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WATER
IONIC BONDING

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Atoms are involved in a reaction where one atom gains electrons and
becomes an anion, the other loses electrons and becomes a cation



Ionic bonding holds them together

Anion: negative ion
Cation: positive ion

COVELANT BONDING
 Atoms share electrons
 When the electron is not shared evenly, part of the molecule becomes
slightly positive(δ+) and the other part becomes slightly negative(δ-)

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These are called polar molecules
They have unequal charge distribution
Common in hydrogen bonds
Dipole: separation of charge

H20
 Water is polar because electrons are held closer to oxygen
 Hydrogen bond: the (δ-) oxygen will attract the (δ+) hydrogen from
another molecule, forming a weak electrostatic bond
 Although hydrogen bonds are weak, there are so many of them to
break, making melting and boiling points high

Properties of H20
 Polar: many covalently and ionically bonded substances can dissolve
in it
 Transport medium: since its dipole, many substances can dissolve in it
 Low density: the maximum density of water is at 4 degrees Celsius ,
below that temperature the molecule in ice are widely spread out,
making it less dense and therefore floats on water, creating a barrier
because ice is less dense than water
...
This creates a stretchy surface on water that some insects
can walk on



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