Studied by 4 peopleWhat is the difference between an atom and a molecule?
An atom is only one atom
A molecule is two or more atoms bonded together.
Filtration
What does filtration seperate?
A liquid and an insoluble solid
What does crystallisation seperate?
A soluble solid in solution
chromotography
What can chromotography seperate?
A mixture of coloured compound
Distillation
What does distillation seperate?
2 liquids
Why is it important that pharmaceutical drugs are as pure as possible?
This reduces the chance of unecessary side effects and helps to ensure an accurate dose in each tablet.
How do we test if a substance is pure or not?
The purity of something can be tested using data from its melting and boiling point.
What is the effect of impurity to the boiling of the substance
The presence of an impurity usually lowers the melting point and raises the boiling point
evidense of a chemical reaction:
precipitate
color change
gas
temperature change
not easy to reverse
What is a physical change?
Whe no new substance is formed and the cnage is easily reversed
EXP: phase transformation (melting, boiling)...
What is a chemical change?
When a new substance is formed, but it is difficult to reverse
EXP: burning, rusting, any reaction
What is an element?
Substance that only has one type of atom
What is a compound?
Pure substance made up of two or more elements bound together
What is a mixture?
Matter that formed from two or more elements/ compounds physically intermingled
What is a atoms goal in life?
To get a noble gas outer shell configuration
What is an atom made up of?
Electrons, a nucleus (full of protons and neutrons)
Whats an electrolyte?
A liquid or solution that conducts electricity by movement of ions
Atomic number
What is the Atomic number?
The number of protons in the nuclues of an atom
mass number
What is the mass number?
the total number of protons and neutrons in a nucleus
isotope
What are isotopes?
Atoms that have same number of protons but different numbers of neutrons
Ion
What is an ion?
Ions are particles formed when atoms gain or lose electrons
Ionic compound
In what kind of structure are ions held together?
A lattice structure, which is a regular arrangement of alternating positive and negative ions held together by electrostatic attraction.
Bonds between:
2 hydrogen
2 chlorine
water
methane
h and cl
2 nitrogen
c2h4
and carbondioxide
H-H
CL-CL
H-O-H
H-Cl
N=-N (triple bond)
H- -H
Cl=Cl
H- -H
O=C=O
Ionic compounds
Properties of ionic compounds
High melting and boiling points
Low volatility
Usually solid state
Usually soluble in water
Conduct electricity when molten or dissolved
(ions are free to move and carry charge)
Properties of Simple Convalent compounds
Low melting and boiling points; high volatility
More soluble in organic solvents than water
Do not conduct electricity
(no ions present)
What is a convalent structure?
Non-metals that share electrons
Graphite
Talk about Graphite
a form of carbon
each carbon atom is joined to three other carbon atoms, forming a giant convelant structure
these layers formed slide over each other, so it is quite soft.
it is used in pencils, and as a lubricant
it conducts eletricity
What is a lubricant?
a substace used to reduce friction between two surfaces
Talk about Diamond!
A form of carbon
Each carbon atom is joined to four other carbon atoms
As a result, diamond is very hard and has a high melting point
It does not conduct electricity
Talk about Silica (silicon IV oxide)
Silica, which is found in sand, has a similar structure to diamond.
It is also hard and has a high melting point.
But it contains silicon and oxygen atoms, instead of carbon atoms.
What is relative atomic mass?
Is the average value for the isotopes of the element
For example: for chlorine it is 35.5 because it contains two different isotopes
What is relative molecular mass? (M = molecular mass = mass of 1 mole)
Is the sum of the relative atomic masses
eg, what is relative atomic mass of water (H2O)?
1+1+16=18
What is a mole?
A unit for amount of substance.
One mole contains avogrado's number or particles (atoms, molecules, ions or electrons) in a substance
What is the molar gass volume at room temperature and pressure?
24 dm^3 or 24000 cm^3
Moles formulas
moles = mass/molar mass
concentration of solution formula
conentration of solution= number of moles of solute dissolved/ total volume of solution
Remember trick- REDCAT
IN electrolysis, where does reduction take place?
reduction always happens at the cathode
Remember trick- ANOX
IN electrolysis, where does reduction take place?
Oxidation always happens at the anode
what is ELECTROLYSIS?
The chemical effect of electricity on ionic compounds, causing them to break up into smaller, simpler substances, usually elements
Note
Flashcard