1.3 Bonding Flashcards
What is ionic bonding
Strong electrostatic forces of attraction between oppositely charged ions in a lattice
Properties of ionic compounds and why
High mtp - lots of energy needed to break strong electrostatic forces of attraction between oppositely charged ions
Conducts electricity - only when molten/in solution, ions are free to move and carry charge
What is simple molecular covalent bonding
Strong covalent bonds between atoms, weak van der waals forces of attraction between molecules
Properties of simple molecular covalent molecules
Can’t conduct electricity - all electrons used in bonding - not free to move
Low mtp - weak van der waals forces of attraction between molecules that don’t take much energy to overcome
Describe giant (macromolecular) covalent bonding
Giant lattice of many atoms held together by strong covalent bonds
Properties of giant covalent bonding
High mtp - lots of energy to overcome strong covalent bonds
Most dont conduct electricity - electrons used in bonding
Describe metallic bonding
Lattice of positive metal ions strongly attracted to a sea of delocalised electrons
Properties of metallic bonding
Malleable - layers can slide over each other
High mtp - strong forces of attraction between positive metal ions and negatively charged sea of electrons
Conduct electricity - delocalised electrons can move throughout the structure and carry charge
How does the strength of metallic bonds change across periodic table and why
Increases –> higher mtp and bp, stronger
Higher charge on metal ions
More delocalised electrons per ion
Stronger force of attraction between them
Define electronegativity
The ability of an atom to attract the pair of electrons in a covalent bond
What affects electronegativity
Nuclear charge
Atomic radius
Electron shielding
Most electronegative element
Fluorine - largest nuclear charge for its electron shielding, small atomic radius
How do you get a non polar bond
Both bonding elements have the same electronegativities
When do you get a polar bond
Bonding atoms have different electronegativities
Strongest imf
Hydrogen bonds
Describe van der waals forces of attraction
Temporary dipoles are created by the random movement of electrons –> induces dipole in neighbouring molecule –> temporary induced dipole-dipole attraction
Why are van der waals forces stronger in larger molecules
More electrons
Describe permanent dipole-dipole attraction
Some molecules with polar bonds have permanent dipoles –> forces of attraction between those dipoles and those of neighbouring molecules
What conditions are needed for hydrogen bonding to occur
H bonding to either O,N,F, lone pair of electrons on O, F, N
As O,N and F are highly electronegative, H nucleus is left exposed
Strong force of attraction between H nucleus and lone pair of electrons on O,N,F
Why is ice less dense than liquid water
In liquid water, hydrogen bonds constantly break and reform as molecules move about
in ice, the hydrogen bonds hold the molecules in fixed positions; this makes them slightly further apart than in liquid water
What is a dative covalent bond and when is it formed
Formed when an electron deficient atom/ion accepts a lone pair of electrons from an atom/ion with a lone pair of electrons
What does the shape of molecules depend on
Number of electrons in the valence shell of the central atom
Number of these electrons which are in bonded or lone pairs
What does the electron pair repulsion theory state
That electron pairs will take up positions as far away from each other as possible, to minimise the repulsive forces between them
Shape and angle of 2bp
Linear
180
