Topic 1 - Atomic Structure Flashcards
All substances are made from?
Atoms.
Substances made from only one type of atom are called?
Elements.
The periodic table is arranged in?
Groups of elements with shared properties.
Give an example of a group in the periodic table.
Group 1, the Alkali Metals.
What is the name given to structures containing more than one element bonded together?
A compound.
Finish the sentence about atomic structure - Every atom is made up of a _______ and _________ orbiting it in ________.
Nucleus, Electrons, Shells.
What do we mean by a “balanced” equation?
An equation with an equal amount of each element on each side.
Balance the equation for water. This equation is imbalanced -> H2 + O2 ————> H2O
2H2 + O2 ——> 2H2O
Give the law of conservation of mass.
The mass of products formed in a reaction is equal to mass of reactants.
What is a difference between a compound and a mixture?
Compounds have a fixed composition of elements that are bonded together whereas mixtures have no fixed composition and can be made up of many elements at once.
List four ways of separating compounds in a mixture.
Crystallisation, Filtration, Distillation, Chromatography.
What does filtration do?
Separates compounds that are soluble in the solvent from ones which are insoluble in the solvent. For example separating water from sand using filtration paper.
What does Crystallisation do?
Separates elements that can be evaporated from one’s that cannot by evaporation and allow the solid element to cool and crystallise, forming pure crystals of the element.
What is the difference between distillation and crystallisation?
Crystallisation doesn’t collect the evaporative element whereas distillation cools and condenses the evaporative element into a liquid again to be collected, making the new liquid pure.
Why is paper chromatography useful for separating elements?
Some elements will dissolve better than others in the solvent, the solubility of the element being determined by how far up the chromatogram the elements go.
Who were the first peoples to have ideas about the atom?
The Greeks.
What did the Greeks think about the atom?
That it was a small, undivided ball of metal.
What was Dalton’s breakthrough about the structure of the atom?
Each atom were hard, tiny spheres and that each chemical element had their own type of atom.
Who discovered the electron?
J.J Thompson
How did J.J Thompson discover this?
By applying high voltages to gases at high temperatures.
What did J.J Thompson find out about electrons?
That they were negatively charged and were smaller than atoms and made up atoms, discovering that there were smaller things than the atom.
What was J.J Thompson’s new Plum Pudding model like?
He proposed that electrons floated in a sea of positive charged randomly like plums in a pudding
Who made the breakthrough about alpha particles and the nucleus?
Geiger and Marsden.
What did Geiger and Marsden discover about the nucleus?
That it had to be a highly dense concentration of positive charge as, in their gold foil experiment, most positively charged particles went straight through the atom, but ones which hit the nucleus fired straight back, this happened very rarely and they determined most of the atom was empty space.
What was proposed after Geiger and Marsden’s breakthrough?
That the nucleus contained positively charged protons and that negatively charged electrons orbited around the nucleus in shells.
What did James Chadwick add to the atomic model?
James Chadwick observed a discrepancy between predicted and real mass of the nucleus and determined that neutrally charge neutrons were present in the nucleus alongside the protons.
What sub-atomic particles are contained in the nucleus?
Protons and Neutrons.
What sub-atomic particle type orbits around the nucleus?
Electrons.
What is the relative mass and charge of a proton?
Protons have a relative mass of 1 and a relative charge of +1.
What is the relative mass and charge of a neutron?
A neutron has a relative mass of 1 and a relative charge of 0.
What is the relative mass and charge of an electron?
An electron has a relative mass of 1/2000 (nearly 0) and a relative charge of -1.
What is the name given to the number of protons in an element?
Atomic Number.
What is the name given to the total mass of protons and neutrons in an element?
Mass Number.
What is an ion?
An atom which has lost or gained electrons compared with its original form. In other words, it is a charged atom.
Atoms of the same element but different numbers of neutrons are called?
Isotopes.
Electrons orbit the nucleus in?
Shells or energy levels.
How many electrons fit inside the first shell?
2
How many electrons fit inside the second and third shells?
8
What is the arrangement of electrons in Oxygen? (Atomic number 8)
2,6
What is the arrangement of electrons in Aluminium? (Atomic number 13)
2,8,3
What is the arrangement of electrons in Calcium? Atomic number 20)
2,8,8,2
Elements in Group 0 (8) of the periodic table are called?
Noble gases.
What is the most unreactive group of elements?
Noble gases/group 0.
When is fractional distillation used?
When separating more than two types of liquids from a homogeneous mixture. E.g. different hydrocarbons from crude oil.
What is the method for paper chromatography?
Place a sheet of paper in a beaker filled with a shallow layer of your solvent.
Ensure the level of solvent is below the pencil line.
Place a lid on the beaker and leave the solvent to travel up the paper, carrying the different compounds of the mixture to different levels of the chromatogram.
How do you calculate Rf value?
Divide the distance travelled by the component by the distance travelled by the solvent.
- This is part of paper 2 but still useful.
Why can we be sure that there are no missing elements in the first 10 elements?
We have named, identified and characterised all of the 10 elements and since protons cannot be split, there cannot be unknown elements within the periodic table.
Why do group 1 elements increase in reactivity as we go down the periodic table?
Because, since they have greater atomic numbers, their outer shells are further away from the nucleus and since they lose electrons in group 1, they have less of a strong bond with the nucleus and thus it can lose its outer electron more quickly.
Why do group 7 elements decrease in reactivity as we go down the periodic table?
Group 7 elements gain electrons, since their outer shells are closer to the nucleus if they have a lower atomic number and are thus higher up the perioidic table, they can attract an electron more easily if they have a low atomic number. Thus they are more reactive.
