Chemical Bonding Flashcards
what is the Noble Gas Structure
2 (duplet configuration) / 8 (octet configuration) valence electrons: stable electronic configuration; lack of reactivity
what is the octet rule
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
what is an ion
atom or group of atoms that have electrical charges
what are cations and anions
cation: positively charged ion (lose electrons)
anion: negatively charged ion (gain electrons)
how are cations formed
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
how are anions formed
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
3 points
what is the relationship between group number and ionic charge
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
why do elements in groups 1-2, 13 form cations
they are metals
why do elements in group 18 not form ions
they tend to be monatomic as their atoms have stable electronic structure and do not usually form compounds
why do elements in groups 15-17 form anions
they are non-metals
*can also form covalent bonds
what is ionic bonding
ionic bond defined as the strong electrostatic forces of attraction between the positively charged ion (metals, cations) and negatively charged ion (non-metals, anions)
3 points
how are ionic compounds formed
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
what is covalent bonding
covalent bond defined as the electrostatic forces of attraction between the shared electrons and the 2 positively charged nuclei of the atoms
3 points
how are covalent bonds formed
generally occurs between atoms of non-metals
involves sharing of electrons to achieve noble gas electronic configuration
forms molecules
what is the structural full formula of H₂O
H - O - H
single bond
what is the full structural formula of O₂
O = O
double bond
what is the full structural formula of N₂
N ≡ N
triple bond
2 points
why do ionic compounds have high melting and boiling points
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
2 points each
why do ionic compounds not conduct electricity in the solid state but are good conductors in the molten and aqueous states
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
2 points
why do simple covalent/molecular substances have low melting and boiling points
they have a simple molecular structure
little energy is needed to overcome the weak intermolecular forces of attraction between the molecules
1 point
why do covalent substances generally not conduct electricity at any state
they have no mobile charge carriers (ions/electrons) to conduct electricity
