3.1.3 bonding Flashcards
What is ionic bonding?
The electrostatic attraction between oppositely charged ions in a lattice.
list the physical properties of ionic compounds.
high melting points, hard, brittle, conduct electricity when molten.
Why do ionic compounds have high melting points?
strong electrostatic forces of attraction between oppositely charged ions, that require lots of energy to overcome.
Why are ionic compounds hard?
distorted layers meaning they can’t slide over each other due to varied sizes of ions., lattice so strong forces of attraction.
Why are ionic compounds brittle?
mixed sizes of ions so its hard for them to slide over each other. some forces of repulsion.
Why do ionic compounds conduct electricity when molten?
charged ions are free to move when molten carrying charge.
What is a covalent bond?
occurs between two atoms of 2 non-metals and involves the sharing of electrons to obtain a noble gas structure.
What is dative covalent bonding?
An atom uses a lone pair of electrons to form a covalent bond.
What is a metallic bond?
the attraction between delocalised electrons and positive ions arranged in a lattice.
why are metals good conductors of heat?
tightly packed so heat energy can move faster over each ion.
Define electronegativity.
Power of an atom to draw electron density in a covalent bond towards itself.
How is electronegativity shared in a homonuclear diatomic molecule?
shared equally
How is electronegativity shared in a heteronuclear diatomic molecule?
focussed towards one atom causing a polar molecule.
Why is a heteronuclear diatomic molecule said to be polar?
the electron density lies towards thee more EN element, it’s shared unequally.
Why does EN increase across a period?
nuclear charge increases, shielding remains the same, atoms become smaller.
Why does EN decrease down a group?
atoms get bigger and shielding increases.
If EN of both atoms is less than 1.6-1.9 what bond is it?
metallic
If either atom has an EN greater than 1.9 and difference less than 0.5 what bond is it?
covalent
If either has an EN greater than 1.9 and the difference is more than 0.5 but less than 2.1 what bond is it?
polar covalent bond e.g oxygen and bromine
If the difference is greater than 2.1 what is the bond?
Ionic
What is an induced dipole?
electrons are constantly moving meaning at any given time it is possible for all electrons to be at one side. This causes a slightly more negative charge on one side inducing a dipole on a neighbouring molecule or atom. Causes weak forces of attraction.
What is a permanent dipole ?
The attraction between polar molecules.
What molecules involve hydrogen bonding?
Nitrogen, oxygen, Fluorine
