attraction the ions are not mobile to conduct electricity in the molten/aqueous state, the electrostatic forces of attraction are overcome the ions are mobile to conduct electricity

they have a simple molecular structure little energy is needed to overcome the weak intermolecular forces of attraction between the molecules

they have no mobile charge carriers (ions/electrons) to conduct electricity