C1 - Atomic Structure and the Periodic table Flashcards
Atoms, Elements, Compounds, Mixtures, Chromatography, Separation Techniques, Distillation, History of the atom, Electronic structure, Development of the periodic table, Modern Periodic table, metals, non metals, group 1, group 7, group 0.
Atoms -
What do atoms contain?
Protons and neutrons
Atoms -
What is the radius of an atom?
0.1 nanometres
Atoms -
What is the nucleus?
- middle of atom
- contains protons and neutrons
- radius of 1 x 10 power -14
-positive charge - almost whole mass concentrated in nucleus
Atoms -
What are electrons + what do they do?
- in electron shells/ energy levels
- negatively charged
- volume of their obits determine size of atom
- no mass (virtually)
Atoms -
What is number of protons equal to?
Number of electrons
Atoms-
What is the charge of an atom and why?
- neutral charge
- same number protons and electrons
Atoms -
Why is there a difference in charge between an atom and an ion?
- atoms have no charge as they are neutral
- ions have a charge because the number of protons and electrons are different.
Atoms -
What does the nuclear model of the atom tell you?
- atomic (proton) number
- mass number
Atoms -
What does the atomic number tell you?
- number of protons
Atoms -
What does the mass number tell you?
- total number of protons and neutrons
Atoms -
How do you calculate number of neutrons?
mass number - atomic number = neutrons
Atoms -
What is an ion?
An atom or group of atoms that has lost or gained electrons
Elements -
What is an element?
A substance made up of atoms that all have the same number of protons in their nucleus.
Elements -
What decides the type of atom something is?
Number of protons in the nucleus
Elements -
How many different elements are there?
About 100
Elements -
What makes elements different?
The number of protons in their nucleus
Elements -
What are isotopes?
Forms of the same elements with same number of protons but different number of neutrons. (same atomic mass but different mass number)
Elements -
What are popular examples of a pair of isotopes?
- carbon-12
- carbon-13
Elements -
What is the equation to calculate relative atomic mass (Ar) of an element?
sum of (isotope abundance x isotope mass number) / sum of abundance of all isotopes
Elements -
Why is Ar used instead of mass number when referring to the element as a whole?
Because many elements exist as a number of different isotopes
Compounds -
How are compounds formed?
When elements react, atoms combine with other atoms to form compounds
Compounds -
What is a compound?
Substances formed from two or more elements, atoms of each are in fixed proportions and held together by chemical bonds.
Compounds -
What does making bonds in a compounds involve?
Atoms sharing electrons
Compounds -
What isn’t affected when a bond is made in a compound?
Nuclei of atoms.
Compounds -
What is needed to separate original elements in a compound?
Chemical reaction
Compounds -
What happens when a mental and non metal react to form a compound?
- Compound formed that consists of ions.
- metal - lose electrons so have + charge
- non metal - gain electrons so have - charge
Compounds -
What do opposite charges of ions in a compound mean?
That they are strongly attracted to each other (ionic bonding).
Compounds -
What is involved in ionic bonding?
Metals and non metals
Compounds -
What is involved in covalent bonding?
Non metals
Compounds -
What happens during covalent bonding?
Atoms of each non - metal share an electron with another atom.
Compounds -
Examples of covalently bonded compounds:
Hydrogen chloride gas, carbon monoxide, water
Compounds -
What are the properties of a compound usually totally different to?
The properties of the original elements.
Mixture -
What is difference between a compound and a mixture?
- Mixture has no chemical bonds
- parts can elements or compounds
- separated using physical methods
Mixture -
What are the physical methods used to separate parts of mixture?
- filtration
- crystallisation
- simple distillation
- fractional distillation
- chromatography
( Physical methods don’t involve a chemical reaction so don’t form any new substances)
Mixture -
Which gases is the air a mixture of?
- mainly nitrogen
- oxygen
- carbon dioxide
- argon
Mixture -
What is crude oil a mixture of?
Different length hydrocarbon molecules
Mixture -
What are the properties of a mixture?
-Mixture of the properties of the separate parts.
(chemical properties of a substance aren’t affected by it being part of mixture)
Paper Chromatography -
What is a chromatography one example of?
Separating substances in a mixture
Paper Chromatography -
What can chromatography be used to separate?
