Topic 1 Flashcards
covalent bonds
two non metals share a pair of electrons
dot and cross diagram
+ shows how electrons are shared
+ formula of compound can be worked out from the diagram
- makes it look like the dot and crosses are different electrons from each atom
- only shows outer electrons
compound
two or more elements/ atoms chemically bonded
proton
+1
1
nucleus
neutron
0
1
nucleus
electron
-1
1/2000
shells around nucelus
metals loose electrons to form
cations
non metals gain electrons to form
anions
mendeleev
- arranged the periodic table by atomic number
- left spaces for undiscovered elements
- arranged in grouped and periods
- metals on right and non metals on the left
- made predictions bases on similar chemical and physical properties
Isotopes
Same atomic number but different mass number due to the number of neutrons being different
Ionic bond
Metal and non metal gain/ loose electrons
diatomic
H2
N2
O2
F2
Cl2
Br2
I2
Cl2
simple molecular structures
dont conduct electricity
low melting and boiling point
differences between diamond and graphite
- diamond is expensive and rare
- graphite is dull but diamond is clear
- different lattice structures
similarities between diamond and graphite
- made from pure carbon
allotropes
different structures made up of the same element such as diamond and graphite
diamond structure
- consists of pure carbon with each carbon atom forming 4 covalent bonds with 4 other carbon atoms
- giant lattice
- high melting/ boiling point
- very hard
- no conductivity : no free electron
Graphite structure
- each carbon atom covalently bonds with 3 other carbon atoms
- the remaining electron is delocalised and is free to carry charge
therefore can conduct electricity - high softness : layers can slide over each other easily as they are held by weak intermolecular forces
- very high melting point (still a giant lattice)
why is diamond used for cutting tools
very hard
why is graphite used to make electrodes
free electrons can carry charge
why is graphite used as a lubricant
the layers of carbon atoms can easily slide over each other as the intermolecular forces so little energy is needed to break them they are weak making it very slippery
allotropes of carbon examples
buckminsterfullerene
C60
graphene
diamond uses
- cutting metals and glass
- demand in jewlery
graphite uses
- pencil led
- lubricant
- electrodes
graphene
- one atom thick
- strong covalent bonds
- used in sports equipment since its light and durable
- used in electronics
C60
- tubular or spherical
models - low melting points ( weak intermolecular forces)
- drug delivery in the body
- simple molecule
- hexagons and pentagons
Nanotubes
- tensile strength
- used in nanotechnology and electronics
polymers are made up of
small molecules called monomers joined together by covalent bonds
Metallic bonding
The strong electrostatic attraction between a sea of delocalised electrons and a cation
metal properties
- ductile ( arranged in regular layers allowing then to slide over each other)
- shiny
- malleable
- conduct electricity
ball and stick model
+ shows the bonds between each atom
+ shows the 3D structure so we can see how the atoms are arranged in relation to each other
-doesn’t show teh relative sizes and distances between them
- the bonds aren’t really like sticks
space filling model
+ shows 3D structure so we can see hoe atoms are arranged in relation to each other
+ more accurately represents the relative sizes and distances in relation to each other
- doesn’t show how the bonds are formed
displayed formula
+ shows chemical bonds
+ formula of compound can be worked out from the diagram
- doesn’t show relative sizes or distances of atoms or bonds
law of conservation of mass
mass is never lost or made in a chemical reaction in a closed system
mass of reactants = mass of products
mr atomic or mass
use the MASS number
mass of product
- check balanced
- known and unknown
- mr
- divide by smallest mr
- times by given mass
solvent
something able to dissolve other substances
solute
a substance that is dissolved in a solvent
solution
mixture formed when solute dissolves into solvent
concentration
volume of solute (g) / volume of solution (dm3)
1dm3
= 1000cm3
if volume is given as cm divide by 1000
moles
= mass/mr
calculate the number of moles
- mr
- moles = mass/ mr
calculate the mass of X moles
- mr
- number of X x mr
shells atomic or mass
atomic - less
empirical vs molecular formula
The empirical formula of a compound is the simplest, whole number ratio of atoms of each element in a compound.
The molecular formula shows the actual number of atoms of each element present in a compound.
why a lid ..
so that no produect escapes
why is dye used
makes cell more visable
Which process moves alcohol from the blood into the liver cells?
diffusion
