(Wk3) Covalent Bonds, Ions and Ionic Bonds Flashcards
What is Electronegativity?
Tendency of an atom to attract a shared pair of electrons towards itself.
How does Electronegativity change throughout the Periodic Table?
-Increases across period.
-Decreases down a group.
What is the most and least electronegative element?
-Most: Fluorine
-Least: Caesium
Why does electronegativity increase across a period?
Because nuclear charge of atom increases and atomic radius decreases.
Why does electronegativity decrease down a group?
Because atomic radius increases, with a greater number of energy levels (screening effect).
What is ionisation energy?
Energy required to remove an electron from a gaseous ion/atom.
What is an Ionic Bond?
Electrostatic attraction bond, between oppositely charged ions.
It is formed by the transfer of electrons between atoms.
What is a Covalent Bond?
Bond formed by the sharing of electrons between atoms (non-metals).
Give 2 characteristics of Ionic Bonds
Good conductors of electricity and have high melting points.
(Strongest of all chemical bonds- require high energy input to be broken)
What does it mean when a molecule is POLAR?
It means it has a negative dipole and a positive dipole.
(*dipole=ion)
Give some characteristics of Covalent Bonds.
-Stable non conductors
-Non polar (between atoms of similar electronegativity)
-Do not have charged dipoles > dipole moment is zero
-Polar (between atoms of dissimilar electronegativity)
Explain the polarity of water molecules.
-Water molecules can exist with 2 single polar covalent bonds.
-OR, electrons can polarise further, breaking one covalent bond and producing 2 dissociated charged ions H+ and OH-
Explain the concept of ionisation of water.
-Dissociated H+ ion can bind directly with another H2O molecule to form a Hydronium Ion H3O+
-Water ionisation occurs constantly and reversibly; water is a mixture of H2O, OH- and H3O+
What is the definition of bond length?
Average distance between the nuclei of two covalently bonded atoms.
What is the definition of atomic radius?
Half the distance between the nuclei of two identical atoms, joined by a single covalent bond.