Dyes in an ink
Paper Chromatography - Required Practical
Method of paper chromatography:
- Draw line using pencil near bottom of filter paper. (because pencil marks are insoluble and won’t dissolve in solvent)
- Add spot of ink to line and place sheet in a beak of solvent (eg water)
- Solvent used depends on what’s being tested. (some compounds dissolve well in water, sometime ethanol needed)
- Ink not touching solvent (don’t want it to dissolve into solvent)
- Place lid on top of container to stop solvent evaporating.
- Solvent seeps up paper carrying the ink.
- Different dye in the ink move up paper at different rate so dyes separate out. (each dye form spot in different place - one spot per dye in ink)
- If any dye in ink insoluble they stay at baseline.
- When solvent nearly reach top of paper (solvent front) take paper out and leave to dry.
- End result is a pattern of spots called a chromatogram.
Separation Techniques -
What does filtration do?
Separates insoluble solids from liquids.
Separation Techniques -
When can filtration be used?
If your product is an insoluble solid that needs to be separated from a liquid reaction mixture.
Separation Techniques -
What can filtration also be used in?
Purification (solid impurities in reaction mixture separated)
Separation Techniques -
What shape is filter paper folded into during filtration?
Cone shape placed in a funnel over a beaker.
Separation Techniques -
What are the 2 ways to separate soluble solids from solution?
- Evaporation
- Crystallisation
Separation Techniques -
What is an example of soluble solid?
Soluble salt
Separation Techniques - Required Practical
Method of evaporation:
- Pour solution in evaporating dish
- Slowly heat (solvent evaporate and solution get more concentrated) to eventually form crystals
- Keep heating evaporating dish until ;left with dry crystals
Separation Techniques -
When can evaporation be used?
- if the salt doesn’t decompose when heated
Separation Techniques -
Why is crystallisation used instead of evaporation?
If the salt decomposes when heated
Separation Techniques - Required practical
Method of crystallisation:
(used to make big crystals of salt)
- Pour solution into evaporating dish + gently heat solution. (some solvent evaporated and solution become more concentrated)
- When you see crystals start to form (point of crystallisation) remove from heat and leave solution to cool.
- Salt start to form crystals as becomes insoluble on cold, highly concentrated solutions
4.Filter crystals out, leave in warm place to dry. (use drying oven or desiccator)
Separation Techniques -
What can filtration and crystallisation be used to separate?
Rock salt
Separation Techniques -
What is rock salt?
Mixture of salt and sand (spread in roads in winter)
Separation Techniques -
What are salt and sand both?
Compounds
Separation Techniques -
What can salt do by sand can’t?
Salt can dissolve in water
(difference in physical properties mean they be separated using filtration and crystallisation)
Separation Techniques - Required Practical
How to separate rock salt?
- Grind mixture so salt small - dissolve easily
- Put mixture in water + stir. (salt dissolve, sand won’t) - can heat to help dissolve salt
- Filter mixture. Sand won’t fit through filter paper so collect. Salt pass through filter paper as part of solution.
- Evaporate water from salt so forms dry crystals. (could crystallisation if wanted big crystals)
Distillation - Required Practical
What are the two types of distillation?
- Simple
- Fractional
Distillation - Required Practical
What is simple distillation used for?
Separating out a liquid from a solution
Distillation - Required Practical
Method of simple distillation:
- Solution heated (part of solution with lowest boiling point evaporate first)
- Vapour cooled, condenses (the vapour turns back into a liquid as it is cooled by the water going into the condenser) and collected
- Rest of solution left in beaker.
Distillation - Required Practical
What is an example of a solution that you can use simple distillation to get pure water from and how?
- Seawater
(Water evaporates, condensed, collected. Eventually left with just salt in the flask).
Distillation - Required Practical
What is the problem with simple distillation?
- only separate things with very different boiling points (if temp goes higher than boiling point of substance with higher boiling point they mix again).
Distillation - Required Practical
What is fractional distillation used for?
Separating a mixture of liquids
Distillation - Required Practical
Fractional distillation method:
- Put mixture in flask and put a fractionating column on top + heat
- Different liquids have different boiling points - evaporate at different temperatures
- Liquid with lowest boiling point evaporate first ( when temp matches boiling point of liquid it reach the top of the column)
- Liquids with higher boiling points also start to evaporate but column cooler at top so won’t get all the way up before condensing and running back down towards the flask
- When first liquid collected, raise temperature until next one reaches top.
