Atomic structure Flashcards
what are the subatomic particles and their charges?
protons (+), neutrons (/), electrons (-)
what are the relative masses of subatomic particles?
protons- 1, neutrons 1, electrons 1/2000 (very small)
where are the subatomic particles found?
protons and neutrons in nucleus and electrons in shells which orbit
what’s an ion?
when charges in an atom aren’t balanced, different number of protons and electrons
what’s atomic mass? what’s atomic number?
- No. of protons+ neutrons
- No. of protons
How do we know two elements are the same?
if they have the same number of protons
what’s an isotope?
the different forms of an element, where the no. of protons is the same but diff no. of neutrons
how do we calculate the relative atomic mass?
sum of (isotope mass x isotope abundance) / sum of abundances
what’s a molecule?
what’s a compound?
A group of 2 or more SAME atoms, chemically bonded
A group of 2 or more DIFFERENT atoms, chemically bonded
Define mixture.
Two or more substances NOT chemically combined but together in the same space.
Describe filtration.
Uses filter paper to separate insoluable solids and liquids.
Describe evaporation + crystallization.
Separates solutions. Heat (water bath) causes solvent to evaporate, remaining solution gets more concentrated and crystals start to form.
How can mixtures be separated?
Filtration,
crystallization, simple distillation, fractional distillation and
chromatography
What is thermal decomposition?
When a substance breaks down due to heat.
Describe simple distillation.
Separates out a liquid from a solution. Heat up solution, liquid with lower BP evaporates then condenses (water jacket).
Who founded the plum pudding model?
J.J Thompson
Describe the plum pudding model
Suggested that the atom is a ball of positive charge with negative electrons embedded in it
Who found the existence of neutrons.
James Chadwick
Who conducted the gold foil experiment?
Rutherford
Go through the gold foil experiment.
Fired alpha particles (much denser) at gold foil. Some rebounded, some passed through, some deflected. (Nuclear model)= + charged nucleus, electrons orbit.
What did the results of the gold foil experiment conclude?
Some deflected, rebounded, and passed through. Nucleus in centre, mostly empty space.
Who found out about the existence of electron shells.
Niels Bohr.
Go through the history of the atom.
Solid spheres- John Dalton
Plum pudding- J.J. Thompson
Nuclear model- Rutherford
(Adp) Nuclear model- Bohr
(Adp+) (Shells)- Chadwick
In what order was each subatomic particle found?
Electron, proton and neutron
Why do atoms react?
To get an outer shell (gain/lose electrons) to be unreactive
What is meant by an ‘unstable’ atom?
It wants to react with another atom to have a full outer shell
In what order is the modern periodic table arranged?
Increasing atomic number —>
What’s relative atomic mass?
An average value that
considers the abundance of the isotopes of the element
Why is the periodic table arranged the way it is?
Increasing atomic number, so that elements with similar properties are in
columns, known as groups.
What do the groups show in the periodic table?
Number of electrons in outer shells (similar properties)
How were the early period tables arranged? Why was this not appropriate?
In order of atomic weights, some elements were
placed in inappropriate groups if the strict order of atomic weights
was followed.
What did Mendeleev do to overcome the problems in the early periodic table?
He left gaps in the periodic table for elements he thought has not been discovered.
When metals react, what type of ion do they form?
Positive ions.
When non-metals react, what do they form?
Negative ions.
Why do metals form positive ions when they react?
They have fewer electrons in their outer shell, so they lose electrons
Why do non-metals form negative ions?
They have more electron in the out shell, so they need to gain electrons
Why do metals get more reactive as you go down the table?
The atoms gets bigger so there are more shells. Electrons further away from nucleus so less force of attraction.
What some of the differences between metals and non-metals.
Metals- Malleable, strong, conductors, shiny + sonorous
Non-metals- Brittle, Dull, low MP/BP, poor conductors
Define atom.
The smallest part of any element that can exist
What’s an element?
A substance with the same type of atoms
Describe the order of the development of the atomic structure.
John Dalton: Matter can’t be created or destroyed.
J.J. Thompson: Plum pudding model
Rutherford: Rutherford model
Bohr: Bohr model
Nuclear model
Why do atoms not collapse?
Nuclear attraction, the protons in the nucleus are attracted to the electrons orbiting.
What are the features of the group 0 elements?
BP/MP rises as you go down, unreactive (full outer shells)
Explain the features of the alkali metals.
Reactivity increases as you down the group, low density, soft, low BP/MP, reactive with water (forms metal hydroxide + hydrogen)
Explain what happens when the alkali metals react with water.
Lithium- fizzes, red flame
Sodium- fizzes more, orange flame
Potassium- fizzes most, lilac flame
They all form metal hydroxide + hydrogen
Explain the features of the group 7 elements.
Reactivity goes down as you go down, MP/BP rises
Why does reactivity go down for group 7 elements as you go down the group?
They need to gain an electron to have a full outer shell. As you go down, the atom gets bigger and there are more shells, so it becomes more difficult to gain an electron due to weaker force of attraction.
