Bonding
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2 main types of bonding in compounds
Ionic Covalent
sulfate ion
SO4^2-
hydroxide ion
OH-
nitrate ion
NO3- (3 IS below)
carbonate ion
CO3 ^2-
ammonium ion
NH4^+
what struc does sodium chloride have
giant ionic lattice
Sodium azide has a high melting point. Predict the type of bonding in a crystal of sodium azide. Suggest why its melting point is high.
Ionic Oppositely charged ions / Na+ and N3 ions Strong attraction between (oppositely charged) ions / lots of energy needed to overcome (strong) attractions (between ions) - mark scheme ans
3 features of ionic compounds
1) conduct electrivcity when molten or dissolved - free moving ions that can carry charge 2) ionic compound have high melting points - strong electrostatic attraction bet oppositely charged ions that take alot of energy to overcome 3)ionic compounds tend to dissolve in water - water mol are polar charged parts pull ions away from lattice
what is covalent bonding
atoms have a shared pair of electrons
what struc has huge network of covalently bonded atoms
giant covalent stuc macromolecular struc
What is a dative covalent bond?
2 electrons are donated from one atom to another / a lone pair of electrons rather than one from each
2 types of covalent structures
Simple molecular I simple covalent Macro molecular/giant covalent structures
Examples of simple covalent
Co2 Ch4 Cl2
What is broken when boiling covalent structures
IMF’s not the strong covalent bonds
Examples of giant covalent struc
Diamond, graphite, silicon dioxide
Describe diamonds structure and its properties
Each carbon atoms makes 4 bonds sono free electrons to form used of delocalised electrons to carry charge or conduct electricity thus diamond cannot conduct. Diamond is hard with a high melting point due to strong covalent bands that take a lot of energy to break Diamond is insoluble in water
Describe graphite structure and its properties
Giant covalent structure Can conduct electricity as each carbon atom makes 3 bonds so there is one free delocalised electron per carbon atom forming sea of delocalised elections that can more throughout structure and conduct electricity. Graphite is soft BCD weak IMF’s I vow between layers d’atoms allowing them to slide over eachother Has high melting point due to strong covalent bands within mol
Where are covalent bands and imfs found
Covalent - within IMF’s found between
What is metallic banding ?
Lattice of positive ions surrounded by sea of delocalised_ electrons There are electrostatic attractions
Properties of metals
Good conductors due to sea of delocalised electrons High melting and boiling point do to strong bands due to strong attraction
Properties of metals going down a group
Usually looking @ groups 123 - all ions have same charge so this factor not important instead looking at increasing atomic radius so delocalised e-further away from metalions so weaker attraction = weaker metallic bond and so lower boiling point
Properties of metals across a period
Increase in melting point due to increasing charge so stronger attraction between the positive ions and e-so stronger metallic bonds so higher melting point
Why does boron trichlovide have tribunal planar shape?
3 bonds that repel equally to get as for away from eachother as possible lo minimise repulsion.