C1: Atomic Structure Flashcards
What is an element?
A substance with same-type atoms
What is a compound and what are their properties?
2 or more different elements that are chemically combined in fixed proportion.
They have different chemical properties to the elements they’re made of.
The elements can be separated again using chemical separation techniques.
What is a mixture?
Different elements or compounds that are not chemically combined.
They are separated using physical separation techniques.
What is a molecule?
Any elements which are chemically combined, even if they’re the same type.
What are the physical separation techniques?
Filtration
Crystallisation
Distillation
Chromatography
What is filtration?
The process of separating an insoluble solid from a liquid
Describe the process of filtration
Pour mixture into filter paper, which is over a filter funnel. The liquid passes through the funnel and into a beaker underneath the funnel, whereas the solid material sticks to the filter paper.
What is crystallisation?
The process of separating a soluble solid from a liquid
Describe the process of crystallisation
Place mixture in an evaporating basin and hold over a Bunsen burner, until most of the water evaporates. It will leave a little water and some salt. Leave on a towel to dry and form crystals
What is simple distillation?
Used to separate a liquid from a solid by taking advantage of differing boiling points. Also used if you want to keep the liquid
What is fractional distillation?
Used to separate a liquid from a liquid by taking advantage of differing boiling points
Describe the setup of simple distillation
Place solution into a round bottom flask, which is connected to a continuous glass tube, which is surrounded by a jacked (condenser). Cold water/ ice is into the condenser, which cools down the liquid. The tube goes into another beaker. A thermometer is also included.
Describe the process of simple distillation
Heat the solution. The liquid will start to evaporate, rise up the glass tube and the thermometer will show a temp rise. The vapour passes through the condenser, and turns back into a liquid and is collected into a beaker.
What is the plum-pudding model?
A ball of positive charge with negative electrons embedded in it. (Early model of the atom)
What is the alpha-scattering experiment?
Scientists took a piece of gold foil (can be hammered into a few atoms thick). They fired tiny alpha particles (Positively charged). They noticed that some of them just passed through without changing direction. Sometimes it was deflected, and other times it completely bounced off.
What did the alpha-scattering experiment conclude?
Atoms are mainly empty space.
The centre of the atom had a positive charge.
The mass of the atom is concentrated in the centre.
What is the nuclear model?
Where most of the atom is mostly empty space, with a positive nucleus and a cloud of electrons.
What did Bohr propose?
The electrons orbit the nucleus at specific distances (as a cloud of electrons would cause the atom to collapse) and it agreed with the results of experiments of other scientists.
What did Chadwick propose?
Nucleus also contains neutrons
What is the radius of the atom?
0.1nm (1*10^-10m)
Approximation, some atoms larger than others
What is the radius of the nucleus?
1*10^14m
What are the masses of subatomic particles?
Proton - +1, 1
Neutron - 0 1
Electron - -1 1/1000 (very small?)
What is an isotope?
Atoms of an element with different numbers of neutrons.
What is an ion?
Atoms with have an overall charge - they have gained or lost electrons.
What is the atomic mass of an element?
The total number of protons and neutrons of an atom
What is the atomic number of an element?
Number of protons in an atom of the element
What is the relative atomic mass of an element?
The average of the mass numbers of the different isotopes, weighted for the abundance of each isotope.