Distillation - Required Practical
What is an example of when fractional distillation is used?
To separate crude oil into fractions at a refinery
The History of the Atom -
How has the theory of the atomic structures changed?
- John Dalton - atoms solid spheres and different spheres made up different elements
- J J Thomson - atoms not solid spheres but contain electrons. Change theory to plum pudding model
- Plum pudding model showed that atom was ball of positive charge with electrons stuck in.
The History of the Atom -
How did Rutherford show that the plum pudding model was wrong?
- Rutherford and Marsden (his student) conducted alpha particle scattering experiments. (fired positively charged alpha particles at thin sheet of gold)
- Expecting particles to pass straight through or be slightly deflected - positive charge of each atom was though to be spread out through the atom.
- However, most particles went straight through, some deflected more than expected, small number deflected backwards. Proved plum pudding model wrong.
The History of the Atom -
What was Rutherford’s new idea?
- Nuclear model of the atom.
- contains positively charged nucleus at centre (most mass concentrated), cloud of electrons surround nucleus - most of atom empty space.
- alpha particles near nucleus - deflected
- alpha particles directly at nucleus - deflected backwards
- alpha particles otherwise pass through empty space
The History of the Atom -
What did scientists realise about the electrons in Rutherford’s model?
Would be attracted to nucleus causing atom to collapse.
The History of the Atom -
What did Bohr’s nuclear model suggest?
- Electrons contained in shells
- Electrons orbit nucleus in fixed shells at fixed distances from the nucleus
The History of the Atom -
What did scientists discover from further experiments that showed nucleus can be divided into smaller particles?
Protons
The History of the Atom -
What was disovered about 20 years after scientists accepted that atoms have a nuclei by James Chadwick?
Neutral particles in nucleus called neutrons
The History of the Atom -
What did the discovery of neutrons result in?
The model of the atom being close to the modern day version called the nuclear model
The History of the Atom -
What is the order of the discovery of particles in an atom?
- Electrons
- Protons
- Neutrons
Electronic Structure -
What are the electron shell rules?
- Electrons always occupy shells
- Lowest shell always filled first (closet to the nucleus)
- 1st shell = 2 , 2nd shell = 8, 3rd shell = 8
- Atoms less reactive when they have full electron shells (noble gases)
- Most atoms outer shell not full mean atoms react to fill it
Development of the Periodic Table -
How were elements arranged in the early 1800?
By atomic weight (what we now called relative atomic mass)
Development of the Periodic Table -
What were the two ways until recently to categories elements?
- Physical + chemical properties
- atomic weight (what we no call relative atomic mass)
Development of the Periodic Table -
Arrangement of elements in the early 1800s:
- Scientists didn’t know structure or protons, neutrons, electrons so no atomic number
- Measured atomic weight so known elements arranged in order of atomic weight. (when done, periodic pattern of properties of elements noticed)
- Early periodic table not complete + some elements in wrong group as placed in atomic weight order and properties not considered.
Development of the Periodic Table -
How are elements arranged in the modern day periodic table?
atomic number
Development of the Periodic Table -
What did Mendeleev do?
- left gaps
- predicted new elements
- arranged mainly in order of atomic weight but switched elements not being similar to other in that group eg Tellurium and Iodine.
Development of the Periodic Table -
Why did Mendeleev leave gaps in his periodic table?
- Make sure elements with similar properties stayed in the same groups.
Development of the Periodic Table -
What did some of the gaps in the periodic indicate and allow Mendeleev to do
- the existence of undiscovered elements
- allowed him to predict what their properties might be (when found and fitted pattern helped confirm Mendeleev’s ideas)
Development of the Periodic Table -
What did the discovery of isotopes confirm?
-Mendeleev correct not to place elements in strict order of atomic weight but also think of their properties.
Development of the Periodic Table -
What do isotopes of element have?
-different masses
- same chemical properties (occupy same position on periodic table)
Modern Periodic Table -
How many elements are there?
100
Modern Periodic Table -
How are the elements in the modern periodic table laid out?
Increasing atomic (proton) number - means their are repeating patterns in properties of elements.
Modern Periodic Table -
Where are metals and non metals located on the modern periodic table?
- Metals: left
- Non metals: right
Modern Periodic Table -
What do elements with similar properties form?
