Add Chemistry Flashcards
What is the mass number
The total number of protons and neutrons in an atom
What is an isotope
An atom with the same number of protons but a different number of neutrons
What is the atomic number
The amount of protons in the atom
Which one is the mass number
The top number
Which one is the atomic number
The bottom number
How do you find out how many neutrons there are in an atom
Mass number-atomic number
What is an isotope
An atom with the same amount of protons and electrons but with a different number of neutrons
What is the only diferance that can exist between two isotopes
One being radioactive and the other not
How do you work out relative atomic mass
(%of isotope 1Xmass of isotope1)+(%of isotope2Xmass of isotope 2)
Ans/100
Who invented the law of octaves
John newlands
Give an example of issues Mendeleev had with putting attoms in order of their atomic mass
Iodine had a lower atomic mass than tellurium so it should come before tellurium. To get iodine in order with other elements with similar property’s he had to put it after tellurium, breaking his own rules
How did Henry Mosley propose to solve problems caused by ordering atoms by atomic mass
Using atomic number instead
What is the ordering value used along the rows of the periodic table
Atomic mass
What is eh period number in the periodic table
The vertical number from lithium down to francium
What does the period number show
The number of shells used up by the electrons
How do you draw out the electronic structure
Have how many electrons on each shell with commas between them
Don’t confuse with dot and cross diagrams
Why are ions
Electrically charged particles formed when atoms lose or gain electrons
What sort of ions do metals form
Positive
What sort of ions do non metals form
Negative
What are the strong electrostatic forces between oppositely charged ions called
Ionic bonds
What are the forces that hold ionic bonds together called
Electrostatic forces
How so you work out the charge of a metal ion
It is equal to the group number it is in
How do you work out the charge on a non metal ion
The group number minus eight
What does it mean if there is an ide at the end of the compound
There are only the atoms in the compound present
What does it mean if there is an ate at the end of the compounds name
There is an oxygen present
In what structure are ionic compounds arranged
Lattice
What does a lattice structure result in the formation of
A crystal
What do the strong ionic bonds in a crystal lattice cause
Very strong compounds and high boiling points
Why can solid ionic compounds not conduct electricity
The ions are held firmly in place
Why can molten ionic compounds move
Because the charged ions are free to move
Can a solution of ionic compounds conduct electricity
Yes
What is sodium chlorides melting point
800degrees Celsius
What is magnesium oxides melting point
2800 degrees c
What makes nacl a weaker bond than Mgo
Mgo has two pos and two neg charges where as nacl only has one of each
What is an example of a precipitation reaction
AgNO3+NaCL->AgCL+NaNO3
Silver nitrate(soluble)+sodium chloride(soluble)-> silver chloride(insoluble) + sodium nitrate soluble
A use for an insoluble salt
Barium sulphate-to show up on X-rays
Why does barium sulphate not kill people when they ingest it
It is toxic but is also insoluble so can not enter the blood stream
Steps of doing a flame test
Four
Dip a clean flame test loop in the sample solution
Hold a flame test loop at the edge of a Bunsen burner flame
Observe the changed colour of the flame and decide which metal it indicates
Clean the loop in acid and rinse with water, then repeat steps 1 to 3 with a new sample
Barium a flame test colour
Pale green
Calcium a flame test colour
Yellow red
Coppers flame test colour
Green blue
Lithiums flame test colour
Red
Sodium a flame test colour
Orange
Potassium flame test colour
Lilac
What are the uses of a flame test
Confirming the results of a precipitation test
What is an anion test
Detecting ions present in water through precipitation reactions
What is the colour of the precipitate formed by a soul fire ion and barium chloride
Barium sulphate is formed, it is white and insoluble
What do you use to test for halide ions in water
Silver nitrate, all halide ions form precipitates
What colour precipitates do
Chlorine bromine and iodine ions when in a precipitation reaction with silver nitrate
Silver chloride white precipitate
Silver bromide cream precipitate
Silver iodide pale yellow precipitate
How do you test for carbonates
Acid is added to the carbonate
If carbonate carbon dioxide will bubble off, test this by running it through lime water
What is spectroscopy
When atoms are heated they all give off light, a proximity is used to split this light into a spectrum. Each element has it’s own distinctive light spectrum
What is the process in which the light given off by an unknown element is analysed
Spectroscopy
How was helium discovered
By studying the kin spectra emitted by the sun
Which elements could not have been discovered without the use of spectroscopy
Rubidium
Caesium
Helium
What happens to the group one metals melting point as you go down the group
The melting point decreases
What happens to the density of group one elements as you go down the group
They become more dense
in which direction do group one metals change their reaction speed
Speed and violence of the reaction increases as you go down the group
What happens to lithium in a cold water reaction
It floats, it fizzes and becomes smaller until it disappears
What is the word and letter equation of a lithium reaction with water
Lithium+water->lithium hydroxide+ hydrogen
2Li+2H2O->2LiOH+H2
Describe the reaction sodium has with cold water
Fizzes rapidly
Melts to form a ball
Hydrogen produced May burn with an orange flame before the sodium disappears
What are the word equation and letter plus number equations of the reaction between water and sodium
2Na+2H2O->2NOH+H2
Sodium+water->sodium hydroxide+hydrogen
Describe the reaction between potassium and water
Five
The metal melts and floats
It moves around very quickly on the water
The hydrogen ignites immediately
The metal is set on fire with a lilac flame and sparks
There is sometimes a small explosion at the end of the reaction
What is the word equation and letter plus number equation between potassium and cool water
Potassium+water->potassium hydroxide+water
2k+2H2O->2KOH+H2
Why does the reactivity go up as you go down the group of alkaline metals
The number of electron shells increases so increases distance between the single outer electron and the nucleus the attraction from the positive nucleus to the negative electron is less making it easier to remove the outer electron to form an ionic bond
