LES TENDANCES DANS LE TABLEAU PÉRIODIQUE ET LES COMPOSÉS MOLÉCULAIRES POLAIRES ET NON-POLAIRES

Rayon atomique

The distance from the center of the nucleus to the farthest layer (couche valence). The valence layer has less energy

Two trends - Rayon atomique

Trend 1:

• Going towards the right on the periodic table, the atomic radius decreases.

• The more protons in the nucleus, the more of a force of attraction between the electrons that go closer to the nucleus (?)

Trend 2:

• When going down the periodic table, the the the atomic radius increases

• There’s an electric layer that get bigger each period and the atom gets bigger.

ÉNERGIE D’IONISATION Trends

Trend 1:

• The more it goes right, the ionisation energy goes up.

• The electrons that are closer to the nucleus cost more energy to remove.

• The radius is much smaller so the electrons are closer to to the nucleus.

Trend 2:

• more down you go —> ionisation energy decreases

• the size of the atom increases with number electric layers and the electrons far from the nucleus and are easier to remove

AFFINITÉ POUR LES ÉLECTRONS

The quantity of energy that is freed when an electron is added to an atom to become a negative ion

Trends - AFFINITÉ POUR LES ÉLECTRONS

Trend 1:

• Go towards the right, the affinity for electrons goes up.

• Noble gases: affinity = 0

• When the radius (rayon) decreases, the element has a bigger affinity for electrons.

Trend 2:

• When going down, the affinity for electrons decreases.

• When the radius (rayon) is bigger, the element has a smaller affinity.

ÉLECTRONÉGATIVITÉ

A value given to an atom to show it’s capacity to pull and keep electrons. Based on the atome fluor

Molécules polaires

atoms that don’t share equally the electrons and an atom pulls more on an electron and causes dipole.

DIPÔLE

A small charged caused temporarily

Molécules non-polaires

Atoms that have the same electronegativity and does not cause dipoles