Chemistry AS Everything about bonding and electronegativity

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  • Created on: 16-05-10 13:09
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Properties What happens as we go down a group? What happens as we go across a
Ionisation Energy Decrease Increase
More electrons are added to the Number of protons increases.
atoms. Stronger positive charge in the
More shells created. nucleus.
The outer electrons are shielded More attraction between nucleus and
from the nucleus. electrons.
Less attraction and it is easier to More energy needed to remove the
remove them
o Between Mg and Al, the IE
o The outer electron in Al is found in
the 3p orbital.
o Slightly higher energy than 3s orbital
(like Mg).
o Less energy is needed to remove the
Between P and S, there is a drop.
In the 3p orbital of P, there is only
one electron in each.
In the 3p orbital of S, one of the
orbital has 2 electrons.
Two paired electrons repel more. It is
easier to remove.
Atomic Radius Increase Decrease
Because of the increasing number One more proton is added in the
of electrons. nucleus and one more electron is
More shells are filled. added in the outer shell.
One extra main level. The charge in the nucleus
increases and there is more
attraction between the electrons
and the nucleus.
Electronegativity Decreases Increase
Atoms on the top Atoms get bigger. More protons are added
right of the periodic More main levels are added. Nuclear charge increases.
table are most More shielding between the outer Atomic radius decreases.
electronegative. electrons and the nucleus There is more attraction between
Less attraction. the outer shell electrons and the
increase Therefore less electronegative. nucleus.
Therefore they are more
Reactivity of Increases Increases
Atoms The period number increases and there As we go down the group, the atomic
are more electrons. More shielding and radius increases. The outer shell electrons
less attraction between the electrons and are further away from the nucleus. There
is more shielding and less attraction

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Electrons come off more between the nucleus and the electrons.
easily and atoms react faster. They come off more easily.
Ionic Bonding
Ionic bonding is the result of an electrostatic attraction between two oppositely charged ions.
Between one metal and one nonmetal.
Metals lose electrons and nonmetals gain it.
Metals may lose 1, 2 or 3 electrons at a time, it depends on their groups in the periodic table.
When metal atoms lose electrons, they become positive ions ­ cations.…read more

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Malleable and ductile because when a blow is given, positive ions are still surrounded by electrons
and the bonds are not broken.
High melting and boiling points because there is a strong attraction between the electrons and
positive ions and this extends through the whole lattice.
Covalent bonding
A covalent bond is a shared pair of electrons between two nonmetals.
Between 2 nonmetals.
Both need to fill their outer shell and become stable.
They share electrons and fill outer shells and create a molecule.…read more

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Electronegativity is the power of an atom to attract electron density towards itself in a covalent bond.
Electronegativity increases up the group because atoms get smaller, less main levels, less shielding
between the outer electrons and nucleus, and more attractions. The shared electrons are pulled to the
Electronegativity increases across the period because nuclear charge increases but number of main levels
stays the same. There is more attraction.
Electron density is the way the negative charge is distributed in a molecule.…read more

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This happens in water where the oxygen is more electronegative than hydrogen and it has a lone pair
of electrons.
They are dipole dipole forces but they are much stronger because of the lone pair and the
hydrogen atoms are small and very electron deficient. The protons are exposed.
The lone pair of electrons on the electronegative oxygen on one of the water molecule is strongly
attracted to the electron deficient hydrogen of another water molecule.…read more

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Summary table for the three
van der Waals forces Dipoledipole force Hydrogen bond
Between all molecules and Between the molecules with Between an electron deficient hydrogen
atoms polar bond and the lone pairs on an electronegative
Temporary because Permanent because electron It can be broken and reformed because
electrons move around cloud is found around most the hydrogen bonds are weak compared
causing the negative charge
electronegative atom in the to covalent bonds.
to shift molecule and the negative side
is permanently there.…read more


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