atomic structure and periodic table Flashcards
What are all substances made up of ?
atoms
What is an atoms radius ?
1 x 10⁻¹⁰ m
Where is a nucleus located ?
in the middle of the atom
What subatomic particles does the nucleus contain ?
protons and neutrons
What is the radius of a nucleus ?
1 x 10⁻¹⁴ m
What charge does a nucleus produce and why ?
+ve, because of the protons
Where is the majority of the mass in an atom located ?
in the nucleus
Give the three subatomic particles.
1) electron
2) proton
3) neutron
What is the relative mass of each subatomic particle ?
proton = 1
neutron = 1
electron = very small
what is the relative charge of each subatomic particle ?
proton = +1
electron = -1
neutron = 0
Where are electrons located in an atom ?
in orbit around the nucleus in shells.
The volume of an electrons orbit determines the ______ of an atom.
size
Are atoms neutral or charged ?
neutral
Why are atoms neutral ?
This is because they have the same number of electrons and protons so they cancel each other out.
Define what an ion is.
a charged particle
What does the nuclear symbol of an atom tell you ?
the atomic number and the mass number
What does the atomic number tell you ?
proton number and electron number
what does the mass number show you ?
the total number of protons and neutrons in an atom.
How do you find the number of neutrons in an atom ?
mass number - atomic number
define what the an element is.
a substance made up of atoms that all have the same number of protons in their nucleus.
What subatomic particle in an atom decides what type of atom it is ?
protons in the nucleus
Define what an isotope is.
different forms of the same element, which have the same number of protons but a different number of neutrons.
Isotopes have the same atomic number but different _____ numbers
mass
compare Carbon-12 with carbon-13 in terms of subatomic particles.
carbon-12
protons = 6
electrons = 6
neutrons = 6
carbon-13
protons = 6
electrons = 6
neutrons = 7
define what relative atomic mass is.
an average mass taking into account the different masses and abundances of all the isotopes that make up an element.
How do you work out relative atomic mass ?
(equation)
sum of abundances of all the isotopes
define what a compound is.
a substance formed from two or more different elements chemically bonded in a fixed ratio.
What subatomic particle is involved in making bonds ?
electrons - the nuclei of an atom is not affected at all when a bond is made.
How are the original elements of a compound separated ?
through a chemical reaction
Give one observation made during a chemical reaction to separate elements from a compound and how this can be measured.
one new substance is made.
This can be measured through an energy change such as a temperature change.
Give one observation made during a chemical reaction to separate elements from a compound and how this can be measured.
one new substance is made.
This can be measured through an energy change such as a temperature change.
The properties of a compound are usually totally different from the properties of the original ______________ elements.
formula for carbon dioxide
CO₂
formula for ammonia
NH₃
formula for water
H₂O
formula for sodium chloride
NaCl
formula for carbon monoxide
CO
formula for Hydrochloric acid
HCl
Calcium chloride
CaCl₂
formula for sodium carbonate
Na₂CO₃
Formula for sulfuric acid
H₂SO₄
define what a mixture is.
two or more different elements or compounds bonded together.
name 5 different types of physical methods that mixtures can be separated by ?
1) filtration
2) crystallisation
3) simple distillation
4) fractional distillation
5) chromatography
true or false, air is a mixture.
true
What is air a mixture of ?
gases :
nitrogen, oxygen, carbon dioxide and argon
What is crude oil a mixture of ?
different length hydrocarbon molecules.
How do compounds and mixtures differ in terms of properties of the original substances ?
The properties of a compound are usually totally different from the properties of the original elements whereas the properties of a mixture are just a mixture of the properties of the separate parts.
Why do the chemical properties of a mixture remain unchanged ?
Because the different parts of the mixture are not chemically combined unlike compounds.
The different parts of mixture aren’t chemically ______________, this means their chemical properties remain _____________ and the compounds or elements can be _______________ by physical methods.
bonded, unchanged, separated
What does chromatography separate ?
different dyes in an ink
Why is the line near the bottom of the sheet of filter paper drawn in pencil during chromatography ?
This is because pencil marks are insoluble and wont dissolve in the solvent.
Why do we make sure the ink isn’t touching the solvent in chromatography ?
so it doesn’t dissolve into it.
Why do we place a lid on top of the container during chromatography ?
to stop the solvent evaporating
How do you know if a dye in the ink is insoluble during chromatography ?
it’ll stay on the baseline
What is a chromatogram ?
the end result of performing chromatography which is a pattern of spots.
