Unit 1 - Atomic Structure And Periodic Table Flashcards
What is isotopes
Different form of the same element same number of protons but different number of neutrons
Relative mass of neutron
1
What is a mixture
Two or more elements or compounds mixed together
What is filtration
Separates insoluble solids from liquids
What is distillation
Separate solutions
What did jj Thompson come up with
Discovered electron , plum pudding model
What did John dalton discover
Atoms
What did Rutherford discover
Came up with alpha and beta particles and nucleus model
What did Neil Bohr discover
Suggested that all atoms were contained in shells
Who first developed the periodic table
Mendeleev
Properties of transition metals
Good conductors of heat and electricity
High density
High melting point
Form ions with different charges
What metals are in group 1
Alkali
Properties of alkali metals (group 1)
Low density, increasing reactivity as you go down, low melting and boiling pints
What is group 7 also known as
Halogens
Properties of halogens
Less reactive as you go down, high belting and boiling points
What did Chadwick discover
The neutron and isotopes have the same number of proteins and electrons but with different number of neutrons
What is a mass number
No of proteins and neutrons
Why do alkaline batteries stop working
A reactant is used up
Why can alkaline batteries not be recharged
The reaction is not reversible
Why did Mendeleev periodic table become more widely accepted
-Mendeleev had predicted properties of missing elements
- elements were discovered filled gaps
- properties of these elements matched his predictions
What is the modern name for the atomic weight
Relative atomic mass
What do you see when sodium reacts with chlorine
-Flame
-white solid forms
What ion do all acids produce in aqueous solutions
H+
Explain why carbon nanotubes conduct electricity
Contain delocalised electrons
So electrons can move through nanotube
Relative mass of neutron
1
Relative mass of proton
1
Why is the mass number different in two isotopes
Different number of neutrons
Relative mass of electron
0.0005
Explain why the alpha particle scattering experiment led to a change in model of the atom from the plum pudding model
-most alpha particles passes through gold foil
-so most of atom is empty space
-some particles were deflected
-so atom has a positively charged nucleus
Limitation of using a dot and cross diagram
Only 2 dimensional
Explain why ammonia has a low boiling point
-simple molecular structure
-has weak intermolecular forces
-so little energy needed to overcome the force
Control variables in electrolysis experiment
-temperature of solution
-size of electrode
-distance between electrodes
Hydrogen fuels can be used to power steam trains. Suggest why
- hydrogen is oxidised to produce water
- water is produced as steam
Explain why a mixture is used as the electrolyte
-Mixture has low melting point
-so less energy needed
Why must the positive electrode be continually replaced
-the electrode could react with oxygen
-the electrode is carbon
-so carbon dioxide is produced
Explain why sodium chloride solution cannot be used as the electrolyte to produce sodium metal
Hydrogen gas would be produced instead of sodium
Because sodium is more reactive than hydrogen
Why should hydrogen be burned off
To prevent it escaping into air
Because hydrogen is explosive
How could student separate insoluble silver iodide from mixture at end of reaction
Filtration
Why are reactions why a high atom economy used in industry
For economic reasons
Describe change Bohr made to nuclear model
Electrons orbit nucleus
And electrons are at specific distances from nucleus
Why did Mendeleev reversed order of some pairs
So properties matched rest of group
Advantages of using hydrogen fuel cells
No toxic chemicals to dispose at end of cells life
Takes less time to refuel
Disadvantages of the simple particle model for hydrogen gas
-Only two dimensional
-does not show the movement of particles
Why should halogen gas experiment be done in a fume cupboard
Halogen is toxic
Why does reactivity decrease as you go down the halogen group
The outer shell becomes further from the nucleus
So nucleus has less attraction for outer shell
So electron is gained less easily
Why is burette used in the RPA
Can add drop by drop
More accurate than measuring cyclindor
What is an element
Substance that is made up of only one type of atom
Roughly how many different elements are there
100
What is a compound
A substance made from more than one type of element chemically bonded together
How are compounds represented
combining the chemical symbols of the 2 elements (Na and O) to create the chemical formula Na2O.
What is a mixture
Contains two or more substances not chemically bonded together
Does the properties of each substance in a mixture change
Being part of mixture doesn’t change the chemical properties of the substances that are in it
5 processes that can be used to separate mixtures
Filtration.
Crystallisation.
Paper Chromatography.
Simple Distillation.
Fractional Distillation.
What can crystallisation be used to separate
Used to dissolve a soluble solid from a liquid
Process of simple distillation
Place our solution with our dissolved solid into the flask, heat the solution with a Bunsen burner. Heat the solution until it boils. The liquid starts to evaporate turning into a vapour. Vapour rises up the glass tube the flask into the condenser (condenser is cold as a result of cold tap water circulating around it). This cause the vapour to condense turning back to a liquid. We collect the liquid in a beaker and left with crystals in the flask.
