Atomic Structure and periodic table Flashcards
How can you separate a soluble solid from a liquid?
- Evaporation
- Crystallisation
What is filteration?
Separating insoluble solids from liquid
Problems with evaporation
- Can cause solids to decompose when heated
- Called thermal decomposition
What does filter paper have?
small holes that are large enough to allow liquid particles to move through, but too small to allow solids through. This separates the solids from the liquids in filtration.
What is simple distillation?
Separates liquid from solution
Equipment for simple distillation
- Flask w/ solution
- Bund on flask
- Thermometer through bung
- Condensor with water jacket (cold)
- Beaker to capture
- Bunsen burner under flask
What is fractional distillation?
Separating mixtures of liquids
What does a fractionating column have?
- Full of glass rods - prodive large SA
- Tall - cooler at top than bottom
Compared to group 1, how are the transition elementd?
- Harder
- Stronger
- High melting points (not mercury)
- Higher densities
- Les reactive and dont react as vigourosly with o2 or water
Propertie of chromium
- Lustrous
- Brittle
- hard metal
Properties of manganese
- Hard
- Very brittle
- Difficult to fuse
- Easy to oxidise
Properties of iron
- Good conductor
- Rusts easily in air
- Strong
- Ductile
- Malleable
Typical properties of transition metals
- Useful as catalysts
- Form coloured compounds
- Have ions with many diff charges
- Hard and strong metals
- High density
- High melting points
- Less reactive than group 1
Properties of copper
- Highly ductile
- Conductive
- Malleable and soft
Properties of nickel
- Hard malleable
- Ductil
- Good conductor of heat and elect.
Uses of Gold and why
- Jewellery - doesnt react with air or water at room temp, malleable
- Electrical connectors
Properties of cobalt
- Brittle
- Hard high melting point
Uses of silver and why
- Jewellery - doesnt react with air or water at room temp
- Printed circuit boards and electrical contacts
Uses of copper and why
- Electrical wires
- Printed circuit boards
- Water pipes - doesnt react with water at room temp, can be hammered into a shape
Uses of iron and why
- Building material like bridges, buildings, ships,cars - strong, sheets easil shaped, cheaper than other metals
- Catalyst in the chemicl industry eg Haber process - increases rate of certain reactions, unchanged
Uses of chromium and why
- To coat other metals like iron on cars and bicycles - stays shiny when polished, resistant to corrosion
- Catalyst in the chemical industry - increases rate of reaction
Features of group 1 alkali metals
- Soft metals
- low melting points
- low density
- reactive rapidly with o2, chlorine and water
- form 1+ charge
What colour is iron (111) oxide?
Red
What colour is manganese (11) chloride?
Pink
What colour is chromium (111) chloride?
purple
What colour is copper (11) sulfate?
Blue
What happens when potassium reacts with water
- Flame
Gas produced
alkaline solution forming
metal + water
metal hydroxide + hydrogen
Why does reactivity increase as you go down group 1?
- Radius of atoms increase - greater distance between positive nucleus and negative electons - outer electron is less attracted to nucleus - easier to lose
- Outer electron is repelled by electrons in the internal energy levels - electron shielding - decreases attraction between nucleus and electron, as you go down, elements have more electrons in internal energy levels, increases shielding as you go down
Proporties of group 7
- Non- metals
- Diatomic - covalent bond
- Melting/boiling point increase as you go down
- Relative molecular mass increases (size) as you go down
2 elements that are gases in group 7
Fluorine and Chlorine
What is a liquid in group 7? Solid?
L = bromine
S = iodine
What is formed when group 7 elements when they react with other non metal elements
Covelent compounds that all have simple molecular structures
What is formed when halogens react with metals?
Ionic compounds
Describe fluroine at room temp
poisonous yellow gas
Describe chlorine at room temp
poisonous dense green gas
Describe bromine at room temp + what is it solution
- poisonous, dense,brown volatile liquid
- yellow in solution
Describe iodine at room temp + in solution
- shiny black solids
- solution = dark browm/red
What happens in group 7 as you go down?
