C1 - Atomic Structure Flashcards
Define atom
The smallest part of an element that can still be recognised as that element
Define element
A substance made of only one type of atom
Define compound
A substance made of two or more different atoms chemically bonded together
Define molecule
A substance made of more than one atom chemically bonded together (can be atoms of the same type!)
State the masses of the subatomic particles
Protons: 1, neutrons: 1, electrons: almost 0
State the relative charges of the subatomic particles
Protons = +1 neutrons = 0 electrons = -1
What is the plum pudding model of the atom?
A ball of positive charge with negative electrons studded into it
What did Rutherford’s alpha scattering experiment prove?
Atoms have a small dense nucleus with a positive charge.
How did Bohr adapt the model of the atom?
He said electrons orbit the nucleus at specific distances
What did Chadwick’s work give evidence of?
That the nucleus also contained neutrons as well as protons
What is the atomic number of an atom?
The number of protons in an atom
How were elements arranged in the early attempts of the periodic table?
By atomic weight
How are elements in the periodic table arranged?
By atomic number
What do you know about elements in the same group?
They have similar properties (reactions) as they have the same number of electrons in the outer shell
What are periods in the periodic table?
The rows in the periodic table
What are groups in the periodic table?
The columns, numbered 1, 2, 3, 4, 5, 6, 7, 0/8
Why did Mendeleev swap the order of some elements?
So they were in the same group as elements they had similar chemical properties with.
What is crystallisation?
When a solution is heated until crystals start to form then left to cool until all the water evaporates
What does distillation do?
Separates mixture of liquids with different boiling points
What is an isotope?
An atom with the same number of protons but a different number of neutrons.
What type of ions do metals form?
Positive ions as they lose electrons to get a full outer shell cation
What type of ions do non-metals form?
Negative ions as they gain electrons to get a full outer shell
What is group 1 called?
Alkali metals
What is group 7 called?
Halogens
What is group 0 called?
The noble gases
State the trend in the melting points of the alkali metals
Gets lower down the group
Explain why the group 1 elements are called alkali metals
They are metals that form alkalis when they react with water
What is a displacement reaction?
A reaction in which a more reactive element takes the place of a less reactive element in a compound
Why does the following reaction does not proceed: KBr + I₂
Iodine is less reactive than bromine so cannot displace it
What are the properties of the transition metals? 5 points
- they are good conductors of heat and electricity.
- they are malleable
- they have high melting points (but mercury is a liquid at room temperature)
- they are usually hard and tough.
- they have high densities.
What is an ion?
Atoms with a charge.
What is a cation?
Metal atom which has lost an electron to therefore, have a positive charge.
What is an elements atomic mass?
Number of protons + number of neutrons
What is an elements atomic number?
Number of protons
Who discovered the plum pudding model?
J.J. Thomson
Explain the alpha-particle scattering experiment.
They fired positively charged atoms at a thin piece of gold foil. Most atoms passed straight through, proving plum pudding model to be wrong. Some repelled, proving the nucleus had a positive charge.
Why did Mendeleev leave gaps in his periodic table?
To leave spaces for the elements that had not been discovered yet.
Why was Mendeleev’s table widely accepted?
Mendeleev had predicted the properties of missing elements by leaving gaps.
When these elements were discovered they matched his predictions.
What would happen if the plum pudding model was proved to be correct in the alpha particle scattering experiment?
The positively charged helium nucleus would travel straight through the atom with no reflection as charge would be spread evenly.
What happened in the alpha scattering particle experiment that led to a change in the model of the atom?
Particles deflected off the foil at an angle which showed the positive charge was concentrated in the middle of the atom.
Most particles passed straight through proving the atom to be mostly empty space.
What did J.J. Thomson discover?
The existence of electrons - led to the plum pudding model.
What was the order of the people who made discoveries of the atom?
John Dalton
J.J. Thomson
Ernest Rutherford
Neils Bohr
James Chadwick
What did John Dalton say about the atom?
Atoms were indivisible.
Atoms of the same element were the same.
And compounds are combinations of different types of atoms.
Do compounds have the same properties as their constitute elements?
No.
Do mixtures have the same properties as their constitute elements?
Yes.
What is simple distillation?
Used to separate a solvent from a solution.
Solute’s boiling points is a lot higher than the solvent it’s dissolved in.
What is the purpose of the fractionating distillation column?
Containing glass beads, helps to separate out the compounds. As it is cold at the top and hot at the bottom, the liquids will condense at different heights of the column.
What is chromatography used for?
To separate a mixture of substances dissolved in a solvent.
What is a solvent?
Substance that dissolves the solute.
What is a solute?
Gets dissolved by the solvent.
What is the radius of an atom?
0.1nm
Compare the boiling points of metals and non-metals.
Metals - high
Non-metals - low
Compare the appearance of metals and non-metals.
Metals - shiny
Non-metals - dull
Compare the conductivity of metals and non-metals.
Metals - Conduct heat and electricity
Non-metals - don’t conduct (exception of graphite)
Compare the malleability of metals and non-metals.
Metals - malleable
Non-metals - brittle
Compare the densities of non-metals and metals.
Metals - high density
Non-metals - low density
Define miscible/immiscible.
Able to be mixed / unable to be mixed.
What do the elements in the same period have in common?
Number of energy levels.
What is the trend in the properties of the noble gases down the group?
Higher boiling points down the group as atoms get heavier.
What are the properties of noble gases?
Unreactive (full outer shell), low boiling points, gases.
Compare Group 1 metals with transition metals.
Both - shiny when polished, conductors, form ionic compounds with non-metals.
Transition metals - less reactive, harder, higher densities.
Why would ordering elements in atomic weight be incorrect?
Isotopes not considered.
What 4 substances can react with an acid to form a soluble salt?
Metal oxide
Metal hydroxide
Metal carbonate
Alkali
What is the dish called in the formation of copper sulfate cystals?
Evaporating basin
Why is chlorine more reactive than iodine?
Chlorine’s outer shell electron is closer to the nucleus.
Chlorine has greater attraction for outer shell electrons.
So will gain an electron more easily.
Why do the boiling points of the halogens decrease down the group?
Size of molecules increases.
Increases strength of intermolecular force.
More energy is needed to overcome these forces.
