Bonding Flashcards
What is electronegativity like in ionic structures
Large differences in electronegativity
metals have low electronegativity
nonmetals have high electronegativity
What is electronegativity like in covalent structures?
Small differences in electronegativity
What is a covalent structure also referred to as
crystal structure
Ionic: general info
bond is between nonmetal and metal
electrostatic attraction between oppositely charged ions
NaCl
Structure: alternating positive and negative charges forming a giant ionic lattice
properties: high melting point, electrical conductors
when molten/solution
quite brittle
Covalent: General info
Bond is between non metals
The bond is shared pair of electrons - a single covalent bond
Macromolecular- diamond, Silicon, graphite
Molecular: I2 Iodine
Structure: diamond- bonded to 4 other carbons, just strong covalent bonds intermolecular forces
graphite- carbon bonded to 3 others within the layer and in between layers there are weak intermolecular forces ( van der waals) but strong covalent bonds in layers
iodine- strong covalent bond in molecule, but between molecules weak van der waals
Metallic
between metals
attraction between positive ions and negative delocalised electrons from outer shell of metals
example: magnesium
structure: metal ions in regular lattice with a sea of delocalised electrons- which come from the ions that have lost the electrons
Why do ionic structures have high melting points?
strong electrostatic attraction between oppositely charged ions, lots of energy to break. Increased charges on ions like the case of MgO ( Mg2+ and O2-) will lead to much stronger electrostatic attraction and a higher melting point
Why do ionic structures only conduct electricity when molten/solution
When solid these ions are held rigidly
into the ionic lattice and cannot move so when it is melted the ions are free to move and so can carry the charge
What are the properties of graphite
Slippery ( used as dry lubricant within engines where temperatures get high due to high melting point), due to carbons existing as layers with weak van der waal forces meaning layers can slide making it slippery.
Also it conducts electricity as it only bonds to 3 carbons, that means there is a lone electron that becomes delocalised so it moves throughout the structure and carries charge
What are the properties of molecular structures.
Low boiling point due to weak van der waal forces between molecules, meaning little energy required to break
Properties of metals?
High melting point because of strong attraction between positive ions and delocalised electrons , the increased charges of metal ions like Al3+ will mean there is a stronger attraction between the positive metal ions and electrons meaning a higher boiling point as more energy is required to break it
electric conductor -delocalised electrons move throughout structure
malleable/ductile- layers of ions can slide meaning we can easily shape it and stretch it into thin wires. retains strength as metallic bonding isn’t affected
What is dative covalent bonding?
donate a pair of a
Why is the bonding in Nitrogen Oxide (NO) covalent rather than ionic?
because the difference in electronegativity between nitrogen and oxygen is low enough to results in sharing of electrons which leads to the formation of a covalent bond.
Why is the melting point of Aluminium higher than sodium
greater charge and more delocalised electrons than sodium therefore stronger attraction between positive ions and negative electrons meaning it requires more energy to break and needs. a higher melting point
