2.1- ionic model

when metal atoms lose electrons, positive ions

when non metal atoms gain electrons they form negative ions

electrostatic attraction between oppositely charged ions

exist as 3D lattice structures

NH4+

OH-

NO3-

HCO3-

CO3 2-

SO4 2-

PO4 3-

compunds with two elements named with cation first followed by anion anion adopts the suffix “ide” eg magnesium sulfide or sodium oxide

measure of the strength of the ionic bond in different compounds

to achieve a decrease in their potential energy, lower energetic state is more stable, in practice this is achieved by atoms gaining a full outer shell 3 major types of electronic interaction are possible, resulting in 3 different bonding, what type occurs depends on electronegativity difference of atoms interacting

low electronegativity atoms (metals) interacting with high electronegativity atoms (non-metals) electronegativity difference bigger than 1.7 units

both atoms have middle to high electronegativity (both non-metals) electornegativity difference less than 1.7 units

both atoms have low electronegativity (both metals)

giant ionic -solid insulator -melt/ dissolve conduct -brittle -high melting point -hard some are soluble

simple covalent giant covalent macromolecules simple covalent: weak intermolecular forces, low melting points, weak, brittle, non- conducters giant covalent: high melting point, non conducter (except graphite), insoluble

metal loses electrons to form a positive ion (cation), oxidation non metal will gain electrons to form a negative ion (anion), reduction in both cases atoms achieve the same electronic configuration as nobel gases. This is called ISOELECTRONIC

M -> Mn+ + ne- n= a number

X + ne- -> Xn-

electrostatic force of attraction between oppositely charged ions causes them to pack together into a 3d Giant ionic lattice with every cation surrounded by anions and vis versa the electrostatic attraction, between ions is the ionic bond

as cation has been formed through loss of outermost energy level the cations are smaller than metal atoms as anion has formed by the gain of electrons they are bigger than the neutral atom, due to increase in electron electron repulsion and expansion of the outer energy level, in general the cation is smaller than the anion