chemistry 2 Flashcards
What is ionic bonding
Ionic bonding is the electrostatic attraction between positive ions and negative ions. It is relatively strong attraction
How are ionic compounds held together
a giant structure of ions, held together by strong electrostatic forces of attraction between oppositely charged ions.Held in a giant lattice.
State properties of ionic substances
High melting/boiling point
Don’t conduct electricity when solid
Conduct when molten or dissolved in water-ions are free to move
giant covalent structures
consist of many atoms covalently bonded in a lattice structure
What is important when working out a formula of an ionic compound
Ionic compounds are electrically neutral i.e, positive and negative charges cancel each other out
How are ionic compounds formed.Explain in terms of MgO
Reaction of a metal with a non-metal.Electron transfer occurs-metal gives away outer shell electrons to non-metal.
What is a covalent bond
A covalent bond is when two nonmetals share a pair of electrons.
Describe the structure and properties of simple molecular covalent substances
Don’t conduct electricity(no ions)
Small molecules
weak intermolecular forces
Low melting/boiling point
How do intermolecular forces change as size of molecules increase
They increase.That causes melting/boiling points to increase as well(more energy needed to overcome these forces
What are polymers
Polymers are very large molecules with atoms linked by covalent bonds
What are thermosoftening polymers
Special type of polymers.They melt/soften when heated.There are no bonds between polymer chains.Strong intermolecular forces ensure that the structure is solid at room temp.These forces are overcome with heating
What are giant covalent substances
-Solids,atoms covalently bonded together in a giant lattice
-High melting/boiling point-strong covalent bonds
-Mostly don’t conduct electricity
-Diamond,graphite,silicon oxide
diamond
in diamond each carbon is joined to 4 other carbons covalently.its very hard has high melting point and doesnt conduct electricity.
graphite
in graphite, each carbon is covalently bonded to 3 other carbons, form layers of hexagonal rings which have no covalent bonds between the layers.
How can layers in graphite slide over each other
the layers can slide over eachother due to no covalent bonds between the layers, but weak intermolecular forces meaning graphite is soft and slippery.
How are graphites similar to metals
one electron from each carbon atom is delocalised. this makes graphites similar to metals because of its delocalised electrons. it can conduct electricity unlike diamond
What is graphene
single layer of graphite,strong(atoms tightly bonded).
What are fullerenes
carbon can also form fullerenes with dif numbers of carbon atoms. molecules of carbon atoms with hollow shapes. they are based on a hexagonal rings of carbon atoms but may also have 5 or 7 carbon atoms.