Topic 1 Atomic Structure And The Periodic Table Flashcards
What is the radius of an atom?
0.1 nanometers
What is the relative mass of a proton?
1
What is the relative mass of a neutron?
1
What is the relative mass of an electron?
0
What is the relative charge of a proton?
+1
What is the relative charge of a neutron?
0
What is the relative charge of an electron?
-1
What is the mass number?
The total number of protons + neutrons
What is the atomic number?
The number of protons and electrons.
What is an isotope?
Different forms of the same element which have the same number of protons but different numbers of neutrons.
What is the relative atomic mass (same as the mass number)?
An average mass taking into account the different masses and abundances of all the isotopes that make up an element.
What is a mixture?
Two substances that are mixed but not chemically joined.
What are the are the properties of a mixture like?
Just a mixture of the properties of the desperate parts.
How can mixtures be separated?
Without a chemical reaction.
What does chromatography do?
It separates substances in a solution.
When does chromatography work?
When substances are aqueous in the same solvent.
What is chromatogram?
The picture made by chromatography. Hey
What is filtration?
A method which separates insoluble from soluble substances.
What is crystallisation?
A method used to obtain s soluble substance from a solution.
What is simple distillation?
A method used to separate out a liquid from a solution.
What did John Dalton describe atoms at the start of the 19th century?
Solid spheres and that different spheres made up different elements.
What did JJ Thompson conclude from his experiments in 1879?
That atoms aren’t solid spheres.
What did JJ Thompson’s measurements of charge and mass show?
An atom must contain even smaller negatively charged particles- electrons.
What did the plum pudding model show?
The atom as a ball of positive charge with electrons stuck in it.
Which famous experiments did Rutherford and his student Marsden conduct in 1909?
The alpha particle scattering experiments.
How did Rutherford and Marsden carry out the alpha particle scattering experiments?
The fired positive ply charged alpha particles at an extremely thin sheet of gold foil.
What did Rutherford and Marsden expect the alpha particles to do?
To pass straight through the sheet or to be slightly deflected at most.
Why did Rutherford and Marsden have the expectations that they had?
Because the positive charge of the atom was thought to be very spread out through the pudding of the atom.
What actually happened to the alpha particles?
Whilst most of the particles did go through the gold sheet, some were deflected more than expected, and a small number were deflected backwards.
What idea did Rutherford come up with to explain his findings?
- The Nuclear model of the atom.
- There is a positively nucleus at the centre where the mass is concentrated and surrounded by a ‘cloud’ of electrons.
How are Rutherford’s backed up by what he saw in his experiments?
When alpha particles came near to the concentrated mass of the nucleus , they were deflected.
If fired directly at the nucleus, they were deflected backwards.
Otherwise the passed through the empty space.
How did other scientists reason that there couldn’t be a ‘cloud ‘ of electrons?
Because the electrons in a ‘cloud’ would be attracted to the nucleus causing the atom to collapse.
What did Neil Bohr’s nuclear model of the atom suggest and what did he propose?
That all the electrons were contained in ‘shells’.
That electrons orbit the nucleus in fixed shells and aren’t anywhere in between.
How were elements arranged in the early 1800s?
By atomic mass.
What were the two obvious ways to categorise elements in the early 1800s?
- Their physical and chemical properties.
- Their relative atomic mass.
How did Mendeleev arrange the periodic table?
Mainly in order of atomic mass but did switch that order if the properties meant that it should be changed.
What happened with Tellurium and Iodine in terms of organisation on the periodic table?
iodine has a smaller relative atomic mass but is placed after tellurium as it has similar properties to the elements in that group.
Why did Mendeleev leave gaps in his periodic table?
To make sure that elements, to be discovered in the future, with similar properties stayed in the same groups.
What did some of the gaps that Mendeleev left in the periodic table indicate?
The existence of undiscovered elements.
What sort of ions do metals from?
Positive ions.
What sort of ions do non-metals form?
Negative ions.
Why do metals form positive ions and non-metals form negative ions?
For metals to form positive ions it requires less energy to lose 1 than to gain lots.
For non-metals it requires less energy for them to gain 1 electron than to gain lots.
What are the general properties of metals?
4
- Strong
- Malleable
- Heat and electricity conductors
- High boiling and melting points
What are the general properties of non-metals?
5
- Dull looking
- Brittle
- Not always solid
- Don’t conduct electricity
- Lower density
What are the properties of transition metals?
11
- Shiny
- Malleable
- sonorous
- Water proof
- Conduct electricity
- Coloured Compounds
- Ductile (can be drawn into wires)
- High melting points
- Conduct heat
- Often make good catalysts
- insoluble
Why can transition metals have different numbers of ions?
Because they have different numbers of electrons on their outer shells.
Why are transition metal compounds coloured?
The electrons are able to move around and emit different colours.
What are the properties of the Alkali Metals (group 1 elements)?
(8)
- Shiny
- Low melting points
- Soft
- Low density
- Form white compounds
- Good conductors of heat and electricity
- Insoluble
- Malleable
What happens as you go down group 1?
3
- Reactivity increases
- Lower melting and boiling points
- High relative atomic mass
What are alkali metals like compared to transition metals?
Group 1 are much more reactive, less dense, less strong, less hard and have lower melting points.
What are group 7 known as?
The halogens
What are the halogens?
Non-metals with coloured vapours.
What is fluorine like?
It is very reactive and a yellow, poisonous gas.
What is chlorine like?
It is fairly reactive and a poisonous, dense, green gas.
What is bromine like?
It is a dense, poisonous, brown, volatile liquid.
What is iodine like?
It is a dark, grey, crystalline solid or a purple vapour.
What do all group 7 elements exist as?
Molecules
What happens as you go down group 7?
The halogens become:
- Less reactive (its harder to gain an extra electron because the shell is further away from the nucleus).
- Have higher melting and boiling points.
- Have higher relative atomic masses.
What will more reactive halogens do to less reactive halogens?
Displace them.
Why are all the Nobel gases inert (they don’t react much)?
They all have 8 electrons in their outer shell, making them stable.
Helium has two.
What sort of gases are noble gases?
Monatomic gases- single atoms are not bonded to each other.
Describe al the noble gases.
They are all colourless, non-flammable gases at room temperature.
What happened as you go down the noble gases?
- The boiling points and relative atomic masses increase.
- The increase in boiling point is due to an increase in the number of electrons meaning there are greater intermolecular forces.
