Electronegativity and molecules

What is electronegativity

The relative attraction an atom in a molecule has for the shared pair of electrons in a covalent bond

Where are electrons in a covalent bond

In the region between the nuclei

What happens if both atoms are of equal charge

The electrons will fluctuate between the atoms

What happens to the atom of a stronger charge in an uneven bond

The nucleus will have a stronger pull on the electrons, causing a shift in electron density towards that atom, making that atom partially negative.

What happens to the atom of a weaker charge in an uneven bond

Electrons shift away from the atom, giving it a partially positive charge

Which elements on the periodic table have a higher electronegativity

Upper right

Why do elements on the right have a higher electronegativity

More protons in their nucleus

Why do upper electrons have a higher electronegativity

Less shells blocking the positive charged nucleus

0-0.4 =

Non-polar covalent bond

0.4-1.7 =

Polar covalent bond

1.7 +

Ionic bond

What is an inter molecular force

Forces in between molecules

Where are van der waal forces found

Between non polar covalent molecules or symmetrical molecules

How do Van Der Waal forces form

Electrons are fluctuating back and forth between the two atoms.

At any one moment the electrons are at one atom, causing a temporary partial charge.

When this temporarily partial charge comes in contact with another molecule, it forms a temporary dipole.

What happens when the number of electrons is increased for an atom under van Der waal force

Force strength increases, due to partial charge being stronger

What happens when number of van Der waal forces is increased

Overall properties of material become stronger

What is a permanent dipole?

Permanent partial charge

What is a dipole-dipole force

Interaction between oppositely charged permanent dipoles

What is hydrogen bonding

A strong dipole dipole force between a electron deficient hydrogen in one molecule and a lone pair in another, highly electronegative molecule.

Where can hydrogen bonding occur

Between hydrogens and fluorine/nitrogen/oxygen

What does VSEPR stand for

Valence Shell Electron Pair Repulsion Theory

What does VSEPR state

Pairs of electrons repel each other

Lone pairs repel more than shared bonding pairs

Why do lone pairs repel more

They take up more space.

Bonding pairs occupy the electron cloud in between nuclei.

How do you decide the shape of a molecule

Count the number of lone pairs (LP) and bonding pairs (BP)

1 or 2 BP =

Linear 180°

3 BP=

Trigonal planar 120°

4 BP =

Tetrahedral 109.5°

3 BP=

Trigonal planar 120°

6 BP

Octahedral

3BP 1LP

Pyramidal 107°

2BP 2LP

V shaped 104.5°