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Ionic bonding
An ionic bond is an attraction between oppositely charged ions, which are formed by the
transfer of electrons from one atom to another.

This electrostatic attraction holds the ions together and is very strong.

Covalent bonding

A covalent bond is a pair of electrons…

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Dative covalent bond

A dative covalent bond is a pair of electrons shared between two atoms, one of which provides
both electrons to the bond.

Covalent bonding happens because the electrons are more stable when attracted to two nuclei than
when attracted to only one. Covalent bonds should not be…

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Electronegativity has no units and is measured on a scale from 0.7 to 4.0. This is called the Pauling

H He


Li Be B C N O F Ne

1.0 1.5 2.0 2.5 3.0 3.5 4.0

Na Mg Al Si P S Cl Ar

0.9 1.2 1.5 1.8…

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for them to move particles themselves.
from one cluster to Therefore the
another. Therefore particles move freely.
the particles can move
freely and randomly.
Spacing of Particles In a solid, the particles are Packed together but In a gas, all the
tightly packed together in with spaces in particles are…

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Good conductors in liquid state- this is because the delocalised
electrons can carry a current.
Strong, malleable, ductile- this is because there are no bonds holding
specific ions together so the metal ions can slide over each other.
Insoluble because of the strength of the metallic bond.


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present between all molecules, although they can be very weak. They are the reason all compounds
can be liquefied and solidified.

The strength of the Van der Waal's forces in between molecules depends on two factors:

The number of electrons in the molecule- the greater the number of electrons in…

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Periodicity is the regular recurrence of the properties of elements when they are arranged in
atomic number order as in the periodic table.

Atomic Radius

Going across Period 3:

The number of protons in the nucleus increases so the nuclear charge increases because there are
more electrons, but the increase…

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their attraction to the nucleus, so less energy is needed to remove one of these paired electrons
than is needed to remove an unpaired electron from phosphorus.


Going across Period 3:

The nuclear charge increases and the atomic radius decreases because there are more electrons,
but the increase in…

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Explaining the trend of melting and boiling points from Na to Al

Sodium, magnesium and aluminum

Sodium, magnesium and aluminum are all metals. They have metallic bonding, in which positive
metal ions are attracted to delocalized electrons.

Going from sodium to aluminum:

The charge on the metal ions increases from…

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Silicon is called a semiconductor because:

The four outer electrons in each atom are held strongly in covalent bonds and few electrons have
enough energy at room temperature to enter the higher energy levels so there are few delocalized
electrons and silicon is a poor conductor but at higher temperatures…


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