- Become less recative
- High melting and boiling points
- high relativr atomic masses
What happens as you go down group 1
- Increased recativity
- Lower melting and boiling point
- High relative atomic masses
What do alkali metals only react to form?
Ionic compounds - generally white soids that dissolve in water to form colourless solutions
Group 1 and water
- React vigourously
- Produce H2 and metal hydroxides - compounds that dissolv ein water to produce alkaline solutions
- Amount of energy given out by reaction increases as you go down
Group 1 and chlorine
- Vigoursly
- Form white metal chloride salts
- as you go down, becomes more vigourous
Group 1 and oxygen
- Form metal oxide
- Lithium = lithium oxide
- sodium = mixture of sodium oxide and sodium perioxide
- potassium = mixture of potassium perioxide and potassium superoxide
Properties of group 0 noble gases
- 8 electrons in outer energy level + 2 (He)
- inert, stable
- exist as monoatomic gase - single atoms
- colourless gases
- non flammable as inert
What happens as you go down groupp 0?
- Boiling points increase
- Increasing relative atomic mass
Why does boiling point increase as you go down group 0?
- Due to increase in number of electrons
- each atoms having a greater intermolecular forces between them
- Lots of energy needde to break them
Where are metals and non metals placed?
Metals = left side + centre
non metal - right
Proporties of non metals
- dull looking
- more brittle
- not always solids at room temp
- dont conduct electricity
- low density
What did John Dalton say?
- Atoms are solid spheres
- diff spheres made of diff elements
What did Thomson say?
- atoms werent solid spheres
- found electrons
- plum pudding model
What is the plum pudding model
- atom is ball of + charge
- negative electrons embedded
What did Dobereiner do?
- Noticed elements with similar chemical propoerties often occured in 3s
- eg lithium, na, k - metals that react rapidly in water
- called these triads
- scientists wondered if elemtents could be arraged into some logical order
What did John Newlands do?
newlands octaves
- arranged elements in order of increaasing atomic weight
- every 8th element reacts in a similar way
Why wasnt newlands law of octaves taken seriously?
- Problem = by always sticking to the exact order of atomic weight, sometimes elements were grouped together when they have diff properties
How did Mendeleev arrange table?
- Arranged elements in increasing atomic weight
- Switch order of specific elements - so it fit properties of others in the same group
- Left gaps for undiscovered elements
- He predicted propoerties of undiscovered elements based on other elements in same group
- Properties matched predictions
- Scientists accept
Diff between modern and Mendeleev periodic table
- Modern - ordered in order of atmoic number - protons - werent discovered
- Mendeleev - order of aotmic weight
- Modern - group 0 - not fully discovered back then
Prob with Mendeleev ordering in atomic weight
- can appear in wrong order due to presence of isotopes
What is the alpha scattering experiment? Why was it done?
- Test plum pudding
- Thin sheet of gold
- Fired alpha particles to foil
- Alpha particles - + charge
- Most went straight through
- Some deflected - changed dirction
- Some bounced straight back off gold foil
- replaced plum pudding with nuclear model
Why did most of the alpha p. go straight through?
- Atom is mostly empty space
- Plum pudding is wrong
Why did some alpha p. deflect?
- Centre has a positive charge
- alpha p is positive so its repelled and changes direction
Why did some alpha p. bounce back?
- centre of atom has a great deal of mass - nucleus
Describe nuclear model
- Positive nucleus
- empty space mostly
- electrons
What did Niels Bohr say?
- Electrons orbit nucleus at specific distances
- Accepted by other scientists experiment results
- we called it energy shells
What did Chadwick do?
- Found neutrons
- nucleus has neutrons
radius of atom
1 X 10-10m
radius of nucleus
1 X 10-14m
atoms in the same period have the same number of ?
shells
What are fullerenes?