Describe the steps as to how you perform chromatography.
1) Draw a line near the bottom of a sheet of filter paper in pencil.
2) add a spot of ink to the line and place the sheet in a beaker of solvent.
3) make sure the ink isn’t touching the solvent.
4) place a lid on top of the container to stop the solvent evaporating.
5) The solvent seeps up the paper, carrying the ink with it.
6) each different dye in the ink will move up the paper at a different rate so the dyes will separate out and form spots.
7) when the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it to dry.
The properties of a compound are usually totally different from the properties of the original ______________ elements.
What does filtration do ?
separates insoluble solids from liquids
what does insoluble mean ?
when the solid cannot be dissolved in a liquid.
Why is filter paper used in filtration ?
so the insoluble solid is left in the filter paper.
What are two techniques to separate soluble solids from solutions ?
1) evaporation
2) crystallisation
What is meant by ‘soluble’ ?
if a solid can be dissolved
Explain how you would carry out evaporation to separate a soluble solid from a solution.
1) pour the solution into an evaporating dish
2) slowly heat the solution.
3) The solvent will evaporate and the solution will get more concentrated, leading to crystals forming.
4) Keep heating the evaporating dish until all there is left is dry crystals.
Evaporation can only be used if the salt doesn’t ______________ when its heated.
decompose
Explain how you would carry out crystallisation to separate a soluble solid from a solution.
1) Pour the solution into an evaporating dish and gently heat the solution.
2) some of the solvent will evaporate and the solution will get more concentrated.
3) when some of the solvent has evaporated or when you see crystals start to form, remove the dish from the heat and leave to cool.
4) The salt should start to from crystals as it becomes insoluble in the cold, highly concentrated solution.
5) Filter the crystals out of the solution, and leave them in a warm place to dry.
What is the ‘point of crystallisation’
when crystals start to form.
What is rock salt ?
A mixture of salt and sand.
Salt and sand are both compounds but salt ___________ in water and sand doesn’t.
dissolves
Explain how filtration and crystallisation can be used to separate rock salt. ( can also be used to separate other mixtures) .
1) Grind the mixture to make sure the salt crystals are small, so will dissolve easily.
2) Put the mixture in water and stir. The salt will dissolve, but the sand won’t.
3) filter the mixture. The grains of sand won’t fit through the tiny holes in the filter paper, so they collect on the paper instead.
4) the salt passes through the filter paper as its part of the solution.
5) evaporate the water from the salt so that it forms dry crystals of slat.
What is distillation used for ?
used to separate mixtures which contain liquids.
What is simple distillation sued for ?
separating out a liquid from a solution.
Explain how simple distillation is carried out.
1) The solution is heated.
2) The part of the solution that has the lowest boiling point evaporates first.
3) The vapour is then cooled, condenses and is collected.
4) The rest of the solution is left behind in the flask.
What does the piece of equipment the ‘condenser’ do in simple distillation ?
the vapour turns back into a liquids here as it is cooled by the water.
Identify two problems with simple distillation.
1) you can only use it to separate things with very different boiling points - if the temperature goes higher than the bpt of the substance with the higher bpt, they will mix again. #
2) if you have a mixture of liquids with similar bpt’s you need another method to separate them, like fractional distillation.
Explain the process on how you carry out fractional distillation.
1) Put the mixture in a flask and stick a fractionating column on top.
2) Heat up the flask.
3) the different liquids in the mixture will have different bpt’s so they will evaporate at different temperatures.
4) the liquid with the lowest bpt evaporates first.
5) when the temperature on the thermometer matches the bpt of this liquid, it will reach top of the column.
6) liquids with higher bpt’s might also start to evaporate
7) However the column is cooler at the top of the column so they will only get part of the way up before condensing and running back down towards the bottom of the flask.
8) When the first liquid has been collected, raise the temperature until the next on reaches the top.
What did Dalton contribute to the theory of the atomic structure in the 19th century ?
He described atoms as ______ spheres and said that different spheres made up different ____________.
solid, elements
What did JJ Thompson contribute to the theory of the atomic structure in 1897 ?
He concluded that atoms weren’t _____ spheres, his measurements of charge and mass showed that an atom must contain even smaller, _________ charged particles - electrons.
