Topic 1 States + Periodic Table +Electrons Flashcards
Describe a gas
Particles are random and far apart
The particles are fast in all directions
Describe a liquid
Particles are random and close together
They move around each other
Describe a solid
The particles are regular and close together
They vibrate around a fixed position
How does a solid go to a liquid then to a gas?
Melting then the liquid evaporates(boiling)
How does a gas go to a liquid then to a solid?
The gas condenses and then the liquid freezes
How does a solid go to a gas and vice Versa?
Solid - gas is sublimation
Gas - solid is deposition
How are particles attracted to each other?
By weak forces of attraction (attractive forces)
What happens when a liquid is Evaporated?
The attractive forces between the particles are overcome because energy is transferred from the surroundings to the particles
Why does the temperature stay constant when a solid is changing state to a liquid?
The substance is still being heated but the added energy is making the particles break away from their fixed arrangement
Why does the temperature stay constant when a liquid is boiled?
Because the particles are escaping from the liquid to form a gas
If the substance is below melting/between melting and boiling/above boiling, what state will it be?
Solid/Liquid/Gas
What is a pure substance?
It cannot be changed
The substance is the same in all parts (when a piece of substance is looked at)(the same fixed composition in all parts)
Can’t separate using physical methods
What is a mixture?
Contains elements/compounds that are not chemically joined together
Can use physical methods to separate the substance
What is a solution?
A mixture of dissolved substances (I.e. solutes) in a liquid called the solvent
How do you create crystals?
Mix the solution together
Line a funnel with filter paper. This allows the solvent and solutes to pass through and collect in the beaker. This is the filtrate.
Insoluble substances that can’t get through are the residue
A Bunsen burner is then used to heat the evaporating basin (which is over a beaker filled with boiling water)
You then stop heating when crystals start to form and leave the evaporating basin in a dry place to allow the crystals to form/crystallise.
How can you reduce the risks during crystallisation?
Wear goggles
Not to overheat the basin as hot crystals may spit out or change crystals chemically
What is chromatography?
A technique used to find out which coloured compounds a mixture contains
Why is paper chromatography a simpler technique?
Some compounds dissolve better in the solvent (water) than others
What is the mobile phase and what does it do?
The solvent - when it moves along the paper, it carries the different substances in the mixture at different speeds, separating them.
What is the stationary phase?
The paper (contains it)
What is the chromatogram?
The paper with all separate components
How do you calculate the rF value?
Distance moved by spot / distance moved by solvent
What is paper chromatography used for?
Distinguishing between pure and impure substances
Identifying substances by calculate Rf values
Why do you use pencil?
Because it won’t be carried up by the solvent
What is distillation?
Separating a liquid from a mixture by evaporating the liquid and then condensing it.
Why is the liquid pure?
When the liquid is heated, only the water evaporates and turns to gas as the solids have a higher boiling point and are left behind. The gas( water vapour) is then condensed and collected elsewhere and because it is purely water, the liquid is pure.
What is fractional distillation?
Separating two or more liquids by first evaporating the liquid with the lower boiling point and collecting it as vapour first
How does it work?
The mixture will be separated into different fractions. The first fraction to be evaporated will be the one with the lowest boiling point.
How are the different fractions collected? (Use equipment)
A column is fixed above the distillation flask.
When the flask is heated, the hot vapour rises up the column
The water vapour will then condense when it hits the top of column (at first it won’t be collected)
Therefore, it is hottest at bottom of column but coolest as you for further up
The fraction with the lowest boiling point will reach the top of the column first and the vapour will then pass into the condenser and this will carry on with the different fractions when the temperature rises.
Why is fractional distillation useful?
It separates the different fractions in crude oil
Makes alcoholic drinks e,g, whiskey
To separate gasses in the air (once they’ve cooled down and been condensed into a liquid)
How can you set up a chromatography experiment and a distillation experiment for ink?
Distillation -x-
Ink should be in a flask which is being heated by Bunsen burner.
The gas will rise to top and travel through a delivery tube and into a boiling tube in ice cold water. This will condense the gas back into a liquid.
Chrome -+-
Draw a pencil line about 2cm from bottom of paper
Add a small spot of ink to line and add water to a container of 1cm depth
Place the paper into the container/water but make sure the paper is up straight
Take the paper out before it reaches top and mark the end of the solvent using a pencil and leave to dry
Measure the distance the solvent/spot have moved to calculate the Rf value
How to purify sea water (simply)?
Heat the water and collect the water vapour
Then cool the vapour so it condenses back into a liquid which will be pure/ water without containing the dissolved salts
What is chemical analysis?
Using chemical reactions or sensitive machines to identify and measure the substances in a sample
How is water made so it is suitable for drinking?
Water from a water source is first put into a sedimentation tank which allows small particles to settle out
It then goes into the filtration tower contains sand and gravel. The water is filtered through the sand and gravel so any insoluble substances are left behind
Chlorine is then added to kill bacteria or other microorganisms in the water before being stored in a water tower
What can fresh water contain?
Leaves and twigs
Insoluble particles e.g. grit
Soluble substances like salts and fertilisers
Bacteria and other micro organisms
What was Dalton’s atomic theory?
He thought all matter was made up of small particles called atoms
Atoms are tiny and cannot be created or destroyed
The atoms in an element are identical
What is the charge and mass of a proton?
Charge is +1 and mass is 1
What is the charge and mass of electron?
Charge is -1 and mass is 1/1835 or 1/1840 or negligible
What is the charge and mass of neutron?
0 charge (neutral) and 1 mass
What was the gold foil experiment?
He fired tiny positive particles at a thin piece of gold foil
Surprisingly, most of the particles passed straight through
However, some deflected it and some bounced back
What is an isotope?
And element with the same atomic number but different mass number
How do you calculate the rfm of isotopes?
(% x rfm) + (% x rfm) all divided by 100(no. Of atoms)
How did Mendeleev organise the periodic table?
He arranged elements in increasing relative atomic masses but left gaps
Also tried to group elements if they had similar chemical properties
What did Henry Moseley discover?
The atomic number is the same as the number of protons in a nucleus
How is the periodic table arranged now?
Arranged in order of increasing atomic number (not rfm)
Elements in a row or period are increasing in atomic number
Elements with similar properties are in the same column or group
Non-metals on right of table
How many electrons can the first two shells hold?
1st shell 2
2nd shell 8
How is the periodic table related to the electronic configuration?
Number row = number of electron shells
Group number = number of outer electrons in outer shell (group 0 have full shell)