- allotropes of carbon
- made by bending sheets of graphene into hollow structures
Why are nanotubes useful in electronics?
each carbon atom has 1 delocalised electron - carry charge
2 uses of fullerenes
- catalysts in chemical reactions
- delivery of medicines around body
Why are fullerenes useful catalysts?
high sa: v ratio
Why is carbon nanotubes useful in tennis racket frames?
high strengh to weight ratio
Are transition elements metals?
yes
Alkali metals characteristics
- low density
- low melting points
- soft metals
- react rapidly with oxygen, chlorine, water
- form ions with 1+ charge
Properties of transition elements
- Hard and strong
- high melting points except mercery (liquid at room temp)
- high density
- less reactive than alkali metals - useful for pipes (Cu)
- form ions with diff charges
- form coloured compounds, alkali makes white compounds
- form catalysts
- high density
What colour is iron III oxide?
Red
What colour is manganese II chloride?
pink
What colour is chromium III chloride?
purple
What colour is copper II sulfate?
blue
Name transition metals
- Chromium
- Manganese
- Iron
- Cobalt
- Nickel
- copper
What colour and ions does Chromium form?
- Cr 2+ = dark blue
- Cr 3+ = green
- Cr 6+ = orange
What colour and ions does Manganese form?
- Mn 2+ = pale pink
- Mn 7+ = vivid purple
- also forms 3+, 4+, 6+
What colour and ions does iron form?
- Fe2+ = pale green
- Fe 3+ = brown
What colour and ions does cobalt form?
- Co 2+ = salmon pink
- Co 3+
What colour and ions does nickel form?
- Ni2+ = green
What colour and ions does copper form?
- Cu2+ = blue
- Cu+
Why are transition metals used as catalysts
- they form a range of ions
- eg iron = in haber process
- eg vanadium used to produce sulfuric acid
Reactions with transition metals
- slow reactions
- less reactive than group 1
Differences between plum pudding model and nuclear model
- Nuclear model is mostly empty space
- Nuclear model - mass and charge conc in nucleus
- Nuclear model = electrons and nucleus separate
- Plum pudding - mostly positive charge
- Plum pudding - no shells/ orbitting electrons
Why does BP decrease in the haolgens as you go up?
- size of molecules increase
- so intermolecular force increases
- so more energy needed to overcome intermolecular forces
Why is it not correct to say that the boiling point of a single bromine molecule
is 59 °C?
BP is a bulk property
why are nanoparticles cheaper than fine particles?
nanoparticles have a greater SA to volume ratio so less can be used for the same effect
Why does ammonia have a low BP?
- its a small molecule
- weak intermolecular forces
- so little energy needed to overcome intermolecular forces
what shape is buckminiserfullerene
sphericla
uses of fullerenes
drug delivery, catalysts, lubricants
prediciting state of substance
if the given temp is below the melting point of substance, what state is it?
solid
why is graphene soft and slippery
weak intermolecular forces bwetween layered structure of hexagonal rings with weak forces between layers
Why are there delocalised electrons in graphite?
3 covalent bonds with each carbon atom - releases a delocaised electron
prediciting state of substance
if given temp is between the mp and bp what state
liquid
predicint state of substance
if given temp is above the boiling point?
gas
What happens when a solid is heated?
- particles gain more energy
- particles vibrate so forces weaken that hold solid together
- at mp - particles will have anough energy to break free from positions
- when liquid heated - particles gain more energy
- energy causes partciles move faster - weakens and breaks bonds
- bp = break their bonds = gas
What happens when a gas is cooled?
- particles no longer have enough energy to overcome forces of attraction between them
- bonds form between particles
- at bp, many bonds have formed - liquid
- liquid cools - particles have less energy to move
- more bonds form as theree is not enough energy to overcome attraction between particles
- at mp = solid,bonds held n place - freezing
cons of using particle theory for states of matter
- particles arent solid or inelastic
- not spheres
- doesnt show forces between particles - wdk the strength
Factors that affect how strong the forces that affect the state?
- material
- temp
- pressure
cons of using a dot and cross diagram
- dodnt show struccture of compound
- size ofions
- how theyre arranged
What does the discovery of isotopes tell about Mendeleev?
He was right not to place elements in a strict order of atomic weight but also take into account their properties - isotopes have dif masses but same chemical properties