What happens to the halogens boiling temp as you go down the group
Their boiling temp increases
What is the trend in the state of group 7 matter as you go down the group
They move from solid liquid then gas
What happens to the colour of the halogens as you go down the group
They get darker
What happens to the reactivity of halogens as you go down the group
It reduces
What is the product of a halogen reacting with a metal
A metal halide
Uses of halogens
They are bleaching agents
Chlorine is used to bleach wood pulp white for paper
They kill bacteria, chlorine is added to drinking water to make it safe to drink
What happens in a displacement reaction
a more reactive element replaces a less reactive element in a compound
Give an example of a displacement reaction
When chlorine is added to sodium bromide solution the chlorine replaces the bromine
The solution turns brown due to the excess bromine in the mixture
What is the word for chemically unreactive
Inert
What Are five things noble/inert gases have in common
Non metals
Unreactive
Colourless
Are monatomic-exist as single atoms
Uses for helium
1
Balloons and airships
Less dense than air so it causes stuff to float
One use for neon
Used in advertising signs
It glows when electricity is passed through it, different coloured neon lights can be made by filling the inside tube with different chemicals
Use for argon one
Used in light bulbs
The oxygen in air would burn the filament if it where filled with air
What’s the name for a reaction that takes heat from the surroundings
Endothermic
What’s the name for a reaction that releases heat into the environment
Exothermic
What is an example of an Exothermic reaction
Neutralisation reactions
Combustion
Give two examples of an endothermic reaction
Electrolysis
Photosynthesis
What sort of energy process is bond breaking
Endothermic
What sort of energy process is bond making
Exothermic
What makes the difference between a reaction being Exothermic or endothermic
If more bonds are made than broken it is Exothermic
If more bonds are broken than made it is endothermic
What is the equation for the calculating the energy transferred
Energy transferred=mass of water heated x specific heat capacity of water x temperature rise
What are the two ways to measure the rate of reaction
Measure the rate in which the reactant is used up
Measure the rate in which the product is formed
Things to measure in a rate of reaction equation
Prior
Two
The mass of substance
The volume of gas
What is the equation for rate of reaction
Rate of reaction=amount of reactant or product/time taken
What are the five things that increase the rate of reaction
The temperature envreasing
The concentration of a dissolved reactant being increased
The pressure of a reactant gas being increased
Solid reactants being broken into smaller pieces
A catalyst being used
What is the minimum energy required for particles to react called
The activation energy
Why are catalysts important in industry
They reduce costs
How do catalysts work
They lower the activation energy needed
Which catalyst is used in an nitrogen+hydrogen->ammonia reaction
Iron or platinum
Which catalyst is used to make dilutive acid
Vanadium oxide
What do catalytic converters do
Increase rate of reaction between carbon monoxide and unburnt fuel from exhaust gases with oxygen in the air using catalysts (platinum)
How do you work out the relative formula mass of a compound
Add their relative atomic mass together
What is the relationship between the mass of reactants and the mass of products
Mass of reactants=mass of products
How to calculate relative atomic mass
(%Of isotope 1 x mass of isotope 1) + (%of isotope 2 x mass of isotope 2)
Two property’s of simple molecular bonds
Low melting and boiling points because the weak inter molecular forces break down easily
Non conductive they don’t have any free electrons
Property’s of giant molecular bonds
Very high melting points because a lot of strong covalent bonds must be broken
Variable conductivity diamond does not conduct electricity silicon is semi conductive graphite contains free electrons so it does conduct
What are the three allotropes of carbon
Diamond graphite and buckminsterfullerene
What are the uses if diamond and why
Hard and high melting point so is used in cutting tools
Shines so is used in jewellery
Uses of graphite and why
Pencil leads
Graphite is in layers which slip off of the lead and onto the paper very easily
Component of many lubricants
Has a high melting point and is insoluble in water and is conductive so it makes it suitable as an anode and cathode in electrolysis
How many bonds does carbon form in a diamond
4
How many bonds does graphite form
Three
What piece of equipment can be used to deprecate two im miscible liquids like oil and water
A separation funnel
The liquids are left to separate then a tap at the bottom is run until the lower liquid has left the mixture
How are miscible liquids seep rated
Fractional distillation
How air is seep rated into different fractions through cooling
Four steps
Water vapour condenses and is removed using absorbent filters
Carbon dioxide freezes at minus seventy nine degrees
Oxygen liquified at minus one hundred and eighty three degrees
Nitrogen liquifies at 196 degrees centigrade
Nitrogen and oxygen are then separated through fractional distillation
What is chromatography
The separation of liquids on a piece of paper
This is suitable for dyes and food colouring
How do you find out the rf value of a chemical
Rf can be identified by the equation
Distance moved by compound/distance moved by solvent
What sort of bond holds together metals
Metallic bonds
What do the transition metals all have in common
Seven
They form coloured compounds
They are good conductors of heat and electricity
They are are malleable
They are less reactive than alkaline metals
They have high melting points except for mercury
They are usually hard and tough
They have high densities
How do you work out the percentage by mass of a component in a compound
(Mass number of element/mass number of whole molecule) x 100
Formula for calculating percentage yield
(Actual yield/theoretical yield) * 100
What are the three things that cause a non on hundred percent yield
Incomplete reactions
Losses during the practical
Unwanted by~products being produced
What are three problems with waste products
Have no commerce benefits
Are difficult either socially or environmentally to dispose of
Are expensive to dispose of
What does a reaction that is economically favourable have
High percentage yield
By products are commercially useful and are sold
The reaction occurs are a suitable rate
What is an example of an economically favourable reaction
The production of ammonia
N2+3H2->2nh3
