Electronegativity Flashcards
When are simple molecules formed?
When non- metal atoms share pairs of electrons to achieve a full outer energy level of electrons
What happens to the orbitals when a bond forms between 2 atoms?
Their orbitals overlap and the electron that was in each of their individual orbitals joins to the other electron and forms a bond
What type of bond is it when orbitals have overlapped end to end?
A sigma bond
How are the atoms held together?
Their nuclei are attracted to the shared electron density (the electrons aren’t in a fixed position)
What is the sigma bond equivalent to?
A single covalent bond
What is the sigma bond equivalent to?
A single covalent bond
When is a Pi bond formed?
When orbitals overlap side by side- how a double bond forms between molecules
What type of sigma bond do we get if atoms of the same element are sharing electrons?
A perfectly symmetrical
What type of sharing of electrons will it be if the atoms are different?
An unequal share of electrons
What is the definition of electronegativity?
The ability of an atom to attract shared electrons in a covalent bond
What factors affect electronegativity?
The nuclear charge
The distance between the nucleus and the shared pair of electros (the covalent radius)
What happens to electronegativity as you go across a period?
Electronegativity increases
Why does electronegativity increase as you go across a period?
The nuclear charge increases
Same shielding
What happens as you go up a group in the periodic table?
Electronegativity increases
Why does electronegativity increase up a group?
The distance between the nucleus and the shared pair of electrons is decreasing because each of the atoms has a smaller number of occupied energy levels
Where are the most electronegative elements found?
The top right of the periodic tale
Where are the least electro negative elements found in the periodic table?
The bottom left
When is there a charge imbalance in a bond?
When electron density is pulled closer to one atom than the other
What does delta plus mean?
Slightly positive
Electron deficient
What does delta negative mean?
Slightly negative
Electron rich
When is a polar bond formed?
When there is a charge imbalance
What is a dipole?
The combination of the delta plus and the delta minus
2 poles- there is a partial charge present
The larger the electronegativity difference means what in terms of dipoles?
The larger the dipole
A polar molecule must contain what?
A polar bond
Do polar molecules have stronger or weaker attractions between molecules?
Stronger (intermolecular forces)
Are polar molecules more or less likely to be water soluble?
More likely
Do polar molecules have higher or lower melting points than non-polar molecules?
Higher melting points
How can a molecule be non-polar but still have polar bonds?
The molecule is symmetrical so therefore the dipoles cancel out
