chemical bonding
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where are noble gases in the periodic table?
group 0
how reactive are noble gases?
unreactive and stable
why are noble gases stable?
valence electron shells are fully-filled with electrons and exist as monoatomic elements
how can atoms achieve a stable noble gas electronic configuration?
losing electrons, gaining electrons, sharing electrons
what is an ion?
a charged particle formed when an atom loses or gains electrons
what type of ions do metals form?
cations (positive ions)
what type of ions do non-metals form?
anions (negative ions)
what is a giant ionic crystal lattice?
many ionic bonds between the oppositely-charged ions
what features does a giant ionic crystal lattice have?
ions held togfether by strong ionic bonds + packed in a regular pattern
what is a strong ionic bond?
strong electrostatic forces of attraction between oppositely charged ions
why do ionic compounds have high mp/bp?
ions in ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions which requires a large amount of energy
why are ionic compounds usually soluble in water?
water molecules can separate the positive ions from the negative ions which causes the ionic compound to dissolve in water
why are ionic compounds usually insoluble in organic solvents?
the ions remain in a giant lattice structure in organic solvents
why are ionic compounds usually conduct electricity in molten state or when dissolved in water?
in the molten/aqueous state, ions can move freely and can behave as mobile charged carriers to conduct electricity
why are ionic compounds do not conduct electricity in solid state?
in the solid state, ions are held in fixed positions in the giant lattice structure and are not free to move
when is a covalent bond formed?
when two atoms share valence electrons
what kind of elements can form covalent bond?
non-metals of the same elements and atoms of different elements
what is the relationship between bonds and the pair of electrons shared?
x pair = x bond
how do most covalent substances exist?
simple discrete molecules have simple molecular substances
why do covalent molecules with simple molecular structure have low mps/bp?
discrete molecules/covalent bonds held by weak intermolecular forces of attraction between the molecules which require little energy to overcome
why are covalent molecules with simple molecular structures usually soluble in water?
water molecules cannot separate the structure of simple molecular substances
what are covalent molecules with simple molecular structures soluble in?
soluble in organic solvent?
why do covalent molecules with simple molecular structure not conduct electricity in any states?
simple molecular substances are neutral discrete molecules and thus do not have any mobile ions or delocalised electrons to acts a mobile charged carriers to conduct electricity
what is an allotrope?
different forms of the same element