Bonding Flashcards
What is ionic bonding , give an example
Attraction between oppositely charged ions formed by the transfer of electrons from one atom to the other eg NaCl
What is covalent bonding , give an example
Pair of e- shared between two atoms eg H20
Definition of dative covalent bond and how you would represent one?
Pair of e- shared between two atoms one of which provides both electrons to the bond, arrow from atom with lone pair and atom with no electrons
What is metallic bonding
Attraction between cations and a sea of electrons
Why does a dative covalent bond occur
Covalent bonding happens because the electrons are more stable when attracted to two nuclei than when attracted to only one.
Why does metallic bonding occur
Metallic bonding happens because the electrons are attracted to more than one nucleus and hence more stable. The electrons are said to be delocalized – they are not attached to a atom=free
What happens to electronegativity across a period
Electronegativity increases across a period as the nuclear charge on the atoms increases but the shielding stays the same,
What happens to electronegativity down a group
Electronegativity decreases down a group as the number of shells increases, so shielding increases and the electrons are less strongly attracted to the atom.
Why are noble gases not electronegative
They do not form bonds
What charges are in Polar covalent bond?
Delta + and -
How are all bonds assumed covalent
Power of electro negativity from one atom in comparison too the other shows you which type- eg ionic one atom is more more electronegative hence is presented as gaining an electron
Solid structure..
Tightly packed , ordered infinitely repeating lattice
What kind of structure does ionic bonding make
lattice is an infinite and repeating arrangement of particles. All the anions are surrounded by cations and all the cations are surrounded by anions.
How can you increase melting and boiling point in ionic compounds
Higher charge
Smaller ions
Can ionic compounds conduct electricity
In solid =no act as good insulators
Liquid=yes ions can move
Why are ionic compounds strong
Ions cannot slip or move over each other
Metallic bonding forms a lattice but can conduct electricity, why?
Delocalised e- carry charge
How to increase mp and bp of metallic compounds
Smaller ions with higher charge
Why are metals soft,malleable and ductile
n-directional, it does not really matter how the cations are oriented relative to each other. The metal cations can be moved around and there will still be delocalized electrons available to hold the cations together. The metal cations can thus slip over each other fairly easily.
What is a sigma bond?
σ-bond is a bond resulting from direct overlap of two orbitals along the internuclear axis.
All single bonds between two atoms are σ-bonds.
Why can you only have one sigma bond between 2 atoms
another would force too many electrons into a small space and generate repulsion.
What is a pi bond?
If two orbitals overlap above and below (or behind and in front of) the internuclear axis, then a π-bond is formed.
+ or
A π-bond is a bond resulting from overlap of atomic orbitals above and below the internuclear axis.
All double bonds consist of a σ-bond and a π-bond.
Example of molecular substances
CH4,Cl2,NH3
What forces do molecular substances have
Intermolecular forces -usually weak