Groups
Modern Periodic Table -
What does the group number tell you?
How many electrons are in the outer shell
Modern Periodic Table -
What are the rows called and what do they represent?
- Periods
- Each new period represents another full shell of electrons
Metals and Non - Metals -
What are metals?
Elements which form positive ions when they react
Metals and Non - Metals -
What do atoms generally react to form?
Full outer shell (via losing, gaining or sharing electrons)
Metals and Non - Metals -
What do metals that don’t have many electrons to remove and metals that have outer shells far away from the nucleus mean that they feel?
Weaker attraction - not a lot of energy to remove electrons to easy to form positive ions with a full outer shell
Metals and Non - Metals -
How do non metals get a full outer shell?
Share or gain electrons to form negative ions.
Metals and Non - Metals -
What do all metals have?
Metallic bonding
Metals and Non - Metals -
What are the basic physical properties of metals?
- strong
- malleable
- great conductors of heat and electricity
- high melting and boiling points
Metals and Non - Metals -
What are the basic physical properties of non metals?
- dull looking
- brittle
- not always solids at room temp
- don’t usually conduct electricity
- lower density
Metals and Non - Metals -
What are the properties of transition metal?
- good conductors
- dense
- strong
- shiny
Special properties:
- can have more than one ion (Cu + and Cu 2+)
- coloured
- transition metal compounds are good catalysts
Group 1 Elements -
What are the group 1 elements known as?
Alkali metals
Group 1 Elements -
What are alkali metals?
Reactive + soft metals with low densities
Group 1 Elements -
How many electrons do alkali metals have on their outer shell?
One electron so they are very reactive
Group 1 Elements -
What are the trends in the alkali metals as you go down the group?
- increase reactivity: electron easily lost as attraction between nucleus and electron decreases as further away the further down the group.
- lower melting/ boiling point
- higher relative atomic mass
Group 1 Elements -
What do alkali metals form when they react with non metals?
Ionic compounds (generally white solids that dissolve in water to form colourless solutions).
Group 1 Elements -
What happens when an alkali metal reacts with water?
- vigorously
- produce hydrogen gas
- produce metal hydroxides (compounds dissolve in water produce alkaline solutions)
Group 1 Elements -
What happens when an alkali metal reacts with chlorine?
- vigorously when heated with chlorine gas - form metal chloride salts
Group 1 Elements -
What happens when an alkali metal reacts with oxygen?
- form metal oxide
- lithium reacts with oxygen to form lithium oxide
- sodium reacts to form sodium oxide and sodium peroxide
- potassium reacts to form potassium peroxide and potassium superoxide
Group 1 Elements -
What are the differences in the properties of the alkali metals and the transition metal?
- alkali metals more reactive (react more vigorously with water, oxygen and group 7 elements)
- alkali metals less dense, strong, hard
- alkali metals much lower melting points
Group 7 Elements -
What are the halogens?
non metals with coloured vapours
Group 7 Elements -
What are the coloured vapours that the halogens form and the colours?
- fluorine: yellow gas
- chlorine: dense green gas
- bromine: dense red-brown volatile liquid
- iodine: dark grey solid, purple vapour
Group 7 Elements -
What do the halogens exist as?
Diatomic molecules
Group 7 Elements -
What happens if you go down group 7?
- less reactive - harder to gain electron as outer shells further away from nucleus
- higher melting and boiling points
- higher relative atomic masses
Group 7 Elements -
What do halogens form when they share electrons with other non metals?
Covalent bonds to achieve a full outer shell
(compounds formed are simple molecular structures).
Group 7 Elements -
What bonds do halogens form when they react with metals?
ionic bonds
Group 7 Elements -
What are formed when halogens react with metals?
halides
(have ionic structures)
Group 7 Elements -
What happens if there is a more reactive halogen in a reaction?
It will displace the less reactive halogen through a displacement reaction
Group 0 Elements -
How many electrons are on the outer shell of the noble gases?
eight (apart from helium which has 2) meaning have a full outer shell (stable + unreactive)
Group 0 Elements -
What do the noble gases exist as?
Monatomic gases (single atoms not bonded to each other)
Group 0 Elements -
What are the properties and patterns in the noble gases?
- boiling points increases down group (due to greater intermolecular forces that need to overcome)