Ways to used simple distillation in real life
Can be used to make drinking water from sea water
Disadvantage of simple distillation
Great amount of energy is required for simple distillation
What is simple distillation used to separate
A solvent from a solution
What is filtration used to separate
Seperates an insoluble solid from a liquid
Process of filtration
Pouring our mixture into the filter paper, the solid material cannot pass through the paper so it’s trapped.
Process of crystallisation
Leave the solution for a few days for the solution to evaporate. This will leave behind solid crystals
How do you make crystallisation happen faster and a disadvantage of doing it
By gently heating our solution to evaporate the water. However certain chemicals will break down if we heat them
Example of filtration (RPA)
Can be used to separate copper oxide from sulphuric acid
Example of crystallisation in real life
Crystallisation of water to form ice cubes and snow
What does paper chromatography allow us to do
Separate substances based on their different solubilities
Process of paper chromatography
Draw a pencil line near the bottom, we put a dot of as many colours we can fit on our pencil line. Place bottom of paper into a solvent. The solvent will rise up the paper and carry the ink up with it
What phase do we call the paper in paper chromatography
The stationary phase because the paper does not move
What phase do we call the solvent in paper chromatography
The mobile phase because the solvent moves
What will a pure compound produce in photo chromatography
A single spot in any solvent
What will the compounds in a mixture look like in photo chromatography
Will separate into different spots depending on the solvent
Why do we draw our starting line for photo chromatography in pencil
If we drew the line in pen, the ink could dissolve in the solvent and move up the paper
What is required in fractional distillation in the mixture of solutions
That they have different boiling points then it will work
What does fractional distillation separate
Two liquids
Process of fractional distillation
Heat our mixture, both liquids will start to evaporate but the one with the lower boiling point will evaporate easier. Vapours move up the fractionating column, they then condense and drip back into flask to evaporate again. This repeated process will increase amount of the lower boiling point chemical in fractionating column. The lower boiling point chemical will then mostly be the one being collected in the beaker
Disadvantages of fractional distillation
Won’t be useful for separating large volumes of liquid, might need to carry out several round of fractional distillation if boiling points are close together
Which particles have the same relative mass
Proton and neutron
One reason why platinum may be used for jewellery
Un reactive
Observations when sodium is added to water
Bubbles, moves around, catches fire
What may lead to a scientific model being changed
New experimental evidence
What is the plum pudding model
Positive ball of charge with negative electrons
What is the alpha scattering experiment
Fired alpha particles at a thin layer of gold foil
What did scientists discover by the alpha scattering model
-Most of alpha particles went straight through the foil therefore atoms are mainly empty space
-some alpha particles were deflected so the centre of the atom must have a positive charge
-because some alpha particles bounced back the mass of the atom must be concentrated in the centre
Differences between plum pudding model and nuclear model
-nuclear model have mainly empty spaces however plum pudding has none
-nuclear model electrons orbit nucleus however plum pudding model electrons are embedded in the mass of positive charge
Radius of an atom
0.1 nm or 0.0000000001 or 1 × 10 -10 m)
Radius of a nucleus
1 × 10-14 m
Relative the size of atoms to objects that can be seen in real life
If the nucleus were the size of a blueberry, the atom would be about the size of a football stadium
How to calculate relative atomic mass
(Mass number of isotope 1) + (mass number of isotope 2 x percentage abundance of isotope 2) / 100
How are elements arranged in the periodic table
In order of increasing atomic number
Problems with the early periodic table
Early periodic tables were incomplete, since many elements were unknown.
Physical properties of metals
Shiny , high melting points, good conductors of electricity, good conductors of heat, high density, malleable
What does malleable mean
Capable of being hammered or pressed into a new shape without being likely to break or return to the original shape
Properties of non metals
Dull, low melting points, poor conductors of electricity, poor conductors of heat, low density, Brittle
What does brittle mean
Easily broken
Describe the trend in boiling point going down group 0
Boiling point increases
How quick does alkali metals react with oxygen
The further down the group the quicker it reacts
What happens when alkali metals react with water
Alkaline solution produced
Gas being produced
Bubbles
Fizzing
Name of process when an acid and alkali react
Neutralisation
Litmus paper is an example of a what?
Indicator
Which ions do all acids produce in aqueous solution
H plus
Why are alloys harder than pure metals
Atoms are different sizes, this distorts layers, so layers can’t slide over each other as easily as a pure metal
Why is rubidium more reactive than potassium
Outer shell further from nucleus
So less electrostatic attraction between nucleus and outer shell
So electrons are more easily lost
