Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chemistry Revision-C1 Part 3-Bonding and types of substances: (Metallic…
Chemistry Revision-C1 Part 3-Bonding and types of substances:
Ionic bonds
A reaction between a
metal and non-metal
where the
metal atom loses electrons to form a positive ion (cation) and the non-metal gains theses electrons to form a negative ion (negative ion).
These oppositely charged ions have a
strong electrostatic force
; This bond is called an ionic bond
An ion is an atom or group of atoms with a positive or negative charge
+means lose electrons, - means gains electrons
Compounds with 2 different types of atoms end in -ide
Compounds with 3 or more different types of atom with one of them being oxygen end in -ate
Potassium nitrate (K+ + NO3- = KNO3)
Ionic compounds (lattices)
Ions packed together in a
regular arrangement
, joined by ionic bonds are ionic compounds. (
metals and non-metals
)
Higher the ion charges, stronger the attraction, higher the melting and boiling points
Needs more energy to break bonds due to a
strong electrostatic attraction between oppositely-charged ions
so
high melting and boiling point
Brittle as they can slide over each other
Only
molten and solution state conducts electricity
because they aren't closely compact. Solid state can't conduct electricity as ions need to be free to conduct electricity (they can carry an electric charge)
Covalent Bonds
A strong electrostatic attraction between shared pair of electrons and the nucleus of that element
Involves sharing a pair of electrons between two non-metal atoms
Covalent bonding results in the formation of molecules
Properties of simple molecular compounds:
Strong covalent bonds but forces of attraction between molecules are weak. To melt and boil, you need to break intermolecular forces and not covalent bond;
low melting point
as molecules are easily parted from each other
Gas or liquid at room temperature
Bigger molecule, stronger intermolecular force so melting point increases
Don't conduct electricity because don't contain any free electrons
Some soluble, some not
Giant Covalent substances
Graphite and diamond are different forms of carbon and they are giant covalent substances
Graphite
Carbon atoms only forms three covalent bond each creating sheets of carbon atoms in hexagon form
No covalent bonds between layers; held weakly so free to move over each other: This makes graphite
soft and slippery
, so it's ideal as a lubricating material
High melting point
; lots of energy needed for covalent bonds to break
3 out of 4 outer electrons used in bonds so
each carbon atom has one electron that is delocalised (free) and can move; can conduct electricity and is often used to make electrodes
Diamond
Carbon atoms each form four covalent bonds
Strong covalent bonds take lots of energy to break; diamonds have a high melting point
Holds atoms in a rigid lattice structure making diamond really hard (used for cutting tools)
No free electrons;
doesn't conduct electricity
Fullerenes
Molecules of carbon, shaped like closed tubes or hollow balls
Mainly made of carbon atoms arranged in hexagons, pentagons or heptagons
Forms around another atom or molecule causing it to be trapped (used to deliver a drug directly to the cells in the body).
Buckminsterfullerence (C60)
A hollow sphere made up of 20 hexagons ans 12 pentagons.
Stable molecule that forms a soft brownish-black crystal
Graphene
Sheet of carbon atoms joined in hexagons. 1 atom thick so 2D compound
Simple polymers consist of large molecules containing chains of carbon atoms such as poly(ethene)
Metallic Bonding
Strong electrostatic attraction between positive metal ions and delocalized (free) electrons in a regular structure
Malleable
as layers of ions can slide over each other
Delocalised electrons flow through the structure towards the positive terminal; can
conduct electricity
Delocalised electrons carry electrical current and thermal energy through the material so are good conductors.
High melting point as it needs a lot of energy to break the bonds between the metal ions and the delocaslised electrons; shiny solids at room temperature
Aren't soluble in water
More dense than non-metals as closely packed together
Non-metals are dull-looking. more brittle, have lower melting points, don't conduct electricity and often have lower density