This lead him to create the _____ pudding model showing an atom as a ball of ________ charge with electrons ___________ in it.
solid, negatively, plum, positive, embedded
What did JJ Thompson contribute to the theory of the atom in 1897 ?
He concluded that atoms weren’t solid spheres, his measurements of charge and mass showed that an atom must contain even smaller, negatively charged particles -electrons.
This lead him to create the plum pudding model showing an atom as a ball of posotive charge with electrons embedded in it.
Summarise Rutherford’s discovery on the theory of the atomic structure in 1909.
He conducted the ____________ leaf experiment. He and his student fired positively charged _____ particles at a thin sheet of _____.
However instead of passing straight through which the plum pudding model would suggest, some were ___________ off the thin sheet of gold, so the plum pudding model couldn’t be _________.
Rutherford then created the ________ model of the atom comprising of a tiny _________ charged nucleus at the centre where most of the mass was concentrated with a ______ of negative electrons surrounding it.
golden, alpha, gold, deflected, accurate, nuclear, positively, cloud
Why was Rutherford expecting the particles to pass straight through the sheet during the golden leaf experiment ?
This was because the positive charge of each atom was thought to be very spread out through the plum pudding model.
What did Bohr contribute to the theory of the atomic structure ?
He discovered that electrons in a ‘cloud’ around the nucleus of an atom would be ________________ to the nucleus causing the atom to _________.
Therefore his nuclear model of the atom
suggested that all electrons were contained in _______.
He proposed that electrons orbit the nucleus in _______ shells and aren’t anywhere in between.
each shell is a fixed ___________ from the nucleus.
attracted, collapse, shells, fixed, distances
What did further experiments by Rutherford and others lead to ?
Gave the conclusion that the nucleus could be divided into smaller __________, each of which has the same ________ as a hydrogen nucleus.
charge
What did James Chadwick contribute to the development of the atomic structure ?
He carried out an experiment which provided evidence for neutral particles in the _________. These became known as __________. This discovery resulted in the model of the atom which is very similar to the nuclear model of todays world.
nucleus, neutrons
Which scientist discovered electrons ?
JJ Thompson
Which scientist discovered protons ?
Rutherford
Which scientist discovered neutrons ?
James Chadwick
Give the number of electrons that can fit in each shell in an atom.
1st shell : 2
2nd shell : 8
3rd shell : 8
Give the 5 electron shell rules.
1) electrons always occupy shells
2) The lowest energy levels are always filled first
3) only a certain number of electrons are allowed in each shell.
4) atoms are much happier when they have a full outer shell.
5) in most atoms, the outer shell is not full and this makes the atom want to react to fill it.
Give the basic steps on how to work out an elements electronic structure.
1) look at the elements atomic number on the periodic table.
2) the atomic number tells you the number of protons an element has so it also tells you the number of electrons since no. of protons = no. of electrons in an atom.
3) work out how many electrons can fit in each shell.
How was the old periodic table arranged ?
in order of atmic weight
Why was the old periodic table arranged in in order of atomic weight and not atomic number ?
Because scientists had no idea of atomic __________ or of protons, __________ or electrons so there was no such thing as the atomic ___________ until discovery’s of atomic structure came about in the 20th century.
structure, neutrons, number
Give two problems with early periodic tables.
1) they were not complete
2) the elements were placed in order of atomic weight and did not take into account their properties.
How did Mendeleev order his periodic table ?
He put the elements in order of atomic weight but did switch that order if the properties mean it should be changed.
Give two reasons why Mendeleev left gaps in his periodic table ?
1) To make sure that elements with similar properties stayed in the same groups.
2) Some of these gaps indicated the existence of undiscovered elements and allowed Mendeleev to predict what their properties might be.
The discovery of ___________ in the early 20th century confirmed that Mendeleev was correct to not place elements in a strict order of atomic ________ but to also take account of their properties.
isotopes, weight
How are elements laid out in the periodic table ?
in order of increasing atomic (proton) number.
Arranging the elements in order of increasing atomic number means there are repeating patterns in the _______________ of the elements.
properties
Which side are metals on in the periodic table ?
left
Which side are the non-metals on in the periodic table ?
right
Elements with similar properties form ____________
columns
The vertical columns in the periodic table that hold elements with similar ____________ are called _______.
properties, groups
The group number on the periodic table tells you how many ____________ there are in the outer _______.
electrons, shell
The rows in the periodic table are called ___________.
periods
each new period in the periodic table represents another full shell of _____________.
electrons.
